Nothing out there has as high of a suspension performance requirement as a mtb, bicycles have the highest piston speeds of ALL suspension requirements measured in inch per second not F1, not Moto GP, not motocross or supercross. Because bikes are light and there components are light, much lighter than any of the others. What we ride on is pretty incredible and it is the greatest time ever to be a mountain biker.
Nothing out there has as high of a suspension performance requirement as a mtb, bicycles have the highest piston speeds of ALL suspension requirements measured in...
Nothing out there has as high of a suspension performance requirement as a mtb, bicycles have the highest piston speeds of ALL suspension requirements measured in inch per second not F1, not Moto GP, not motocross or supercross. Because bikes are light and there components are light, much lighter than any of the others. What we ride on is pretty incredible and it is the greatest time ever to be a mountain biker.
Don't forget to add that MTB suspension also needs to handle ridiculously low damping frequencies as well (~2 to 3 Hz - pedaling), like I mentioned before.
There are basically 3 properties with tubes: OD, ID, and material. If you want to make it stiffer you can increase wall thickness or material, but since we are talking about aluminum (probably 7000 series or 6069, but probably 7000 series) then material doesn't matter as it's likely the same. Aluminum has an optimal wall thickness to diameter ratio for strength but if you are changing the diameter then your design goals are probably one or more of the following:
1. Increase strength, and by strength I mean deflection under load (which can also be accomplished by changing the wall thickness): the wall thickness of the marzocchi forks are thicker if I am not mistaken.
2. Optimize strength to weight ratio for the lowest weight possible. There are sacrifices here such as fatigue life, oscillation frequency, and deflection (aka flex).
3. Decrease or control oscillation time, or the time it takes to return to it's original position . This can also be accomplished by changing the wall thickness.
4. Eliminate backwards compatibility and used planned obsolescence as your market approach to for the years to come.
5. Create something that is different but has no tangible or measurable benefit but costs more. I have worked in manufacturing and have seen this way too many times; the product managers LOVE this.
There are basically 3 properties with tubes: OD, ID, and material. If you want to make it stiffer you can increase wall thickness or material, but...
There are basically 3 properties with tubes: OD, ID, and material. If you want to make it stiffer you can increase wall thickness or material, but since we are talking about aluminum (probably 7000 series or 6069, but probably 7000 series) then material doesn't matter as it's likely the same. Aluminum has an optimal wall thickness to diameter ratio for strength but if you are changing the diameter then your design goals are probably one or more of the following:
1. Increase strength, and by strength I mean deflection under load (which can also be accomplished by changing the wall thickness): the wall thickness of the marzocchi forks are thicker if I am not mistaken.
2. Optimize strength to weight ratio for the lowest weight possible. There are sacrifices here such as fatigue life, oscillation frequency, and deflection (aka flex).
3. Decrease or control oscillation time, or the time it takes to return to it's original position . This can also be accomplished by changing the wall thickness.
4. Eliminate backwards compatibility and used planned obsolescence as your market approach to for the years to come.
5. Create something that is different but has no tangible or measurable benefit but costs more. I have worked in manufacturing and have seen this way too many times; the product managers LOVE this.
FWIW, I think Lyrik and Pike use 7000 series upper tubes, while Yari uses 6000 series uppers. And I think it's the same for FOX (7000) vs. Marzocchi (6000).
You are right though, Young's modulus (modulus of elasticity) doesn't change here, so you won't gain any stiffness. You gain strength, but that only makes it possible to make thinner tubes that are just as strong. If you're stiffness limited, you need to increase the diameter. Since Zocchis and 36 series on FOX/M side and Yari/Lyrik on RS side use the same stanchion diameter, that's not the (primary) case here. If anything, in this case, using 7000 series would mean thinner walls (due to higher strength), causing a lighter, but at the same time noodlier fork. Which would mean failing at point 1. And winning at point 2. Point 3 is taken care of by the material damping properties, but a stiffer structure should oscillate at higher frequencies with lower amplitudes, so there is kinda a gain here. But that would mean 6000 > 7000 (due to more material being present).
