I managed to get a cracking deal on a set of 170mm SRAM X01 cranks in the recent sales (less than half price).
At 6ft tall with a 34" cycling inseam, every proper MTB I have ever owned going back to 2010 has come with 175mm cranks, but with shorter cranks being the latest trend I thought I'd give them a blast.
One ride in, I definitely notice a touch of top end pedaling grunt is missing but other than that, things feel nice. This is on an XC / trail bike that gets pedaled a lot (Tansition Spur).
I'd be interested to know what others here think of the whole crank downsizing thing.
Can't say I noticed any difference really. Currently running 165 & 170 on mtb's, not sure what the road bike has actually.
I'm about the same height and inseam. I have bikes with both 170 and 175 cranks. I can't tell the difference just riding them. I prefer shorter cranks just for the ground clearance. The actual leverage difference is less than 3%.
Back to back from 175mm to 170mm I felt they took a few rides to get used to pedalling up hill, but not much more than that.
Can’t say I noticed any difference really. Currently running 165 & 170 on everything
This. Am 6’
170mm on 3 'road' bikes, 175 on MTB's. Can't tell.
Did you adjust your saddle height to accommodate (5mm higher)?
I couldn't notice any difference between 175 and 170.
I'm not a fan.
3% torque doesn't sound much. But then sit on a turbo trainer and pedal at your natural cadence at your FTP, then try and hold one 3% higher (same power output), it's harder work, and that's how much harder you're having to work for the same output.
And perception wise, it's always felt like it's the wrong gear, like the range of cadences you can pedal has narrowed considerably. Like I've lost the torque at the bottom end, but haven't gained anything at the top so always closer to spinning out.
If your average height or shorter then maybe it's a benefit.
The only places I like them is both fixies/track bikes have them to prevent the jackhammer feeling when you hit your max cadence.
That would probably make sense for your height and inseam (there are calculators out there). I’m 5’8 with a 29-30” inseam and notice the difference between sizes.
I’m currently running 165mm on my mtb and 160mm on my commuter. I like the 160s more and may try a Hope 155mm set on my mtb soon.
I know I’m supposed to get less power from the shorter lever, but actually I feel like I get more because I’m using my leg muscles in the right position. Climbing felt easier on my mtb when I dropped from 170mm to 165mm (without changing the chainring).
3% torque doesn’t sound much. But then sit on a turbo trainer and pedal at your natural cadence at your FTP, then try and hold one 3% higher (same power output), it’s harder work, and that’s how much harder you’re having to work for the same output.
It's not that simple though. You don't actually have a "natural cadence", your cadence changes depending on the demands of the situation. With shorter cranks, you will tend to use lower overall gears longer. The difference is the biomechanics of how your legs and muscles work. A 3% difference will mostly just be lost in the noise if you tried to research it.
One ride in, I definitely notice a touch of top end pedaling grunt is missing
I'd put money on you not being able to tell the difference in a blind test.
"I’m not a fan.
3% torque doesn’t sound much. But then sit on a turbo trainer and pedal at your natural cadence at your FTP, then try and hold one 3% higher (same power output), it’s harder work, and that’s how much harder you’re having to work for the same output.
And perception wise, it’s always felt like it’s the wrong gear, like the range of cadences you can pedal has narrowed considerably. Like I’ve lost the torque at the bottom end, but haven’t gained anything at the top so always closer to spinning out.
If your average height or shorter then maybe it’s a benefit."
Have you spent any time riding shorter cranks?
I have 165mm cranks on both bikes (e-full-sus and singlespeed hardtail) and long legs for my height (33.5"). With the right gearing I've found zero downsides. The shorter the cranks, the higher your natural cadence, so unless the cranks are incredibly short you have no loss of power.
If you regularly use your granny gear, then switching to shorter cranks will require you to change to a smaller chain ring to optimise your gearing. You'll also need to raise your saddle height.
