going shorter crank length - any regrets

[Mark McM]

Originally Posted by Jdm

One drawback of shorter cranks per my fitter is you're asking your body to do less mobility, which can be a problem as we get older since we want more mobility.

One note here is that if cranks scaled in proportion as riders got bigger and smaller. then joint range of motion would be same for bigger and smaller cyclists. But cranks often don't scale in proportion*. For example, A 150cm tall cyclist on 150mm cranks would have the same joint angles as a 190cm tall cyclist on 190mm cranks, if the two cyclists had the exact same ratios of proportions. But most models of cranks don't come in that range of lengths, so smaller cyclists tend to ride with proportionally long cranks and with the accompanying larger range of joint angles, while taller cyclists tend to ride with proportionally short cranks andwith the accompanying smaller range of joint angles.. Perhaps the recent move to shorter cranks is simply a "correction" for people at the lower end of the height/leg length scale.


*This is part of the bike industry's mantra about bike fit - "Fit the bike to the cyclist, not the cyclist to the bike - unless it's not convenient or it cuts into profits, then fit the cyclist to the bike."

[Waldo62]

Yeah, I ride 177.5 and 180 now, but I wish I'd stuck with 190s.

[NeauDL]

I went back to 170 from 172.5 some 20 years ago and my recurrent patellar tendonitis resolved and has not been a problem again since. I think there's a good chance that going back to 170 is all the change you need.

[avalonracing]

Originally Posted by Mark McM

One note here is that if cranks scaled in proportion as riders got bigger and smaller. then joint range of motion would be same for bigger and smaller cyclists. But cranks often don't scale in proportion*. For example, A 150cm tall cyclist on 150mm cranks would have the same joint angles as a 190cm tall cyclist on 190mm cranks, if the two cyclists had the exact same ratios of proportions. But most models of cranks don't come in that range of lengths, so smaller cyclists tend to ride with proportionally long cranks and with the accompanying larger range of joint angles, while taller cyclists tend to ride with proportionally short cranks andwith the accompanying smaller range of joint angles.. Perhaps the recent move to shorter cranks is simply a "correction" for people at the lower end of the height/leg length scale.


*This is part of the bike industry's mantra about bike fit - "Fit the bike to the cyclist, not the cyclist to the bike - unless it's not convenient or it cuts into profits, then fit the cyclist to the bike."

But a random guy on YouTube said all the cool kids are riding shorter cranks this month!

[Waldo62]

Nailed it.

Originally Posted by avalonracing

But a random guy on YouTube said all the cool kids are riding shorter cranks this month!

[cuda]

Originally Posted by NeauDL

I went back to 170 from 172.5 some 20 years ago and my recurrent patellar tendonitis resolved and has not been a problem again since. I think there's a good chance that going back to 170 is all the change you need.

This thought crossed my mind. The hard part is trying to remember my knee bugged me then or not, pretty sure it was a non

[rothwem]

I'm not a big fan of going shorter than optimal for cranks. I've used 175's basically since I started riding in 2002 (I'm 6'2" with a 34.5" inseam) and I had pain in the same spot just above the kneecap just a couple years ago and I decided to try shorter cranks to relieve the pain. It didn't do anything and it felt awkward. It frustrates me that we're conditioned to look for things to buy when we have orthopedic problems on the bike. If we've been using something for a long time without issue and then have an injury, the problem is most likely the body, not the bike. Fix the body THEN worry about buying upgrades. It could be that shorter cranks could allow you to make more power, but don't change anything while you're injured, you'll lose your baseline.

You most likely have pain at the top of your knee because of torque, not range of motion. For me, it was a combination of weak hip recruitment and my ankle flexibility--the ability of my foot to "evert" was limited, so my knee tracked inwards on each pedal stroke to compensate. Weak glutes came into play here, they allowed the knee to track in instead of causing my tendons to stretch on my ankle. One of the funny things I noticed on my injury was that I would have LESS knee pain if I was hammering at relatively low cadences and more during chill rides, it was because my glutes would fire on hard efforts and stretch my ankle out, stabilizing my knee, but when chillin they wouldn't fire hard enough to put my foot in the right position.

I got a set of wide q-factor pedals to keep me riding and started doing a ****load of ankle stretching and glute strength work and I was over it in a few weeks and able to ride normal pedals.

Your root cause could be different, but I'll bet that if you set your bike up on some rollers or a trainer and watch the knee that's bugging you, you'll probably see if make a circle as it tracks out on the upstroke and in on the downstroke.

[mcteague]

I've been on 172.5 for a long time but, in the old days, rode 170s as that is what bikes came with. After a bike fit, prior to getting a custom Pursuit, the fitter said to stick with 172.5 as did Carl as I seemed to have no issues with them. I honestly wonder how people can feel the difference in 2.5mm in crank length when different bib shorts, or bibs under winter tights, can add even more than that. Maybe 5+mm... but only blind tests will convince me most of this is not in our minds.