I'm not touching point 4, but point 5 would, in my opinion, fall under the 'marketing gains' part of the segment.
@Jeff, re XC vs. bikepark, sadly I'm the guy that knows how suspension products are assembled and why it's so, what different parts of it do and what the dials should do and what kind of an effect they have, but for some reason I kind of fail to see the difference in settings, at least in +/-1 click kinda deal. I'm afraid I wouldn't notice the difference in these two situations, though with a back-to-back test it might be more clear. And I'm still hoping I don't see the difference because I'm too lazy to try and test all the settings and just get out and ride and focus on the riding since I'm the weak link in my bike-rider combo. Wrong thinking, but hey, if it gets me out for a ride...
And yeah, agreed regarding prototype costs and everything. But nevertheless, it seems like MTB pros run mostly off the shelf or at the worst case pre-production stuff. The inverted 40 being a case of NOT this. TBH, I've mentioned this, I'd REALLY like to see DH become the 'F1' of the sport with crazy, custom bikes. But there's not enough money in it. Currently the F1 of bike world seems to be track and triathlon racing...
Regarding friction, have you ever tried out a Lefty? I'd be interested to hear what you think about it if you have considering it has rolling bearings.
@Nico, thanks for the link, loving some of the information shared by Mojo.
Regarding how good we have it, we have it insanely awesome. But saying 'this is it' would mean we'd still be riding clunkers if guys back in the day thought the same. For how good we have it you have to thank the smartasses similar to the ones the internet thinking and talking about the stuff, but where they actually do shit and improve things :D
Regarding shaft velocities, I have The Shock Absorber handbook open (deals with the theory of designing a shock, differences between shimstacks, orifice valves, etc., but is focused towards the automotive world) and apparently 0,5 m/s is the extreme end for very high shaft speed for body motion (low speed compression/rebound) with values crossing around 2 m/s for the most extreme bumps for road cars. 5 m/s is touted as the shaft velocity where the damper will be destroyed by overloading it.
The extreme bump figure for F1/Indy cars, based on this book, is 0,4 m/s. This is not surprising for F1 at least since they deal with bumps with their balloon tyres with shocks (and inerters) only taking care of the handling - body heave, roll and pitch. And in those cases the chassis setup is usually insanely stiff in order to provide the aerodynamics with a stable platform. The switch to 18 inch tyres will change these things, but the desire for the stable platform remains. After all, the story is the same in Le Mans with the LMP1-H class, where Porsche confirmed ran a system, where the heave (up and down movement of the complete axle) and body roll damping and springing were completely decoupled using two separate spring-damper systems.
Regarding shock shaft velocities in MX bikes, I have no idea. Watching the original straight rhythm, whoops give quite an exercise to the rear shock. But looking at the likes of trophy trucks with multiplebypass shocks and burnt off stickers. But still, one of the issues in MTB suspension performance is the range in which they have to operate, both shaft speed and/or motion frequency and the range of sprung weight.
@primoz: "Regarding friction, have you ever tried out a Lefty? I'd be interested to hear what you think about it if you have considering it has rolling bearings."
I know the Cannondale and the Lefty gets a lot of hate because of the concept and the damping was hit of miss, but damn it was smooth and tracked well with those roller bearings, far better than every other XC fork. It's too bad we never got the chance at an updated Moto from Cannondale.i'd be interested to ride an inverted roller bearing fork that barely flex's without having to make the damping and spring work on the same side.
Unfortunately, as weight has become more of a concern, service intervals are shorter... Remember when Marzocchi was the smoothest fork out there? A big part of that is that they had more than 10x's the oil that we see it today's forks.. My current fork uses 10cc in the lower legs plus whatever soaked into the foam rings... That's not much..
Thankfully, a lower leg service is a cheap and quick job if you are comfortable with doing it yourself...
Maybe I should make a video of my 'lazy man's fork service.' Takes under two minutes (5 min for the extended version) and keeps the fork feeling mint in between standard service intervals.
