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“…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.
RAD is really just the concept of spread, with extra steps. Spread (somewhat used before rad) is just the length of the hypotenuse of the triangle formed by reach and stack.
Its important as it determines "fit" and overall body position, but without FC/RC head angles, BB drop etc, it is useless by itself.
Upon further reflection, I can see that rad actually belongs in here, even though it mainly relates to ergonomics
Scroll on back, homie. I posted about mine in this thread a while ago. Happy to answer any additional questions. (It rips.)
FWIW, I think the fact that Lee McCormack, the guy who invented RAD/RAAD, is designing bikes which make Brian Cahal sound like Dave Weagle should put all the “all you need is RAD” talk to bed.
Can you explain that last line?
On page 10 of this thread, notanengineer said: "my take is that rad and rad angle are more important than front rear ratio”
I think that’s wrong not just for the reasons that folks replied with but also because Lee (the guy who invented the concept of RAD/RAAD) is designing bikes with extremely low front/rear ratios.
(Brian Cahal is the public face of the Long Chainstay Gang, Dave Weagle is a famous member of the 430mm Is More Than Enough Clan.)
i‘m sorry, but he also invented the riprow…
Ok I get it now, and agree with all points. Lee is corny but I can get behind his mission.
my argument was that rad matters for fit, that ratio matters for rider preference/terrain, and controlling rad makes it easier to understand the differences between either end of the ratio spectrum. there was no 'all you need is rad' narrative.
I always thought that the idea behind the RAD measurements were to get s similar cockpit feel between different bikes..
it sounds like RAD is like getting your ski boots fit and knowing exactly what size you are.
fC/RC ratio is what style of ski boot you want, in that size.
RAD is boot fitting. FC/RC is mounting location of bindings
Got a good ride in on the short bike... I'm surprised at how much different it feels even though in my head 48mm (difference in wheelbase from my normal bike) is not that big of a % change.
Anyway- this thing feels great to me- seems to be able to carve switchbacks (we have a lot) instead of just steering around them. Also more poppy and fun to ride.
Will have to do more setup work to get comfortable- needs grips, taller bars and more gears. After I'm comfy- will try to do a real back to back with my other bike and time some sections.
But what if I like centre-mounted skis but my bike's F:R ratio is 1.89 and I like that too?
What's up with that rear derailleur 😁
How tall are you?
5'11"
I think skis being center mounted is easier for people to understand. Like, if you want to ski park and ski switch center mounted for sure. If you like the way a ski carves when it’s center mounted that’s a little more esoteric. Same with bikes. People who like a more centered stance like the way that the bike carves when your weight is more balanced. I feel like the front end of long front center bikes “swing around” similar to how a long stem feels on a road bike. There isn’t really a riding switch equivalent on mountain bikes and so the difference between the ratios is a little more subjective I suppose.
Yeah I was being silly. Centre mounted skis and long chain stays don't have a lot in common.
You still don't mount the bindings all the way back on carving skis. You need a bit of tail to give you support from behind. It's analogous to the front and rear end of a bike, maybe a bit different due to the bike having two contact points while a ski has a surface contact and bends.
I’ve had ski shops give me a lot of shit for mounting my bindings further forward than manufacturer recommended, just like we hear lots of people complaining about long chainstays making bikes unrideable
Post a reply to: Modern Geo Talk: Chainstays, Stack, Reach, and Bitching About It