Geez, since when was 170mm considered short? I've run 170 for years on all my off road bikes, except single speed which came 180mm but were switched a year or so later to a nicer set which were 170mm and most of my road bikes have came with 175mm. Could not tell any difference between any of the sizes. Last mtb came with 165 and noticed no difference either, but with a very low bb, I was getting a lot of pedal strikes. Bought a set of 155mm Hope and on the first ride I did notice a difference in pedalling. Can't say it was worse or better but definitely different/unusual. Now I'm used to them I don't notice any difference swapping back and forth between bikes. Have never felt the need to change gearing either but did have to raise the saddle a bit. What I have noticed is a lot less pins in my pedals needing replaced. Seems less fatiguing in legs when doing long descents as well, although I did get them in the height of the riding season though, so this could be just to being more bike fit.
Short version, wouldn't worry about it, you'll be fine.
I bought some 165s (in fact two sets) to reduce pedal strikes
I moved from 175mm
And absolutely hated them - so bought some 170mm which are fine. I just felt I lost too much leverage
165mm on the full sus, 175mm on my old hardtail (coz that was the done thing back then). Can't really offer a direct comparison, full sus has 29" wheels, is 1x12 (32 - 10-51) and probably weighs 2.5 - 3kg more than the HT, which is 26" wheeled, and running 3x9 gears..
I would like to find an old m770 crankset at 165mm for the HT though; I think my knees would appreciate it.
Crotch to floor 34" and love 165mm cranks, I'd like to see 160mm more available as 155mm might be a bit too small but unless I test them it's just a guess, I can definitely tell the difference when jumping on a mates bike with 175mm, the main benefit for me is less hip and knee pains as well as improved climbing ability and clearance.
Ran 170 for years, 5-9 height as that was the size available. Some suggested, taller riders use larger cranks.
Do not adjust sadle height if you run different crank lengths. Only ended up with 175 on the MTB's as that's what I got. It's fine as riding the two MTB's at 175 is different from the road/CX at 170.
Really don't know what you lot are fusing about - been pedalling 'properly' for best on 40 years now. Latest 'fads'.
I'm 6'3" 34 inside leg.
Have run 175s for years then got an eeb with 165 on. I could tell the difference straight away, but no real concerns about power delivery because it's an eeb!
Then I decided to take my trail/enduro bike down to 165 to reduce pedal strikes mainly. I also went from 30t to 28t ring at the same time, to make up for the loss in leverage through faster RPM.
Felt weird at first but now I am used to it I much prefer it. I can spin a lot faster, my legs seem less tired as a result.
The only negative for me was the time taken to adjust pedalling style (didn't take long so not really much of a downside!).
I tine trialled on 170 cranks and use 155 on my mtbs.
Really don’t know what you lot are fusing about
For me it’s an absolutely massive increase in comfort - a very close second to stem length/bar height. I get knee pain with 175mm cranks and much greater comfort going below 170mm. On a new bike I usually change the cranks before the saddle.
Power is torque x RPM. The theory with shorter cranks is that the RPM will increase along with torque decreasing giving same power. If you are not increasing RPM then you are losing.
I prefer shorter cranks as ride fixed gear and can hit 200rpm downhill which is noticeably more comfortable on 165 versus the 172.5 I currently have (which I only have because I picked up some SRAM Red carbon cranks for £80 and am too tight to pay more for 165 but I really will have too as I do notice the difference)
Moved my FS to 165's from 175's a few years ago to reduce pedal strikes, dropped to a 30T (from 32) front ring to compensate.
Just moved my eeb to 165's too, as it was in for a new motor - did 30 miles yesterday, definitely less 'clipping' of pedals.
Another advantage is that I can fit longer droppers to both bikes - when the current ones 'die'.
36" inseam.
To be fair you do actually need a longer dropper with shorter cranks.
10mm shorter cranks means putting your seat up 10mm, so you need 10mm more drop to get your dropped saddle height back to where it was.