I've picked up a few suspension and brake setup trick over the years hanging out with different EWS mechanics if there's any interest. Paging Spomer?
Maybe I should make a video of my 'lazy man's fork service.' Takes under two minutes (5 min for the extended version) and keeps the fork...
Maybe I should make a video of my 'lazy man's fork service.' Takes under two minutes (5 min for the extended version) and keeps the fork feeling mint in between standard service intervals.
I've picked up a few suspension and brake setup trick over the years hanging out with different EWS mechanics if there's any interest. Paging Spomer?
Maybe I should make a video of my 'lazy man's fork service.' Takes under two minutes (5 min for the extended version) and keeps the fork...
Maybe I should make a video of my 'lazy man's fork service.' Takes under two minutes (5 min for the extended version) and keeps the fork feeling mint in between standard service intervals.
I've picked up a few suspension and brake setup trick over the years hanging out with different EWS mechanics if there's any interest. Paging Spomer?
Maybe I should make a video of my 'lazy man's fork service.' Takes under two minutes (5 min for the extended version) and keeps the fork...
Maybe I should make a video of my 'lazy man's fork service.' Takes under two minutes (5 min for the extended version) and keeps the fork feeling mint in between standard service intervals.
I've picked up a few suspension and brake setup trick over the years hanging out with different EWS mechanics if there's any interest. Paging Spomer?
do it! why are you waiting for me? we coulda been done by now if it only takes 2 minutes! : )
Maybe I should make a video of my 'lazy man's fork service.' Takes under two minutes (5 min for the extended version) and keeps the fork...
Maybe I should make a video of my 'lazy man's fork service.' Takes under two minutes (5 min for the extended version) and keeps the fork feeling mint in between standard service intervals.
I've picked up a few suspension and brake setup trick over the years hanging out with different EWS mechanics if there's any interest. Paging Spomer?
Nothing out there has as high of a suspension performance requirement as a mtb, bicycles have the highest piston speeds of ALL suspension requirements measured in...
Nothing out there has as high of a suspension performance requirement as a mtb, bicycles have the highest piston speeds of ALL suspension requirements measured in inch per second not F1, not Moto GP, not motocross or supercross. Because bikes are light and there components are light, much lighter than any of the others. What we ride on is pretty incredible and it is the greatest time ever to be a mountain biker.
This is both true and false. Yes, mtb suspension has to be very precise due to the direct connection the rider has to the bike. Without a motor to muddy the water with a bunch of vibrations most riders can feel any sloppiness in the suspension. This is why most fork bushings are too tight, the manufacturers would rather add some friction than the perceived defect of bushing slap.
I haven't measured F1 or MotoGP, but between mtb and moto it's not even close. Moto shaft speeds are so much higher.
also TAKE PART IN OUR INSIDE LISTENER RESPONSE!
this week's question:"has mountain bike design peaked? is bike design as good as it gets?"
email me your audio response via phone voice recorder (preferred) or email me your written response and i'll read it. deadline is this sunday for this question. sspomer@vitalmtb.com
a rad look back at mondraker over the years w/ all their DH bikes riding val di sole.
https://www.vitalmtb.com/news/press-release/20-Years-of-Winning-Mondrakers-History-of-Building-Incredible-Mountain-Bikes,3426
[img]https://p.vitalmtb.com/photos/forums/2020/03/04/9275/s1200_mondraker.jpg[/img]
this wasn't in there (fabien's canberra...
this wasn't in there (fabien's canberra DH bike from 2008 or 2009 or whenever that was...today's enduro bike?)
Absolutely not today’s enduro bike - interrupted seat tube, no bottle cage, rims aren’t carbon, plus I’d probably rip that derailleur off when shifting into my 51t cog.
Curious what maximum moto shaft speeds are. I have no idea.
Yeah - just the vehicle speed and longer stroke would make me think at least 4-5x higher, with an off-road (Baja, XC, Dakar) maybe being 10-15x higher.
