I ride 155s. I know when my fitter put me on the smaller cranks, it felt A LOT better. My hips were less pinched at the top of my stroke. I suppose it does help me breathe better, but I've always been on short cranks for tri so i dont have anything to compare to.

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Strava

All pluses without any minuses is always a sign of mis-information. But I use slightly shorter cranks than normally recommended (at 6'2", I am recommended at 175+ but my fitter put me on 172.5) and I think it's helped my cadence, balance and smoothness. I doubt I could go any shorter or I'd feel like i'm riding a tricycle.

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808 > NYC > PDX > YVR
2024 Races: Taupo

Your leg length could be a relevant consideration

https://www.sheldonbrown.com/cranks.html

i'm down to 155s and it's the most comfortable i've ever been on the bike. i'm 6ft tall. i'm selling a cobb 160mm in the classifieds if you're interested in trying them out ;)

I am 6' tall with long legs and have trialled from 177.5 to 150 cranks and have settled on 160. Each time I went down by 5mm it just felt better until 160 for me. I feel like I can engage with the pedals through more degrees of the pedal stroke. At 150 it felt good to a point but a lot more stress on my lower back to maintain power over a longer period and hurt my run. If you follow what's going on although minor Frodeno has gone from 172.5 to 170 in the last year and after a long period of convincing Chris Lieto went from 175 to 170 and rode his fastest Kona split ever. Regardless the science and feeling I agree with. Have a read of this article it has some interesting stuff...

https://www.powercranks.com/cld-more.html

I'm 5'9'' and went from 172.5mm to 150mm since more than a year ago, and not planning to go back to larger cranks.

For me the significant difference was lot more comfort on a TT bike on an aggressive solution, I don't have any flexibility so it really made a difference for me in that aspect.

No change in either cadence or power at all.

5'9"ish here as well - just moved from 172.5 to 155 last week.

My previous position was pretty aggressive but not sustainable - I feel more powerful/comfortable/aero with the shorter cranks, but so many variables were changed in my fit session that I can't attribute all of the improvement to crank length. I do believe it contributed quite a bit, though.

Racing this weekend for the first time with the new fit - so I guess this will be the true test!

Lot of good prior threads on here about it. Basically the body is pretty adaptable. I have ridden from 115mm to 175mm. I am on 162.5mm. I tried to go back long 172.5 for experimentation purposes but I couldn't handle it. I rode 165mm on my road bike and MTB as well. It hasn't seem to slow down Lional since he went from 172.5mm to 165mm, or Weiss, or any number of the other short cranks pros. Starky and Sebi still ride 175mm.

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Interesting this has been my experience, 155s feel just a tad too short and after a long ride I feel my legs have suffered a bit. But I've adapted a little better to them now and the position I am able to hold with the 155s is much better.

I still don't buy the hype. I can move my heel up/down 5mm for fit purposes and not buy new cranks. I know this is going to stir things up and it's not my intention to make people upset about using something that works for them.

Yes, I have tried shorter cranks, I'm 161 cm tall and ride 170's.

John Cobb is awesome, his work is among the best but some of these claims are really reaching...

MORE EFFICIENT BREATHING
5mm makes breathing 3% more efficient? If only breathing was a limiter.

INCREASE SEAT HEIGHT
How does that make you more aero?

GET MORE AERO
Why couldn't you lower your front end? I'm seeing bikes getting taller.

DEAD SPOT ELIMINATION
Uhmm...what? I need explanation on that one.

ELIMINATE KNEES IN THE CHEST
Again 5mm? I can move my ankle that much for free. I understand that tests have been done and shown that there is not a reduction in power for much shorter cranks so if you cannot move you ankle that far, maybe shorter is right for you.

REDUCE TOE OVERLAP
OK, I'll give him that one.

MATCHING RUN CADENCE
I recall many top long distance riders using a low cadence on the bike, why would they want to change?

Totally agree

im 5'6" and ride 145mm cranks, best thing iv ever done on the TT bike.

Position is better and less stress on the joints in hip.

Also 82ks so tummy doesn't get in the way as much.

I am about 5'9''-5'10'' and I debated this subject for awhile and had 172.5 on my tri bike and earlier this year went to 170's, but still didn't feel that much difference. Finally, I switched to 165's and find it was the right move. I can't point to an increase to power the past 6 months to this change since I've had a good training block, but it definitely feels smoother around the pedal stroke.

I got another bike fit to get another opinion and they tested my R/L balance and said it was 50/50 (or very close). They said I made the right choice and I feel better. Though, I think if you are racing a hilly or technical course then I'm not sure if it's that easy with shorter cranks. I'm doing a "flat" course in Copenhagen this year so I think the shorter cranks should help since I think I'll just need to stay aero and efficient.

I kept my road bike with 172.5's and feel comfortable spinning 90-95. I think the more important change on the road bike was switching to semi-compact cranks (52-36) to have a wider range for different courses and situations.

I could never tell a difference from 150 to 180, ymmv. I use short ones on my track bikes and longer on my tt bike, pretty much whatever I have laying around on road bikes.

fwiw, my old Cobb crankset (it was one of the first ones) is just a re-badged Shun crank. (actually it still says Shun on it...)

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I am 6'2" and am challenged from a hip and hamstring flexibility standpoint. Paraic at Cyclologic did my TT fit and put me in 155s on my Felt IA. I have 165 on my road and cyclocross bikes. Recently bought another road bike (used) with 175 and have changed to 170 (as short as I could get with Campy.)

I am a little embarrassed to say that I feel very little difference between the bikes. I do think that on the tt bike the 155s are helpful mitigating the lack of flexibility when in aero. On the other bikes, I hardly notice the difference.

We loaned a bike with 155s to a friend who has ridden 170s for decades. I setup the saddle height to replicate the extension she had with her 170s. After riding several days I asked how she liked the 155s. She was surprised to hear that they were a different length than her normal cranks and thought they were just fine. We're talking someone who has qualified and raced Kona every year for well over a decade. So for her at least NBD.

YMMV,

Hugh

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Genetics load the gun, lifestyle pulls the trigger.

I'm considering moving to shorter cranks on my TT bike to experiment a bit. I currently have a 172.5 ultegra 6800 crankset and ultegra di2 on my bike. My question is, if I want to go down to 165 while trying to minimize cost would picking up shimano 105 5800's in 165 be a big drop in quality vs. the ultegra 6800?