Something I've always been curious about, many companies that advertise "Size specific chainstays" only grow the chainstay like, 2mm between sizes. Are they just moving the...
Something I've always been curious about, many companies that advertise "Size specific chainstays" only grow the chainstay like, 2mm between sizes. Are they just moving the pivot locations to increase the chainstay length? Because that would make such small increments make sense rather than a whole new rear triangle thats 2mm larger lol
It really depends on the linkage that they use, and how they try to preserve the kinematics. A lot of the time that is how it is done, since it reduces the number of parts that they need to make. You already need to make 4 different front triangles for an S-XL size run, why make 4 different size rear triangles or 4 different size chainstays and seatstays? Keeps inventory organization easier, fewer skus etc and is just practical. You can also keep the kinematics more or less the same between sizes, since all the moving parts of the linkage will be in the same place relative to each other.
Another thing about this is that, generally speaking, if you lengthen your RC by making the chainstay longer without moving pivot locations, you increase your starting and over all leverage ratio. Since the people generally asking for longer RCs are taller (and therefore generally heavier) that might not be the best thing. A higher starting leverage means higher spring rates or shock pressures, which isn't always the best. For heavier riders, I would try to have a lower starting leverage, too keep the shock pressures lower and put less force through the shock, where lighter riders can have higher leverages to overcome friction easier. Size specific kinematics are expensive and take a lot of work, and you won't be able to account for all riders since weight can vary so much between people on the same size frame. There's a lot of personal preference and design philosophy in here, I'm not a big fan of high leverage bikes since it makes tuning the shock just a bit more annoying in my experience, especially at the end of the rebound.
Why make 4 separate rear ends? To have the bikes ride properly.
Why even make 4 different front ends if inventory drives the story.
And kinematics are very much dependant on centre of gravity or the height of it. To have the same antisquat performance (or antirise), a taller rider NEEDS different kinematics than a smaller rider.
My bike (Nicolai G1) geo:HA: ~62.5ºSA: ~78ºR: 510mmWB: 1349mmCS: 474mmFC:RC 1.85Handlebar height: 113cm (used to run 107cm for years)I've run this same bike with 442mm, 453mm...
My bike (Nicolai G1) geo:
HA: ~62.5º SA: ~78º R: 510mm WB: 1349mm CS: 474mm FC:RC 1.85 Handlebar height: 113cm (used to run 107cm for years)
I've run this same bike with 442mm, 453mm and 462mm chainstays. My current setup offers the most front end grip and is the easier to corner. I would love to try 500mm chainstays and see how the bike would handle with FC:RC 1.75. I have found that the longer the chainstays the more stack you can run and still have loads of front end grip. Long chainstays also allow me to climb steep stuff without the front lifting and without needing to shift your weight forward.
So I think longer sizes need longer chainstays and 450mm isn't enough. Also BB heights should be higher in general especially as bikes have gotten longer. Also seat tube angles should be steeper on the larger sizes and not the other way around.
The Be More Bikes guy aparantly is making an enduro bike with a 520mm reach and 503-533 chainstays, built around his weird stem. Might want to...
The Be More Bikes guy aparantly is making an enduro bike with a 520mm reach and 503-533 chainstays, built around his weird stem. Might want to hit him up to see if he needs test riders.
I have talked to him a few times online. Unfortunately, I live in the French Alps so it's a bit far to get a test ride on his prototypes. They are very interesting though. Enjoyed Brian Cahal's test ride on the DH version last year.
How are we calculating F/R ratio? I assume it's (WB-CS)/CS = F/R ratio?
If that's the case- I may have accidentally ended up with 2 bikes with the exact same F/R ratio (S4 stumpy Evo and an old S2 Status). Could be an interesting comparison... Have only been jumping the status, but might need to set it up for some trail riding too.
How are we calculating F/R ratio? I assume it's (WB-CS)/CS = F/R ratio? If that's the case- I may have accidentally ended up with 2 bikes with...
How are we calculating F/R ratio? I assume it's (WB-CS)/CS = F/R ratio?
If that's the case- I may have accidentally ended up with 2 bikes with the exact same F/R ratio (S4 stumpy Evo and an old S2 Status). Could be an interesting comparison... Have only been jumping the status, but might need to set it up for some trail riding too.
How are we calculating F/R ratio? I assume it's (WB-CS)/CS = F/R ratio? If that's the case- I may have accidentally ended up with 2 bikes with...
How are we calculating F/R ratio? I assume it's (WB-CS)/CS = F/R ratio?
If that's the case- I may have accidentally ended up with 2 bikes with the exact same F/R ratio (S4 stumpy Evo and an old S2 Status). Could be an interesting comparison... Have only been jumping the status, but might need to set it up for some trail riding too.
It's not the whole story when it comes to handling, but it does determine where the reach and stack should be to compliment the f/r ratio, and ultimately determine riding position.
Personally, in size larges, I've found that 1.8 is the happy number, up to 1.84. Past that cornering performance starts to suffer unless you're riding that front end like a unicycle (longer reach, lower stack).
Above 1.85 you're driving the bike with your hands and shoulders as much as your feet. Below that and you are progressively driving the bike with your feet and hips more.
How are we calculating F/R ratio? I assume it's (WB-CS)/CS = F/R ratio? If that's the case- I may have accidentally ended up with 2 bikes with...
How are we calculating F/R ratio? I assume it's (WB-CS)/CS = F/R ratio?
If that's the case- I may have accidentally ended up with 2 bikes with the exact same F/R ratio (S4 stumpy Evo and an old S2 Status). Could be an interesting comparison... Have only been jumping the status, but might need to set it up for some trail riding too.
My s4 stumpy is pretty short in terms of reach but with the addition of the longer CS I have a nice balance on the trail. Just having the same ratio between two bikes won’t translate to their riding the same. Reach and stack is a huge piece of what makes a bike ride well for a person of a given size.
Another big missing piece in our conversation ls here here is CoG which depends on the rider’s height and build. I think bigger riders experience bigger swings in CoG than smaller riders. They have a larger mass up top and so longer reach bikes, especially with lower stacks, will shift their CoG even farther forward. I think this does two things: one, it makes designers assume that there will be more weight on the front, and for some riders this is true. Two, it makes smaller riders not understand the plight of the large/extra large frame riders. Smaller riders are already on a balanced bike and don’t understand what it’s like having a bike that throws your CoG around as much as the long and low bikes do for say a 6 foot tall rider.
for your S2 status, you’re going to have a lot of mass getting thrown out the front of the bike when you’re in big compressions and heavy braking (edit: and less leverage to help brace yourself with your arms…) Yeah the ratio will be the same but your body mass will be interacting with it very differently. But please try it out and tell me what your experience is!!!
Mostly want to test short bike vs long bike. When I do the testing- will try to normalize tires and swap the fork/front wheel between bikes to keep everything as similar as possible.
not trying to be the guy to beat a dead drum about something nobody cares about, but here I am - my take is that rad and rad angle are more important than front rear ratio. If you control the rad and rad angle between bikes, the difference in the ratio becomes much less pronounced. (Still preferential but I do find lower ratios better for higher speed sweeping turns, and higher ratios better for squaring off corners). Someone else alluded to it earlier or elsewhere, but bikes approaching a 1.9 ratio typically need longer stems and higher rise bars compared to their lower ratio, lower stack counterparts.
