Morning, anyone moved from 170mm to 165mm on the road. Lots doing it for MTB, with no downside as far as I can tell. I have a dodgy hip, and I think it would benefit. May also allow me to raise saddle for a slightly more aero position, but that’s not my motivation. Do a lot of steep climbing, living near Quantocks / Exmoor so can’t really afford any loss of power/torque. Any experiences?
I have 165 on the fixed wheel commuting road bike, 170 on another, 170 on the track bike, 172.5 on race bikes and a mighty 175 on my gravel/cross bike. I don't notice any difference for a standard 32" inside leg.
raise saddle for a slightly more aero position
Normally lowering the saddle makes you more aero. My TT position is 2cm lower for the same crank length (170 mm). When the body is lower there is less frontal area, hence a lower CdA.
Avoiding crank strikes on a MTB makes some sense for a 3% loss of leverage.
170mm on the road bikes and CX, 175 on the MTB, because they came like that. Can't tell a difference.
I've got 165 on everything, road, CX, XC, big bike, training bike...
Just choose a slightly lower gear and pedal a little bit faster.
Done some big mountains in Spain, and some short sharp shocks in the UK and Sweden. It's all good.
Knee pain that i didn't know i had is fixed.
Power output is unchanged, achievable wheel torque is the same (by using a lower gear)
Normally lowering the saddle makes you more aero.
Yeah, I think the logic for aero gains was keeping saddle same but being able to lower your upper body more as your legs weren't coming up as far.
I'm fitting some 165mm cranks for the opposite reason, by raising saddle/not raising leg as much, it will require less hip flexion and hopefully less strain on low back.
I am sceptical that raising my foot a total of 10mm less will really make much difference but at least I'm upgrading stock Tiagra cranks to new 12spd 105 so marginal gains etc. 😎
I can tell difference considerably between the 172.5 I was using and the 165 I now have. I use a low fixed gear (63") so spin at a fairly high cadence and find it much nicer with shorter cranks.
Always used 165 but when using a road bike for a few months it had 172.5 Red cranks which I moved to my track frame which was a mistake as caused some hip pain that I have never had before. My knee is now coming up 15mm less (7.5mm shorter crank arm and saddle 7.5mm higher) which is quite a bit and for me was the difference between hip pain or not.
Thanks all… I figure I’ve nothing to lose and have the potential to gain… @13thfloormonk your rationale of reduce hip flexion is driving my thinking
i may pick up a cheap s/h crank initially to test on current bike before committing to nice cranks for the new build
I've got Ultegra 160mm cranks on my summer road bike. It felt weird for a bit, now it feels normal. I'm not entirely sure I can sprint as well with them though.
I also made the swap for hip pain reasons though, so I can sacrifice a bit of sprinting ability (not that it's sorted the hip pain either, but oh well...).
I swapped from 175mm to 165mm cranks in the TT bike.
Took about 10 minutes on the turbo before I forgot all about it (went to smaller front rings at the same time to balance out the effect on leverage when having to use the bottom gears on climbs (I use the TT bike on triathlons, inc lumpy ones, not traditional dual carriageway TTs).
Defo improves the comfort in terms of more being so cramped up between leg and stomach when down on the aero bars. Sort of wish I'd gone to 160mm, but they weren't available in an Ultegra crank at the time (mid pandemic).
(I'm 6ft tall and long legs too, not a complete shortarse)
Whether or there is an advantage or not with going with shorter cranks this is worth noting about range of movement.
Podcast with notes below from 35:40
https://www.fasttalklabs.com/fast-talk/how-to-keep-your-back-healthy-and-pain-free-on-the-bike/
I think if you have pain you should go and get it sorted if it's possible to rather than masking it with a shorter crank.