Not to mention, mountain bike wheels are so much larger and mountain bikes so much lighter (more vertical deflection) that I would imagine mtb wheels skip over the top of a lot more trail minutia. Put another way, when I smash a rootball on my mtb - I catch a little air unless I intentionally squash it. When I do the same on my KTM 300, I only catch air if intentionally pop it.
Last comment - mtb suspension is too sensitive to maintenance. Most new money in the sport (young professionals) doesn’t have time to drop their bike off for service every few rides (or DIY). At the same time, most new money only needs rebound and air spring adjustment. I think there’s opportunity for a broad scale simplification of suspension in the industry to improve service life and reduce cost with limited impact to system weight.
My comments should have extra clout over the average forum member because I
1). ride moto (mostly klunkers until 2014 - then got too busy to ride in ~2018).
2) I used to work in the industry (shop rat)
3), and I now work in aerospace (so what if it’s just business system IT?).
I can execute air can and fork lowers 50h service on a 'normal' garage workbench in about 1 hour. You'd certainly need to practice a few times to get good at it, but it doesn't seem out of reach for an enthusiast to do a few services each season.
Check out Honda recommended service intervals on a 450RX:
Nothing out there has as high of a suspension performance requirement as a mtb, bicycles have the highest piston speeds of ALL suspension requirements measured in...
Nothing out there has as high of a suspension performance requirement as a mtb, bicycles have the highest piston speeds of ALL suspension requirements measured in inch per second not F1, not Moto GP, not motocross or supercross. Because bikes are light and there components are light, much lighter than any of the others. What we ride on is pretty incredible and it is the greatest time ever to be a mountain biker.
This is both true and false. Yes, mtb suspension has to be very precise due to the direct connection the rider has to the bike. Without...
This is both true and false. Yes, mtb suspension has to be very precise due to the direct connection the rider has to the bike. Without a motor to muddy the water with a bunch of vibrations most riders can feel any sloppiness in the suspension. This is why most fork bushings are too tight, the manufacturers would rather add some friction than the perceived defect of bushing slap.
I haven't measured F1 or MotoGP, but between mtb and moto it's not even close. Moto shaft speeds are so much higher.
Except that today clearance in forks is something normal while I sold off a 7 year bike with the original Pike with two services done on it with no clearance in the bushings.
And it's not just rock shox that has bushing clearance, it's also Fox based on what I'm told.
Plus that clearance is a factor in giving you binding under load since you're loading the edge of the bushing and scratching your uppers instead of sliding on the whole surface of the soft, smooth Teflon of the bushing. Ans the clearance loads the seals more as well.
Bushing clearance is a cop out so the parallelness and distance tolerances for both the uppers (sliders pressed into the crown) and lowers can be slacker. Tighter tolerances are more expensive, but produce a fork with less clearance.
And while a tighter bushing will cause more stiction in the parking lot, it should perform much better with a flexing load applied to it.
Maybe I should make a video of my 'lazy man's fork service.' Takes under two minutes (5 min for the extended version) and keeps the fork...
Maybe I should make a video of my 'lazy man's fork service.' Takes under two minutes (5 min for the extended version) and keeps the fork feeling mint in between standard service intervals.
I've picked up a few suspension and brake setup trick over the years hanging out with different EWS mechanics if there's any interest. Paging Spomer?
I hope it's not the stick a zip tie under the seal and apply a lubricant under it trick. That just brings more dirt into the oil seal and bushing, scratching the uppers. And the choice of lubricant can be an issue as well.
Darren had a few things to say in the linked podcast about this as well if I'm not mistaken. As in don't do it.
I can execute air can and fork lowers 50h service on a 'normal' garage workbench in about 1 hour. You'd certainly need to practice a few...
I can execute air can and fork lowers 50h service on a 'normal' garage workbench in about 1 hour. You'd certainly need to practice a few times to get good at it, but it doesn't seem out of reach for an enthusiast to do a few services each season.
Check out Honda recommended service intervals on a 450RX:
WOW
This is actually why I was pushing for "descending time" not just "ride time".
Lots of manufacturers will spec an interval for trail riding and an interval for racing. Trail riding usually has something like a 4-5x multiplier on it.