My recent lay experiments have been between a madonna and enduro... controlling the rad helps with the CoG stuff previously mentioned.
not trying to be the guy to beat a dead drum about something nobody cares about, but here I am - my take is that rad...
not trying to be the guy to beat a dead drum about something nobody cares about, but here I am - my take is that rad and rad angle are more important than front rear ratio. If you control the rad and rad angle between bikes, the difference in the ratio becomes much less pronounced. (Still preferential but I do find lower ratios better for higher speed sweeping turns, and higher ratios better for squaring off corners). Someone else alluded to it earlier or elsewhere, but bikes approaching a 1.9 ratio typically need longer stems and higher rise bars compared to their lower ratio, lower stack counterparts.
My recent lay experiments have been between a madonna and enduro... controlling the rad helps with the CoG stuff previously mentioned.
I’d argue that these are doing opposite things to achieve a similar end result. How a bike fits you in the sense of RAD or RAD angle is absolutely important, but I don’t think we can say that these numbers in isolation can replace looking at FC/RC balance. They are two different metrics that each have influence on one another.
What you’re referring to is adjusting the riders COG to suit the wheelbase balance of the bike, where as achieving a certain FC/RC balance is adjusting the wheelbase/balance to suit the riders COG in there preferred riding position.
I think the reason this is important to distinguish between is that dynamically these 2 setups will be different. While a riders COG might be balanced between the wheels, the rider themselves also has a balance point (weight distribution between hands and feet). This is where riders have been feeling the benefits of longer chainstays, and shorter reaches/higher stacks, as it aligns closer to their natural balance point while keeping the weight distribution balanced between the wheels. Using the BB as the “fulcrum” point for the riders balance point is fairly reasonable, because this is where your feel are located and you’re essentially rotating around that point with your body.
Riders with shorter legs and longer torsos tend to keep their weight more centered over the bb as they squat down. Riders with longer legs and shorter torso tend to push their hips further backwards as they squat down. The shorter legged rider has an easier time shifting their weight forward ahead of the BB, as their hips are already closer to this fulcrum. Whereas the longer legged rider has to throw some shapes and really shift their hips forward to get the same result. IMO, this is why we see such a polarizing opinion chainstay length. You have to establish where the rider feels most comfortable on the bike fit wise (ie reach, stack, RAD, etc), and the adjust where the front and rear wheels sit in relation to their body proportions and preferences.
not trying to be the guy to beat a dead drum about something nobody cares about, but here I am - my take is that rad...
not trying to be the guy to beat a dead drum about something nobody cares about, but here I am - my take is that rad and rad angle are more important than front rear ratio. If you control the rad and rad angle between bikes, the difference in the ratio becomes much less pronounced. (Still preferential but I do find lower ratios better for higher speed sweeping turns, and higher ratios better for squaring off corners). Someone else alluded to it earlier or elsewhere, but bikes approaching a 1.9 ratio typically need longer stems and higher rise bars compared to their lower ratio, lower stack counterparts.
My recent lay experiments have been between a madonna and enduro... controlling the rad helps with the CoG stuff previously mentioned.
I’d argue that these are doing opposite things to achieve a similar end result. How a bike fits you in the sense of RAD or RAD...
I’d argue that these are doing opposite things to achieve a similar end result. How a bike fits you in the sense of RAD or RAD angle is absolutely important, but I don’t think we can say that these numbers in isolation can replace looking at FC/RC balance. They are two different metrics that each have influence on one another.
What you’re referring to is adjusting the riders COG to suit the wheelbase balance of the bike, where as achieving a certain FC/RC balance is adjusting the wheelbase/balance to suit the riders COG in there preferred riding position.
I think the reason this is important to distinguish between is that dynamically these 2 setups will be different. While a riders COG might be balanced between the wheels, the rider themselves also has a balance point (weight distribution between hands and feet). This is where riders have been feeling the benefits of longer chainstays, and shorter reaches/higher stacks, as it aligns closer to their natural balance point while keeping the weight distribution balanced between the wheels. Using the BB as the “fulcrum” point for the riders balance point is fairly reasonable, because this is where your feel are located and you’re essentially rotating around that point with your body.
Riders with shorter legs and longer torsos tend to keep their weight more centered over the bb as they squat down. Riders with longer legs and shorter torso tend to push their hips further backwards as they squat down. The shorter legged rider has an easier time shifting their weight forward ahead of the BB, as their hips are already closer to this fulcrum. Whereas the longer legged rider has to throw some shapes and really shift their hips forward to get the same result. IMO, this is why we see such a polarizing opinion chainstay length. You have to establish where the rider feels most comfortable on the bike fit wise (ie reach, stack, RAD, etc), and the adjust where the front and rear wheels sit in relation to their body proportions and preferences.
I appreciate the detailed response, but I disagree completely.
I’m stating that if you have the same rad and rad angle, the ratio stuff becomes preference. In other words, I think that once a rider knows their preferred rad, they rip on either side of the 1.85 ratio spectrum and feel comfortable doing so.
not trying to be the guy to beat a dead drum about something nobody cares about, but here I am - my take is that rad...
not trying to be the guy to beat a dead drum about something nobody cares about, but here I am - my take is that rad and rad angle are more important than front rear ratio. If you control the rad and rad angle between bikes, the difference in the ratio becomes much less pronounced. (Still preferential but I do find lower ratios better for higher speed sweeping turns, and higher ratios better for squaring off corners). Someone else alluded to it earlier or elsewhere, but bikes approaching a 1.9 ratio typically need longer stems and higher rise bars compared to their lower ratio, lower stack counterparts.
My recent lay experiments have been between a madonna and enduro... controlling the rad helps with the CoG stuff previously mentioned.
I’d argue that these are doing opposite things to achieve a similar end result. How a bike fits you in the sense of RAD or RAD...
I’d argue that these are doing opposite things to achieve a similar end result. How a bike fits you in the sense of RAD or RAD angle is absolutely important, but I don’t think we can say that these numbers in isolation can replace looking at FC/RC balance. They are two different metrics that each have influence on one another.
What you’re referring to is adjusting the riders COG to suit the wheelbase balance of the bike, where as achieving a certain FC/RC balance is adjusting the wheelbase/balance to suit the riders COG in there preferred riding position.
I think the reason this is important to distinguish between is that dynamically these 2 setups will be different. While a riders COG might be balanced between the wheels, the rider themselves also has a balance point (weight distribution between hands and feet). This is where riders have been feeling the benefits of longer chainstays, and shorter reaches/higher stacks, as it aligns closer to their natural balance point while keeping the weight distribution balanced between the wheels. Using the BB as the “fulcrum” point for the riders balance point is fairly reasonable, because this is where your feel are located and you’re essentially rotating around that point with your body.