Tim

[Mark McM]

Originally Posted by rothwem

I'm not a big fan of going shorter than optimal for cranks. I've used 175's basically since I started riding in 2002 (I'm 6'2" with a 34.5" inseam) and I had pain in the same spot just above the kneecap just a couple years ago and I decided to try shorter cranks to relieve the pain. It didn't do anything and it felt awkward. It frustrates me that we're conditioned to look for things to buy when we have orthopedic problems on the bike. If we've been using something for a long time without issue and then have an injury, the problem is most likely the body, not the bike. Fix the body THEN worry about buying upgrades. It could be that shorter cranks could allow you to make more power, but don't change anything while you're injured, you'll lose your baseline.

As a 6' 2" (188cm) rider on 175mm cranks, in effect you are already using short cranks. In proportion to your height, your cranks are analogous to a 5' 7" (170cm) rider on 160mm cranks.

Think about that that for a minute: 170cm is just about the average height of all adult humans in the world (if you consider both men and women). But the cranks found on most bikes are typically 170mm - 175, even in smaller frame sizes. This means that the majority of riders in the world are using cranks that are proportionally too long for them, and they would probably benefit from shorter cranks.

Edit: I just correct the 2nd paragraph to say "170cm is just about the average height of all adult humans in the world ..."

[Waldo62]

Originally Posted by Mark McM

As a 6' 2" (188cm) rider on 175mm cranks, in effect you are already using short cranks. In proportion to your height, your cranks are analogous to a 5' 7" (170cm) rider on 160mm cranks.

Think about that that for a minute: 170mm is just about the average height of all adult humans in the world (if you consider both men and women). But the cranks found on most bikes are typically 170mm - 175, even in smaller frame sizes. This means that the majority of riders in the world are using cranks that are proportionally too long for them, and they would probably benefit from shorter cranks.

I am all for using long cranks, but the above is not completely accurate. Cranks need to be proportional to leg length, and probably more precisely, to femur length -- the length of the lever -- not the overall height of the rider.

[dgauthier]

Originally Posted by Mark McM

(...) 170mm is just about the average height of all adult humans in the world (if you consider both men and women) (...)

I think you meant 170cm, but an average height of 170mm would be awesome to see just for a month or two...

[Mark McM]

Originally Posted by Waldo62

I am all for using long cranks, but the above is not completely accurate. Cranks need to be proportional to leg length, and probably more precisely, to femur length -- the length of the lever -- not the overall height of the rider.

When talking about populations, total height can be used as a stand-in for leg length. I don't have the data here in front of me, but the average ratio of leg length/torso length doesn't vary widely among most of the population.

(As a side note, there is myth in the cycling world that women need bikes with shorter top tubes because in proportion to their height they have longer legs than men. But there is no data to support this and plenty of data to refute it. The average ratio of leg length/torso length for women is almost exactly the same as for men. The variation in leg/torso ratio among populations of men and women vary much more widely than the average between the populations of men and women. And since we know that women are on average about 6" shorter than men, then if the average women use a crank length appropriate to the average man, the crank will be to long for woman.)

[sparky33]

Yes, I went to 165s (from 170s) and prefer it.
The spin feels more natural on the road.
A smidge more ground clearance couldn't hurt on the trail.

After a few rides and switching the majority of bikes to 165s, now the length feels normal.
I raised my saddle a few mm.

[ghammer]

I went from 175mm to 172.5mm a few years ago, and contemplate 170mm when I get a new bike this year. I had spent a significant amount of time without riding back in 2016-2017 (6mos approx), so when I resumed, my hip flexors would give me no peace, no matter what. I sized down, and the pain disappeared. Longer range of motion at the top of the stroke (12 o clock) wasn't cutting it, so the difference was worth it. The studies out there - check escape collective's latest - seem to support shorter cranks. Right now I'm at ease w 172.5, but am curious and wouldn't mind reading more about it. Thanks for posting this thread.

[JMT3]

I’m 183 cm tall with a 87.8 cm inseam. Used to ride 175mm cranks and years ago went to 172.5mm and rode better for many years. Then maybe 3 or 4 years ago read about shorter cranks and tried 165mm on one bike. I rode better and liked it. Now ride 165mm on all bike except my mtb and fatbike. On those bikesa I ride 170mm cranks. Like it, works and am staying with it. I did play with saddle height and still ride 53, 39 on two road bike, ride 52, 36 and 11-32 on my California bike. 46 oval chainring and 11.36 on my gravel bike. 34 oval and 11-50 on my fat.