I'd say if mountain bike was counting "descending hours" the same way Honda is counting "races", mountain bikers would be looking at a total fork freshen up every 10 hours of riding or less.
Nah won’t be for another few weeks, possibly months. This will be the 2021 lineup so if they follow the trend it will be released together with the new shocks and 38 this April/may
1. Increase strength, and by strength I mean deflection under load (which can also be accomplished by changing the wall thickness): the wall thickness of the marzocchi forks are thicker if I am not mistaken.
2. Optimize strength to weight ratio for the lowest weight possible. There are sacrifices here such as fatigue life, oscillation frequency, and deflection (aka flex).
3. Decrease or control oscillation time, or the time it takes to return to it's original position . This can also be accomplished by changing the wall thickness.
4. Eliminate backwards compatibility and used planned obsolescence as your market approach to for the years to come.
5. Create something that is different but has no tangible or measurable benefit but costs more. I have worked in manufacturing and have seen this way too many times; the product managers LOVE this.
https://singletrackworld.com/2020/02/teased-new-ext-era-fork/
You are right though, Young's modulus (modulus of elasticity) doesn't change here, so you won't gain any stiffness. You gain strength, but that only makes it possible to make thinner tubes that are just as strong. If you're stiffness limited, you need to increase the diameter. Since Zocchis and 36 series on FOX/M side and Yari/Lyrik on RS side use the same stanchion diameter, that's not the (primary) case here. If anything, in this case, using 7000 series would mean thinner walls (due to higher strength), causing a lighter, but at the same time noodlier fork. Which would mean failing at point 1. And winning at point 2. Point 3 is taken care of by the material damping properties, but a stiffer structure should oscillate at higher frequencies with lower amplitudes, so there is kinda a gain here. But that would mean 6000 > 7000 (due to more material being present).
I'm not touching point 4, but point 5 would, in my opinion, fall under the 'marketing gains' part of the segment.
@Jeff, re XC vs. bikepark, sadly I'm the guy that knows how suspension products are assembled and why it's so, what different parts of it do and what the dials should do and what kind of an effect they have, but for some reason I kind of fail to see the difference in settings, at least in +/-1 click kinda deal. I'm afraid I wouldn't notice the difference in these two situations, though with a back-to-back test it might be more clear. And I'm still hoping I don't see the difference because I'm too lazy to try and test all the settings and just get out and ride and focus on the riding since I'm the weak link in my bike-rider combo. Wrong thinking, but hey, if it gets me out for a ride...
And yeah, agreed regarding prototype costs and everything. But nevertheless, it seems like MTB pros run mostly off the shelf or at the worst case pre-production stuff. The inverted 40 being a case of NOT this. TBH, I've mentioned this, I'd REALLY like to see DH become the 'F1' of the sport with crazy, custom bikes. But there's not enough money in it. Currently the F1 of bike world seems to be track and triathlon racing...
Regarding friction, have you ever tried out a Lefty? I'd be interested to hear what you think about it if you have considering it has rolling bearings.
@Nico, thanks for the link, loving some of the information shared by Mojo.
Regarding how good we have it, we have it insanely awesome. But saying 'this is it' would mean we'd still be riding clunkers if guys back in the day thought the same. For how good we have it you have to thank the smartasses similar to the ones the internet thinking and talking about the stuff, but where they actually do shit and improve things :D
Regarding shaft velocities, I have The Shock Absorber handbook open (deals with the theory of designing a shock, differences between shimstacks, orifice valves, etc., but is focused towards the automotive world) and apparently 0,5 m/s is the extreme end for very high shaft speed for body motion (low speed compression/rebound) with values crossing around 2 m/s for the most extreme bumps for road cars. 5 m/s is touted as the shaft velocity where the damper will be destroyed by overloading it.