Riders with shorter legs and longer torsos tend to keep their weight more centered over the bb as they squat down. Riders with longer legs and shorter torso tend to push their hips further backwards as they squat down. The shorter legged rider has an easier time shifting their weight forward ahead of the BB, as their hips are already closer to this fulcrum. Whereas the longer legged rider has to throw some shapes and really shift their hips forward to get the same result. IMO, this is why we see such a polarizing opinion chainstay length. You have to establish where the rider feels most comfortable on the bike fit wise (ie reach, stack, RAD, etc), and the adjust where the front and rear wheels sit in relation to their body proportions and preferences.
I appreciate the detailed response, but I disagree completely. I’m stating that if you have the same rad and rad angle, the ratio stuff becomes preference. In...
I appreciate the detailed response, but I disagree completely.
I’m stating that if you have the same rad and rad angle, the ratio stuff becomes preference. In other words, I think that once a rider knows their preferred rad, they rip on either side of the 1.85 ratio spectrum and feel comfortable doing so.
Sure they might be maintaining the same standing body position on any bike that they've set up to have the same rad and rad angle measurements, and they're equally comfortable standing on either bike, but that does not translate to the bike having the same handling characteristics. You can't disregard the physical geometry of a bike by using Rad, you'll likely walk away with some bad results doing so. Like kapolczer implied, Rad doesn't account for a riders proportions, and that affects where your center of gravity is while riding. Whether or not you follow the Rad system is a matter of personal preference, and it's a very useful tool, but it's not the end all be all.
not trying to be the guy to beat a dead drum about something nobody cares about, but here I am - my take is that rad...
not trying to be the guy to beat a dead drum about something nobody cares about, but here I am - my take is that rad and rad angle are more important than front rear ratio. If you control the rad and rad angle between bikes, the difference in the ratio becomes much less pronounced. (Still preferential but I do find lower ratios better for higher speed sweeping turns, and higher ratios better for squaring off corners). Someone else alluded to it earlier or elsewhere, but bikes approaching a 1.9 ratio typically need longer stems and higher rise bars compared to their lower ratio, lower stack counterparts.
My recent lay experiments have been between a madonna and enduro... controlling the rad helps with the CoG stuff previously mentioned.
I’d argue that these are doing opposite things to achieve a similar end result. How a bike fits you in the sense of RAD or RAD...
I’d argue that these are doing opposite things to achieve a similar end result. How a bike fits you in the sense of RAD or RAD angle is absolutely important, but I don’t think we can say that these numbers in isolation can replace looking at FC/RC balance. They are two different metrics that each have influence on one another.
What you’re referring to is adjusting the riders COG to suit the wheelbase balance of the bike, where as achieving a certain FC/RC balance is adjusting the wheelbase/balance to suit the riders COG in there preferred riding position.
I think the reason this is important to distinguish between is that dynamically these 2 setups will be different. While a riders COG might be balanced between the wheels, the rider themselves also has a balance point (weight distribution between hands and feet). This is where riders have been feeling the benefits of longer chainstays, and shorter reaches/higher stacks, as it aligns closer to their natural balance point while keeping the weight distribution balanced between the wheels. Using the BB as the “fulcrum” point for the riders balance point is fairly reasonable, because this is where your feel are located and you’re essentially rotating around that point with your body.
Riders with shorter legs and longer torsos tend to keep their weight more centered over the bb as they squat down. Riders with longer legs and shorter torso tend to push their hips further backwards as they squat down. The shorter legged rider has an easier time shifting their weight forward ahead of the BB, as their hips are already closer to this fulcrum. Whereas the longer legged rider has to throw some shapes and really shift their hips forward to get the same result. IMO, this is why we see such a polarizing opinion chainstay length. You have to establish where the rider feels most comfortable on the bike fit wise (ie reach, stack, RAD, etc), and the adjust where the front and rear wheels sit in relation to their body proportions and preferences.
I appreciate the detailed response, but I disagree completely. I’m stating that if you have the same rad and rad angle, the ratio stuff becomes preference. In...
I appreciate the detailed response, but I disagree completely.
I’m stating that if you have the same rad and rad angle, the ratio stuff becomes preference. In other words, I think that once a rider knows their preferred rad, they rip on either side of the 1.85 ratio spectrum and feel comfortable doing so.
RAD is ergonomics. Can also effect the weight distribution but ultimately we are looking at how weight applied to the pedals is distributed to the front and rear tires. I am disinterested in systems that require me to weight the bars. The RAD “solution” you’ve outlined does not solve for riding through the feet.
I think what you mean is that where a rider weights the bike to get front wheel traction is a matter of preference. I agree with that.
I’d argue that these are doing opposite things to achieve a similar end result. How a bike fits you in the sense of RAD or RAD...
I’d argue that these are doing opposite things to achieve a similar end result. How a bike fits you in the sense of RAD or RAD angle is absolutely important, but I don’t think we can say that these numbers in isolation can replace looking at FC/RC balance. They are two different metrics that each have influence on one another.
What you’re referring to is adjusting the riders COG to suit the wheelbase balance of the bike, where as achieving a certain FC/RC balance is adjusting the wheelbase/balance to suit the riders COG in there preferred riding position.
I think the reason this is important to distinguish between is that dynamically these 2 setups will be different. While a riders COG might be balanced between the wheels, the rider themselves also has a balance point (weight distribution between hands and feet). This is where riders have been feeling the benefits of longer chainstays, and shorter reaches/higher stacks, as it aligns closer to their natural balance point while keeping the weight distribution balanced between the wheels. Using the BB as the “fulcrum” point for the riders balance point is fairly reasonable, because this is where your feel are located and you’re essentially rotating around that point with your body.
Riders with shorter legs and longer torsos tend to keep their weight more centered over the bb as they squat down. Riders with longer legs and shorter torso tend to push their hips further backwards as they squat down. The shorter legged rider has an easier time shifting their weight forward ahead of the BB, as their hips are already closer to this fulcrum. Whereas the longer legged rider has to throw some shapes and really shift their hips forward to get the same result. IMO, this is why we see such a polarizing opinion chainstay length. You have to establish where the rider feels most comfortable on the bike fit wise (ie reach, stack, RAD, etc), and the adjust where the front and rear wheels sit in relation to their body proportions and preferences.
I appreciate the detailed response, but I disagree completely. I’m stating that if you have the same rad and rad angle, the ratio stuff becomes preference. In...
I appreciate the detailed response, but I disagree completely.
I’m stating that if you have the same rad and rad angle, the ratio stuff becomes preference. In other words, I think that once a rider knows their preferred rad, they rip on either side of the 1.85 ratio spectrum and feel comfortable doing so.
RAD is ergonomics. Can also effect the weight distribution but ultimately we are looking at how weight applied to the pedals is distributed to the front...
RAD is ergonomics. Can also effect the weight distribution but ultimately we are looking at how weight applied to the pedals is distributed to the front and rear tires. I am disinterested in systems that require me to weight the bars. The RAD “solution” you’ve outlined does not solve for riding through the feet.
I think what you mean is that where a rider weights the bike to get front wheel traction is a matter of preference. I agree with that.
Im specifically referencing rad and rad angle from that calculator. I am not referring to the philosophy of fitting bikes with rad. I’m not saying that fc ratio doesn’t affect riding characteristics and not making any statements on weight distribution between the setups.
I am saying that fc ratio is confounded with other changes to bike setup and when controlling for specific bike setup (i.e. rad and rad angle), it’s easy to switch between the “long chain stay gang” and short chain stays.
Aka pick your favorite bike, toss it in the calculator then go ride another bike on the opposite end of the ratio spectrum setup to have the same rad measures. You’ll still be able to rip. Yes, they have a different feel, yes the cornering technique is different. Yes they’re suited to different riding style and terrain.
I’d argue that these are doing opposite things to achieve a similar end result. How a bike fits you in the sense of RAD or RAD...
I’d argue that these are doing opposite things to achieve a similar end result. How a bike fits you in the sense of RAD or RAD angle is absolutely important, but I don’t think we can say that these numbers in isolation can replace looking at FC/RC balance. They are two different metrics that each have influence on one another.
What you’re referring to is adjusting the riders COG to suit the wheelbase balance of the bike, where as achieving a certain FC/RC balance is adjusting the wheelbase/balance to suit the riders COG in there preferred riding position.
I think the reason this is important to distinguish between is that dynamically these 2 setups will be different. While a riders COG might be balanced between the wheels, the rider themselves also has a balance point (weight distribution between hands and feet). This is where riders have been feeling the benefits of longer chainstays, and shorter reaches/higher stacks, as it aligns closer to their natural balance point while keeping the weight distribution balanced between the wheels. Using the BB as the “fulcrum” point for the riders balance point is fairly reasonable, because this is where your feel are located and you’re essentially rotating around that point with your body.
Riders with shorter legs and longer torsos tend to keep their weight more centered over the bb as they squat down. Riders with longer legs and shorter torso tend to push their hips further backwards as they squat down. The shorter legged rider has an easier time shifting their weight forward ahead of the BB, as their hips are already closer to this fulcrum. Whereas the longer legged rider has to throw some shapes and really shift their hips forward to get the same result. IMO, this is why we see such a polarizing opinion chainstay length. You have to establish where the rider feels most comfortable on the bike fit wise (ie reach, stack, RAD, etc), and the adjust where the front and rear wheels sit in relation to their body proportions and preferences.
I appreciate the detailed response, but I disagree completely. I’m stating that if you have the same rad and rad angle, the ratio stuff becomes preference. In...
I appreciate the detailed response, but I disagree completely.
I’m stating that if you have the same rad and rad angle, the ratio stuff becomes preference. In other words, I think that once a rider knows their preferred rad, they rip on either side of the 1.85 ratio spectrum and feel comfortable doing so.
Sure they might be maintaining the same standing body position on any bike that they've set up to have the same rad and rad angle measurements...
Sure they might be maintaining the same standing body position on any bike that they've set up to have the same rad and rad angle measurements, and they're equally comfortable standing on either bike, but that does not translate to the bike having the same handling characteristics. You can't disregard the physical geometry of a bike by using Rad, you'll likely walk away with some bad results doing so. Like kapolczer implied, Rad doesn't account for a riders proportions, and that affects where your center of gravity is while riding. Whether or not you follow the Rad system is a matter of personal preference, and it's a very useful tool, but it's not the end all be all.
I agree it’s not the end all be all. My point is that neither is fc ratio. Standardizing rad across your bikes objectively removes one area of variation and lets the rider focus on different nuances from riding bikes at either end of the ratio spectrum.
Has anyone tried matching the rad measurement across bikes on opposite ends of the spectrum?
https://madscientistmtb.com/rad-calc/Im specifically referencing rad and rad angle from that calculator. I am not referring to the philosophy of fitting bikes with rad. I’m not saying...
Im specifically referencing rad and rad angle from that calculator. I am not referring to the philosophy of fitting bikes with rad. I’m not saying that fc ratio doesn’t affect riding characteristics and not making any statements on weight distribution between the setups.
I am saying that fc ratio is confounded with other changes to bike setup and when controlling for specific bike setup (i.e. rad and rad angle), it’s easy to switch between the “long chain stay gang” and short chain stays.
Aka pick your favorite bike, toss it in the calculator then go ride another bike on the opposite end of the ratio spectrum setup to have the same rad measures. You’ll still be able to rip. Yes, they have a different feel, yes the cornering technique is different. Yes they’re suited to different riding style and terrain.
“…You’ll still be able to rip. Yes, they have a different feel, yes the cornering technique is different. Yes they’re suited to different riding style and terrain.”
Brother, that’s just called being good at bikes and is kind of besides the point 😂
I have no way to test this, but I really do believe front-rear ratio will turn out to be a very important metric in bike design or, better yet, bike choice going into the future. Especially in larger sizes. It won't be one value to rule them all, as someone being ABLE to ride over the front will be able to manage a higher ratio, but someone not being able to ride over the front (someone pulling back defensively) will for sure benefit from a lower ratio by having more balanced grip over the two wheels.
Saying that a correct RAD/RAAD will make you be able to ignore the chainstay length and still rip, based on the above (rider position) I do not see how that would be possible outside of having a really short front end to couple with short chainstays to get the grip. With a given RAD and RAAD, that can only mean a helluva steep headtube angle...
Also, if RAD and RAAD is SO important, you can modify it to some extent with handlebar height, stem length, bar roll, etc. But that doesn't tell you anything where that front wheel is (or the rear obviously). As above, different front-rear ratios will require different posture to weight the two correctly. Which means two different bikes with the same RAD and RAAD will have to be ridden differently. Which by default goes against the claims that the same RAD/RAAD will make two different bikes ride the same.
I'm not saying RAD/RAAD is useless (but I do not see the benefit of calculating two arbitrary values from two different arbitrary values, reach and stack, which is what RAD and RAAD is, just trigonometry with a fancier name), I'm trying to say it needs to be looked at holistically.
EDIT: regarding the calculator linked on above page, I have a pet-peeve. There are A LOT of values for handlebar geometry listed there, but as noted in the 'help' balloon, they are hard to find from the manufacturers. Better yet, the calculator obviously suggests eyeballing some values, has a black box calculation trying to estimate hand position, complicates things with grip diameter, etc., giving a very exact RAD and RAAD value, but basing everything off of VERY murky geometry. Handlebar rise is very loosely defined (it is not the total vertical height of the bar), setback is not taken into account anywhere, it's somewhat extrapolated based of how most bars look, etc. A lot of guesstimation to give you hundreds of mm and hundreds of a degree on the end result? While you could be off by milimiters based on your bar geometry guesstimation.
I have no way to test this, but I really do believe front-rear ratio will turn out to be a very important metric in bike design...
I have no way to test this, but I really do believe front-rear ratio will turn out to be a very important metric in bike design or, better yet, bike choice going into the future. Especially in larger sizes. It won't be one value to rule them all, as someone being ABLE to ride over the front will be able to manage a higher ratio, but someone not being able to ride over the front (someone pulling back defensively) will for sure benefit from a lower ratio by having more balanced grip over the two wheels.