The extreme bump figure for F1/Indy cars, based on this book, is 0,4 m/s. This is not surprising for F1 at least since they deal with bumps with their balloon tyres with shocks (and inerters) only taking care of the handling - body heave, roll and pitch. And in those cases the chassis setup is usually insanely stiff in order to provide the aerodynamics with a stable platform. The switch to 18 inch tyres will change these things, but the desire for the stable platform remains. After all, the story is the same in Le Mans with the LMP1-H class, where Porsche confirmed ran a system, where the heave (up and down movement of the complete axle) and body roll damping and springing were completely decoupled using two separate spring-damper systems.
Regarding shock shaft velocities in MX bikes, I have no idea. Watching the original straight rhythm, whoops give quite an exercise to the rear shock. But looking at the likes of trophy trucks with multiplebypass shocks and burnt off stickers. But still, one of the issues in MTB suspension performance is the range in which they have to operate, both shaft speed and/or motion frequency and the range of sprung weight.
I know the Cannondale and the Lefty gets a lot of hate because of the concept and the damping was hit of miss, but damn it was smooth and tracked well with those roller bearings, far better than every other XC fork. It's too bad we never got the chance at an updated Moto from Cannondale.i'd be interested to ride an inverted roller bearing fork that barely flex's without having to make the damping and spring work on the same side.
Thankfully, a lower leg service is a cheap and quick job if you are comfortable with doing it yourself...
I've picked up a few suspension and brake setup trick over the years hanging out with different EWS mechanics if there's any interest. Paging Spomer?
And then connect it wirelessly to my neural network so I can think to change gears/dropper & suspension settings...
https://www.vitalmtb.com/news/press-release/20-Years-of-Winning-Mondrak…
this wasn't in there (fabien's canberra DH bike from 2008 or 2009 or whenever that was...today's enduro bike?)
I haven't measured F1 or MotoGP, but between mtb and moto it's not even close. Moto shaft speeds are so much higher.
https://www.vitalmtb.com/features/Chris-Canfield-of-Suspension-Formulas…
also TAKE PART IN OUR INSIDE LISTENER RESPONSE!
this week's question: "has mountain bike design peaked? is bike design as good as it gets?"
email me your audio response via phone voice recorder (preferred) or email me your written response and i'll read it. deadline is this sunday for this question. sspomer@vitalmtb.com
Not to mention, mountain bike wheels are so much larger and mountain bikes so much lighter (more vertical deflection) that I would imagine mtb wheels skip over the top of a lot more trail minutia. Put another way, when I smash a rootball on my mtb - I catch a little air unless I intentionally squash it. When I do the same on my KTM 300, I only catch air if intentionally pop it.
Last comment - mtb suspension is too sensitive to maintenance. Most new money in the sport (young professionals) doesn’t have time to drop their bike off for service every few rides (or DIY). At the same time, most new money only needs rebound and air spring adjustment. I think there’s opportunity for a broad scale simplification of suspension in the industry to improve service life and reduce cost with limited impact to system weight.
My comments should have extra clout over the average forum member because I
1). ride moto (mostly klunkers until 2014 - then got too busy to ride in ~2018).
2) I used to work in the industry (shop rat)
3), and I now work in aerospace (so what if it’s just business system IT?).
.... ;-)
So serious.
Check out Honda recommended service intervals on a 450RX:
WOW
And it's not just rock shox that has bushing clearance, it's also Fox based on what I'm told.
Plus that clearance is a factor in giving you binding under load since you're loading the edge of the bushing and scratching your uppers instead of sliding on the whole surface of the soft, smooth Teflon of the bushing. Ans the clearance loads the seals more as well.
Bushing clearance is a cop out so the parallelness and distance tolerances for both the uppers (sliders pressed into the crown) and lowers can be slacker. Tighter tolerances are more expensive, but produce a fork with less clearance.
And while a tighter bushing will cause more stiction in the parking lot, it should perform much better with a flexing load applied to it.
Darren had a few things to say in the linked podcast about this as well if I'm not mistaken. As in don't do it.
Lots of manufacturers will spec an interval for trail riding and an interval for racing. Trail riding usually has something like a 4-5x multiplier on it.
I'd say if mountain bike was counting "descending hours" the same way Honda is counting "races", mountain bikers would be looking at a total fork freshen up every 10 hours of riding or less.
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