Saying that a correct RAD/RAAD will make you be able to ignore the chainstay length and still rip, based on the above (rider position) I do not see how that would be possible outside of having a really short front end to couple with short chainstays to get the grip. With a given RAD and RAAD, that can only mean a helluva steep headtube angle...
Also, if RAD and RAAD is SO important, you can modify it to some extent with handlebar height, stem length, bar roll, etc. But that doesn't tell you anything where that front wheel is (or the rear obviously). As above, different front-rear ratios will require different posture to weight the two correctly. Which means two different bikes with the same RAD and RAAD will have to be ridden differently. Which by default goes against the claims that the same RAD/RAAD will make two different bikes ride the same.
I'm not saying RAD/RAAD is useless (but I do not see the benefit of calculating two arbitrary values from two different arbitrary values, reach and stack, which is what RAD and RAAD is, just trigonometry with a fancier name), I'm trying to say it needs to be looked at holistically.
EDIT: regarding the calculator linked on above page, I have a pet-peeve. There are A LOT of values for handlebar geometry listed there, but as noted in the 'help' balloon, they are hard to find from the manufacturers. Better yet, the calculator obviously suggests eyeballing some values, has a black box calculation trying to estimate hand position, complicates things with grip diameter, etc., giving a very exact RAD and RAAD value, but basing everything off of VERY murky geometry. Handlebar rise is very loosely defined (it is not the total vertical height of the bar), setback is not taken into account anywhere, it's somewhat extrapolated based of how most bars look, etc. A lot of guesstimation to give you hundreds of mm and hundreds of a degree on the end result? While you could be off by milimiters based on your bar geometry guesstimation.
The technique is absolutely different, no doubt, but I’m suggesting that standardizing your rad and raad puts the rider in a position where they can perform on either side of the spectrum. I’m not suggesting to ignore chainstay length.
Still curious to hear from those who run multiple bikes across the ratio spectrum. When I tossed my bikes in the calculator, I was surprised to find they all were in a very close window from each other. That was just from my natural setup over the years, not purposely trying to match the rad values.
It wasn’t too long ago Cahal had a similar epiphany riding an ibis. FWIW I think the fc ratio is a bigger tell on what type of terrain an enduro bike is best suited for.
I appreciate the detailed response, but I disagree completely. I’m stating that if you have the same rad and rad angle, the ratio stuff becomes preference. In...
I appreciate the detailed response, but I disagree completely.
I’m stating that if you have the same rad and rad angle, the ratio stuff becomes preference. In other words, I think that once a rider knows their preferred rad, they rip on either side of the 1.85 ratio spectrum and feel comfortable doing so.
RAD is ergonomics. Can also effect the weight distribution but ultimately we are looking at how weight applied to the pedals is distributed to the front...
RAD is ergonomics. Can also effect the weight distribution but ultimately we are looking at how weight applied to the pedals is distributed to the front and rear tires. I am disinterested in systems that require me to weight the bars. The RAD “solution” you’ve outlined does not solve for riding through the feet.
I think what you mean is that where a rider weights the bike to get front wheel traction is a matter of preference. I agree with that.
https://madscientistmtb.com/rad-calc/Im specifically referencing rad and rad angle from that calculator. I am not referring to the philosophy of fitting bikes with rad. I’m not saying...
Im specifically referencing rad and rad angle from that calculator. I am not referring to the philosophy of fitting bikes with rad. I’m not saying that fc ratio doesn’t affect riding characteristics and not making any statements on weight distribution between the setups.
I am saying that fc ratio is confounded with other changes to bike setup and when controlling for specific bike setup (i.e. rad and rad angle), it’s easy to switch between the “long chain stay gang” and short chain stays.
Aka pick your favorite bike, toss it in the calculator then go ride another bike on the opposite end of the ratio spectrum setup to have the same rad measures. You’ll still be able to rip. Yes, they have a different feel, yes the cornering technique is different. Yes they’re suited to different riding style and terrain.
I wouldn’t even want the same rad on two very differently balanced bikes. Consistent rad across bikes makes zero sense as there are very different geo and body positioning needs depending on terrain and discipline. I would love the same fc/rc ratio AND rad on all my bikes, but if I could only choose one consistent variable it would be fc/rc ratio. Let the rad change depending on how I’m riding the bike.
RAD is ergonomics. Can also effect the weight distribution but ultimately we are looking at how weight applied to the pedals is distributed to the front...
RAD is ergonomics. Can also effect the weight distribution but ultimately we are looking at how weight applied to the pedals is distributed to the front and rear tires. I am disinterested in systems that require me to weight the bars. The RAD “solution” you’ve outlined does not solve for riding through the feet.
I think what you mean is that where a rider weights the bike to get front wheel traction is a matter of preference. I agree with that.
https://madscientistmtb.com/rad-calc/Im specifically referencing rad and rad angle from that calculator. I am not referring to the philosophy of fitting bikes with rad. I’m not saying...
Im specifically referencing rad and rad angle from that calculator. I am not referring to the philosophy of fitting bikes with rad. I’m not saying that fc ratio doesn’t affect riding characteristics and not making any statements on weight distribution between the setups.
I am saying that fc ratio is confounded with other changes to bike setup and when controlling for specific bike setup (i.e. rad and rad angle), it’s easy to switch between the “long chain stay gang” and short chain stays.
Aka pick your favorite bike, toss it in the calculator then go ride another bike on the opposite end of the ratio spectrum setup to have the same rad measures. You’ll still be able to rip. Yes, they have a different feel, yes the cornering technique is different. Yes they’re suited to different riding style and terrain.
I wouldn’t even want the same rad on two very differently balanced bikes. Consistent rad across bikes makes zero sense as there are very different geo...
I wouldn’t even want the same rad on two very differently balanced bikes. Consistent rad across bikes makes zero sense as there are very different geo and body positioning needs depending on terrain and discipline. I would love the same fc/rc ratio AND rad on all my bikes, but if I could only choose one consistent variable it would be fc/rc ratio. Let the rad change depending on how I’m riding the bike.
https://madscientistmtb.com/rad-calc/Im specifically referencing rad and rad angle from that calculator. I am not referring to the philosophy of fitting bikes with rad. I’m not saying...
Im specifically referencing rad and rad angle from that calculator. I am not referring to the philosophy of fitting bikes with rad. I’m not saying that fc ratio doesn’t affect riding characteristics and not making any statements on weight distribution between the setups.
I am saying that fc ratio is confounded with other changes to bike setup and when controlling for specific bike setup (i.e. rad and rad angle), it’s easy to switch between the “long chain stay gang” and short chain stays.
Aka pick your favorite bike, toss it in the calculator then go ride another bike on the opposite end of the ratio spectrum setup to have the same rad measures. You’ll still be able to rip. Yes, they have a different feel, yes the cornering technique is different. Yes they’re suited to different riding style and terrain.
I wouldn’t even want the same rad on two very differently balanced bikes. Consistent rad across bikes makes zero sense as there are very different geo...
I wouldn’t even want the same rad on two very differently balanced bikes. Consistent rad across bikes makes zero sense as there are very different geo and body positioning needs depending on terrain and discipline. I would love the same fc/rc ratio AND rad on all my bikes, but if I could only choose one consistent variable it would be fc/rc ratio. Let the rad change depending on how I’m riding the bike.
The technique is absolutely different, no doubt, but I’m suggesting that standardizing your rad and raad puts the rider in a position where they can perform...
The technique is absolutely different, no doubt, but I’m suggesting that standardizing your rad and raad puts the rider in a position where they can perform on either side of the spectrum. I’m not suggesting to ignore chainstay length.
Still curious to hear from those who run multiple bikes across the ratio spectrum. When I tossed my bikes in the calculator, I was surprised to find they all were in a very close window from each other. That was just from my natural setup over the years, not purposely trying to match the rad values.
It wasn’t too long ago Cahal had a similar epiphany riding an ibis. FWIW I think the fc ratio is a bigger tell on what type of terrain an enduro bike is best suited for.
I’ve run a single bike with a fairly large range of FC/RC ratios. Having a the ability to change the rear center +10 and +20mm means all other factors stay the same (bar, stem, spacers, etc), so having the ratio range from 1.88, 1.84 and 1.80 respectively.
All these setups rode noticeably different. And in my experience, the longer rear centre's meant a higher bar heights to achieve a similar rider balance point. All of these setups were rideable for me absolutely. But personally, the longest chainstay felt too long and I struggled to get the weight off the front wheel when I needed to, and the shortest chainstay is very active and requires a more forward riding position. I have short legs and a longer torso, so my preferences make sense to me.
So in my experience, (and without crunching the numbers in detail) I would say that a lower FC/RC ratio benefits from a larger RAD angle. The RAD length probably doesn’t change too much, but depending on the length of the RC, it would likely benefit from getting slightly shorter the longer you go. I think this is what Brian Cahal noted on the ibis he rode, that with a higher ratio, if he ran the front end lower (smaller rad angle) it was still rideable, but not his preferred position, as it’s was more aggressive over the front than he would like to be.
If you’ve found RAD to be of benefit for you when moving between bikes, that’s awesome. But I think it’s only one small piece of a larger puzzle, and the reality is that bikes have sorted out reach and stack numbers pretty well, riders have a ton of option. But it’s FC/RC that have been negatively impacted as bikes have gotten longer, and that’s what people are looking for to change on new bikes to better suit their needs.
I wish there were more reviews out there for his bikes. It would be cool to see how the known commodity reviewers experience his approach to bike geometry. What limited reviews exist seem positive, but it's really just two or three guys on MTBR.
A 495 chainstay and a 435 reach on a L/XL is wild, but the wheelbase is pretty standard. New bikes seem to be creeping up closer to his stack heights, though.
The technique is absolutely different, no doubt, but I’m suggesting that standardizing your rad and raad puts the rider in a position where they can perform...
The technique is absolutely different, no doubt, but I’m suggesting that standardizing your rad and raad puts the rider in a position where they can perform on either side of the spectrum. I’m not suggesting to ignore chainstay length.
Still curious to hear from those who run multiple bikes across the ratio spectrum. When I tossed my bikes in the calculator, I was surprised to find they all were in a very close window from each other. That was just from my natural setup over the years, not purposely trying to match the rad values.
It wasn’t too long ago Cahal had a similar epiphany riding an ibis. FWIW I think the fc ratio is a bigger tell on what type of terrain an enduro bike is best suited for.
I’ve run a single bike with a fairly large range of FC/RC ratios. Having a the ability to change the rear center +10 and +20mm means...
I’ve run a single bike with a fairly large range of FC/RC ratios. Having a the ability to change the rear center +10 and +20mm means all other factors stay the same (bar, stem, spacers, etc), so having the ratio range from 1.88, 1.84 and 1.80 respectively.
All these setups rode noticeably different. And in my experience, the longer rear centre's meant a higher bar heights to achieve a similar rider balance point. All of these setups were rideable for me absolutely. But personally, the longest chainstay felt too long and I struggled to get the weight off the front wheel when I needed to, and the shortest chainstay is very active and requires a more forward riding position. I have short legs and a longer torso, so my preferences make sense to me.
So in my experience, (and without crunching the numbers in detail) I would say that a lower FC/RC ratio benefits from a larger RAD angle. The RAD length probably doesn’t change too much, but depending on the length of the RC, it would likely benefit from getting slightly shorter the longer you go. I think this is what Brian Cahal noted on the ibis he rode, that with a higher ratio, if he ran the front end lower (smaller rad angle) it was still rideable, but not his preferred position, as it’s was more aggressive over the front than he would like to be.
If you’ve found RAD to be of benefit for you when moving between bikes, that’s awesome. But I think it’s only one small piece of a larger puzzle, and the reality is that bikes have sorted out reach and stack numbers pretty well, riders have a ton of option. But it’s FC/RC that have been negatively impacted as bikes have gotten longer, and that’s what people are looking for to change on new bikes to better suit their needs.
Appreciate the insight. I found similar results going from -5, 0, +5 chainstay settings and playing with fork travel. I think the part about Cahal and the lower front end goes against standardizing the rad angle - would be curious to hear his and others results if it stays the same as his preferred ride. I'm squarely in the middle of size large for all my bikes, so that could influence why im not hitting the 'unrideable' limit at either end of the spectrum.
I think someone mentioned 1.85 as the inflection point earlier in the thread or in another thread. This has been my experience as well, faster trails like at Windrock and Kanuga, I prefer a lower ratio, but anything in Arizona, Oklahoma, and Arkansas where you have to generate speed/shorter downhills/natural turns, the higher ratio bike is the one I reach for.
I don't agree with RAD either tbh, and with longer chainstay bikes I'll prefer a longer bb-to-bar distance as well as a much higher bar, so I really wouldn't say that once you've got your "RAD" sorted that you can get along with a wider range of geometries. I used to think RAD was a reasonable idea, but then I rode more bikes that challenged my views. I don't think I'd go full "raised reverse", to me that seems like fucking up the cockpit of a bike so badly that you need geometry that's too extreme for most trails to fix what you've fucked up.
If RAD was the answer then my drop bar XC bike would be unrideable.
It really depends on the linkage that they use, and how they try to preserve the kinematics. A lot of the time that is how it is done, since it reduces the number of parts that they need to make. You already need to make 4 different front triangles for an S-XL size run, why make 4 different size rear triangles or 4 different size chainstays and seatstays? Keeps inventory organization easier, fewer skus etc and is just practical. You can also keep the kinematics more or less the same between sizes, since all the moving parts of the linkage will be in the same place relative to each other.
Another thing about this is that, generally speaking, if you lengthen your RC by making the chainstay longer without moving pivot locations, you increase your starting and over all leverage ratio. Since the people generally asking for longer RCs are taller (and therefore generally heavier) that might not be the best thing. A higher starting leverage means higher spring rates or shock pressures, which isn't always the best. For heavier riders, I would try to have a lower starting leverage, too keep the shock pressures lower and put less force through the shock, where lighter riders can have higher leverages to overcome friction easier. Size specific kinematics are expensive and take a lot of work, and you won't be able to account for all riders since weight can vary so much between people on the same size frame. There's a lot of personal preference and design philosophy in here, I'm not a big fan of high leverage bikes since it makes tuning the shock just a bit more annoying in my experience, especially at the end of the rebound.
I can confirm that even forbidden used the method of moving the pivot locations and using one rear triangle for their first gen bikes.
Why make 4 separate rear ends? To have the bikes ride properly.
Why even make 4 different front ends if inventory drives the story.
And kinematics are very much dependant on centre of gravity or the height of it. To have the same antisquat performance (or antirise), a taller rider NEEDS different kinematics than a smaller rider.
I have talked to him a few times online. Unfortunately, I live in the French Alps so it's a bit far to get a test ride on his prototypes. They are very interesting though. Enjoyed Brian Cahal's test ride on the DH version last year.
How are we calculating F/R ratio? I assume it's (WB-CS)/CS = F/R ratio?
If that's the case- I may have accidentally ended up with 2 bikes with the exact same F/R ratio (S4 stumpy Evo and an old S2 Status). Could be an interesting comparison... Have only been jumping the status, but might need to set it up for some trail riding too.
That or FC/RC which is basically the same.
Yep. I have always done (WB-CS)/CS = F/R
It's not the whole story when it comes to handling, but it does determine where the reach and stack should be to compliment the f/r ratio, and ultimately determine riding position.
Personally, in size larges, I've found that 1.8 is the happy number, up to 1.84. Past that cornering performance starts to suffer unless you're riding that front end like a unicycle (longer reach, lower stack).
Above 1.85 you're driving the bike with your hands and shoulders as much as your feet. Below that and you are progressively driving the bike with your feet and hips more.
My s4 stumpy is pretty short in terms of reach but with the addition of the longer CS I have a nice balance on the trail. Just having the same ratio between two bikes won’t translate to their riding the same. Reach and stack is a huge piece of what makes a bike ride well for a person of a given size.
Another big missing piece in our conversation ls here here is CoG which depends on the rider’s height and build. I think bigger riders experience bigger swings in CoG than smaller riders. They have a larger mass up top and so longer reach bikes, especially with lower stacks, will shift their CoG even farther forward. I think this does two things: one, it makes designers assume that there will be more weight on the front, and for some riders this is true. Two, it makes smaller riders not understand the plight of the large/extra large frame riders. Smaller riders are already on a balanced bike and don’t understand what it’s like having a bike that throws your CoG around as much as the long and low bikes do for say a 6 foot tall rider.
for your S2 status, you’re going to have a lot of mass getting thrown out the front of the bike when you’re in big compressions and heavy braking (edit: and less leverage to help brace yourself with your arms…) Yeah the ratio will be the same but your body mass will be interacting with it very differently. But please try it out and tell me what your experience is!!!
Yeah- I just got curious after this Jack Moir video: https://youtu.be/Kj7WuJ6d_vs?si=paQbx0AjeF3yviJc
Mostly want to test short bike vs long bike. When I do the testing- will try to normalize tires and swap the fork/front wheel between bikes to keep everything as similar as possible.
Here are the numbers:
It looks like they kept the sizing proportional.. The bigger question is will you be comfortable given the sizing differences?
I am- or at least close enough. I have a 35mm stem on the Stumpy and a 50 on the Status. Reach difference including stems is like 15mm.
Curious about the 48mm difference in wheelbase, the tiny chainstays and the mullet vs 29". Should be agile vs stable.
I mean yeah the ratios are the same but since you don’t scale with the bikes you’re going to feel completely different on them.
not trying to be the guy to beat a dead drum about something nobody cares about, but here I am - my take is that rad and rad angle are more important than front rear ratio. If you control the rad and rad angle between bikes, the difference in the ratio becomes much less pronounced. (Still preferential but I do find lower ratios better for higher speed sweeping turns, and higher ratios better for squaring off corners). Someone else alluded to it earlier or elsewhere, but bikes approaching a 1.9 ratio typically need longer stems and higher rise bars compared to their lower ratio, lower stack counterparts.
My recent lay experiments have been between a madonna and enduro... controlling the rad helps with the CoG stuff previously mentioned.
I’d argue that these are doing opposite things to achieve a similar end result. How a bike fits you in the sense of RAD or RAD angle is absolutely important, but I don’t think we can say that these numbers in isolation can replace looking at FC/RC balance. They are two different metrics that each have influence on one another.
What you’re referring to is adjusting the riders COG to suit the wheelbase balance of the bike, where as achieving a certain FC/RC balance is adjusting the wheelbase/balance to suit the riders COG in there preferred riding position.
I think the reason this is important to distinguish between is that dynamically these 2 setups will be different. While a riders COG might be balanced between the wheels, the rider themselves also has a balance point (weight distribution between hands and feet). This is where riders have been feeling the benefits of longer chainstays, and shorter reaches/higher stacks, as it aligns closer to their natural balance point while keeping the weight distribution balanced between the wheels. Using the BB as the “fulcrum” point for the riders balance point is fairly reasonable, because this is where your feel are located and you’re essentially rotating around that point with your body.
Riders with shorter legs and longer torsos tend to keep their weight more centered over the bb as they squat down. Riders with longer legs and shorter torso tend to push their hips further backwards as they squat down. The shorter legged rider has an easier time shifting their weight forward ahead of the BB, as their hips are already closer to this fulcrum. Whereas the longer legged rider has to throw some shapes and really shift their hips forward to get the same result. IMO, this is why we see such a polarizing opinion chainstay length. You have to establish where the rider feels most comfortable on the bike fit wise (ie reach, stack, RAD, etc), and the adjust where the front and rear wheels sit in relation to their body proportions and preferences.
I appreciate the detailed response, but I disagree completely.
I’m stating that if you have the same rad and rad angle, the ratio stuff becomes preference. In other words, I think that once a rider knows their preferred rad, they rip on either side of the 1.85 ratio spectrum and feel comfortable doing so.
Sure they might be maintaining the same standing body position on any bike that they've set up to have the same rad and rad angle measurements, and they're equally comfortable standing on either bike, but that does not translate to the bike having the same handling characteristics. You can't disregard the physical geometry of a bike by using Rad, you'll likely walk away with some bad results doing so. Like kapolczer implied, Rad doesn't account for a riders proportions, and that affects where your center of gravity is while riding. Whether or not you follow the Rad system is a matter of personal preference, and it's a very useful tool, but it's not the end all be all.
RAD is ergonomics. Can also effect the weight distribution but ultimately we are looking at how weight applied to the pedals is distributed to the front and rear tires. I am disinterested in systems that require me to weight the bars. The RAD “solution” you’ve outlined does not solve for riding through the feet.
I think what you mean is that where a rider weights the bike to get front wheel traction is a matter of preference. I agree with that.
https://madscientistmtb.com/rad-calc/
Im specifically referencing rad and rad angle from that calculator. I am not referring to the philosophy of fitting bikes with rad. I’m not saying that fc ratio doesn’t affect riding characteristics and not making any statements on weight distribution between the setups.
I am saying that fc ratio is confounded with other changes to bike setup and when controlling for specific bike setup (i.e. rad and rad angle), it’s easy to switch between the “long chain stay gang” and short chain stays.
Aka pick your favorite bike, toss it in the calculator then go ride another bike on the opposite end of the ratio spectrum setup to have the same rad measures. You’ll still be able to rip. Yes, they have a different feel, yes the cornering technique is different. Yes they’re suited to different riding style and terrain.
I agree it’s not the end all be all. My point is that neither is fc ratio. Standardizing rad across your bikes objectively removes one area of variation and lets the rider focus on different nuances from riding bikes at either end of the ratio spectrum.
Has anyone tried matching the rad measurement across bikes on opposite ends of the spectrum?
“…You’ll still be able to rip. Yes, they have a different feel, yes the cornering technique is different. Yes they’re suited to different riding style and terrain.”
Brother, that’s just called being good at bikes and is kind of besides the point 😂
I have no way to test this, but I really do believe front-rear ratio will turn out to be a very important metric in bike design or, better yet, bike choice going into the future. Especially in larger sizes. It won't be one value to rule them all, as someone being ABLE to ride over the front will be able to manage a higher ratio, but someone not being able to ride over the front (someone pulling back defensively) will for sure benefit from a lower ratio by having more balanced grip over the two wheels.
Saying that a correct RAD/RAAD will make you be able to ignore the chainstay length and still rip, based on the above (rider position) I do not see how that would be possible outside of having a really short front end to couple with short chainstays to get the grip. With a given RAD and RAAD, that can only mean a helluva steep headtube angle...
Also, if RAD and RAAD is SO important, you can modify it to some extent with handlebar height, stem length, bar roll, etc. But that doesn't tell you anything where that front wheel is (or the rear obviously). As above, different front-rear ratios will require different posture to weight the two correctly. Which means two different bikes with the same RAD and RAAD will have to be ridden differently. Which by default goes against the claims that the same RAD/RAAD will make two different bikes ride the same.
I'm not saying RAD/RAAD is useless (but I do not see the benefit of calculating two arbitrary values from two different arbitrary values, reach and stack, which is what RAD and RAAD is, just trigonometry with a fancier name), I'm trying to say it needs to be looked at holistically.
EDIT: regarding the calculator linked on above page, I have a pet-peeve. There are A LOT of values for handlebar geometry listed there, but as noted in the 'help' balloon, they are hard to find from the manufacturers. Better yet, the calculator obviously suggests eyeballing some values, has a black box calculation trying to estimate hand position, complicates things with grip diameter, etc., giving a very exact RAD and RAAD value, but basing everything off of VERY murky geometry. Handlebar rise is very loosely defined (it is not the total vertical height of the bar), setback is not taken into account anywhere, it's somewhat extrapolated based of how most bars look, etc. A lot of guesstimation to give you hundreds of mm and hundreds of a degree on the end result? While you could be off by milimiters based on your bar geometry guesstimation.
The technique is absolutely different, no doubt, but I’m suggesting that standardizing your rad and raad puts the rider in a position where they can perform on either side of the spectrum. I’m not suggesting to ignore chainstay length.
Still curious to hear from those who run multiple bikes across the ratio spectrum. When I tossed my bikes in the calculator, I was surprised to find they all were in a very close window from each other. That was just from my natural setup over the years, not purposely trying to match the rad values.
It wasn’t too long ago Cahal had a similar epiphany riding an ibis. FWIW I think the fc ratio is a bigger tell on what type of terrain an enduro bike is best suited for.
I wouldn’t even want the same rad on two very differently balanced bikes. Consistent rad across bikes makes zero sense as there are very different geo and body positioning needs depending on terrain and discipline. I would love the same fc/rc ratio AND rad on all my bikes, but if I could only choose one consistent variable it would be fc/rc ratio. Let the rad change depending on how I’m riding the bike.
So you haven’t tried it.
RAD is the worst addition to this thread. horrible derail.
I’ve run a single bike with a fairly large range of FC/RC ratios. Having a the ability to change the rear center +10 and +20mm means all other factors stay the same (bar, stem, spacers, etc), so having the ratio range from 1.88, 1.84 and 1.80 respectively.
All these setups rode noticeably different. And in my experience, the longer rear centre's meant a higher bar heights to achieve a similar rider balance point. All of these setups were rideable for me absolutely. But personally, the longest chainstay felt too long and I struggled to get the weight off the front wheel when I needed to, and the shortest chainstay is very active and requires a more forward riding position. I have short legs and a longer torso, so my preferences make sense to me.
So in my experience, (and without crunching the numbers in detail) I would say that a lower FC/RC ratio benefits from a larger RAD angle. The RAD length probably doesn’t change too much, but depending on the length of the RC, it would likely benefit from getting slightly shorter the longer you go. I think this is what Brian Cahal noted on the ibis he rode, that with a higher ratio, if he ran the front end lower (smaller rad angle) it was still rideable, but not his preferred position, as it’s was more aggressive over the front than he would like to be.
If you’ve found RAD to be of benefit for you when moving between bikes, that’s awesome. But I think it’s only one small piece of a larger puzzle, and the reality is that bikes have sorted out reach and stack numbers pretty well, riders have a ton of option. But it’s FC/RC that have been negatively impacted as bikes have gotten longer, and that’s what people are looking for to change on new bikes to better suit their needs.
All this talk of RAD, RAAD and FC/RC ratios brings this guy to mind: https://mistresscycles.com/
I wish there were more reviews out there for his bikes. It would be cool to see how the known commodity reviewers experience his approach to bike geometry. What limited reviews exist seem positive, but it's really just two or three guys on MTBR.
A 495 chainstay and a 435 reach on a L/XL is wild, but the wheelbase is pretty standard. New bikes seem to be creeping up closer to his stack heights, though.
Appreciate the insight. I found similar results going from -5, 0, +5 chainstay settings and playing with fork travel. I think the part about Cahal and the lower front end goes against standardizing the rad angle - would be curious to hear his and others results if it stays the same as his preferred ride. I'm squarely in the middle of size large for all my bikes, so that could influence why im not hitting the 'unrideable' limit at either end of the spectrum.
I think someone mentioned 1.85 as the inflection point earlier in the thread or in another thread. This has been my experience as well, faster trails like at Windrock and Kanuga, I prefer a lower ratio, but anything in Arizona, Oklahoma, and Arkansas where you have to generate speed/shorter downhills/natural turns, the higher ratio bike is the one I reach for.
I don't agree with RAD either tbh, and with longer chainstay bikes I'll prefer a longer bb-to-bar distance as well as a much higher bar, so I really wouldn't say that once you've got your "RAD" sorted that you can get along with a wider range of geometries. I used to think RAD was a reasonable idea, but then I rode more bikes that challenged my views. I don't think I'd go full "raised reverse", to me that seems like fucking up the cockpit of a bike so badly that you need geometry that's too extreme for most trails to fix what you've fucked up.
If RAD was the answer then my drop bar XC bike would be unrideable.
Post a reply to: Modern Geo Talk: Chainstays, Stack, Reach, and Bitching About It