I had one of my worst seasons when I switched to 165mm cranks.

I am quite little and a a bit of a spinner (cadence ~100 in a TT). I think I needed to spin faster and couldn't so my power suffered.

I am already pretty aero (CdA ~0.17) and don't think could get any hip angle improvements.

I won silver at my state masters TT the following year back on 172.5s.

I had a girlfriend who did [the Misdiagnosed Bipolar Coke Whore, to be specific]

I don't blame her, actually

It didn't last, as far as I know

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"What's your claim?" - Ben Gravy
"Your best work is the work you're excited about" - Rick Rubin

Generally riders end up spinning faster on shorter cranks. There's a few theories, one says that foot speed is held relatively constant no matter the crank length, which also makes sense as that would maintain a similar pedal force no matter the crank length.

Imagine 200mm and 100mm cranks and how much easier 100rpm would be on the little ones.

But riding what works for you is most important.

And allow time for your body to get used to the change before determining whether better or not.

I deliberately left the initial question somewhat vague, so as not to influence the answers.

I've been riding 172.5's since the dinosaurs roamed the earth. Switched to 170's about 10 years ago. I just recently switched to 165's for TT'ing. I am fortunate in having a group of about 6 Tri athlete's I train with - we typical do LSD ride's 50 to 65 miles at a pretty consistent 20 mph pace, so my power output doesn't vary much.

My legs are sore "differently" after riding the 165's - more soreness in my thighs, almost nothing in my calf's. I've had the seat up and down 5mm's, etc., nothing changes. If I put the 170's back on, it feels better with a much more balanced effort feeling between my thighs and calf's, and my legs feel better overall after the ride.

Has anyone else noticed this?

Have you also moved your saddle fore/aft when moving it up/down?

Try this: https://www.openasapp.net/...45-aa45-895ab2c18daa

Yes, plus I still ride the nose of old skool wide nosed TT saddles, so my position easily moves horizontally.

I've literally never had sore calves from riding a bike. It makes me think with the longer cranks you're having a fair bit of ankle motion. Not that the cranks are too long, just that in order to get your foot over the top you need to flex your ankle a little, or to get your foot through the bottom you need to extend your ankle a little. Either way, shorter cranks are probably just allowing you to remove that motion, which would normally be good, unless you've trained for years with a calf-heavy pedal stroke.

(it's generally better to have less ankle motion in a pedal stroke. Glutes, quads, and hammies are much stronger and slow twitch biased than gastroc/soleus)

I bike fit for a living and have helped over 2000 riders make the change to shorter cranks. The vast majority of them have self selected their length on my fit bike. Some of them have went with my recommendations if we were fitting on their actual bike. To my knowledge, three of them have went back to longer cranks.

As an independent fitter, the biggest struggle with these changes is when the client takes my fit data in another bike shop and that shops literally talks them out of the length they self selected during the fit. "But you'll lose leverage/power!" or whatever bullshit they feed them. I'm like no, we already covered that.

I was in a similar boat. Used 172.5 for around 25 years and then went to 170 and then 165. Compensated with easier gearing and all of that, opened up hip angle with higher saddle position moved aeropads moved saddle backwards et etc. Yes my RPM went up, but power went down.

The only thing that comes to mind, is that my glutes get engaged less on downstroke because I am too "open" and my hamstrings just don't work as much on a shorter lever. I can't get lower to close up hip angle because some neck injuries.

I any case, Did 2x 1 year on 165's and just felt off. I went back to 170's both times.

In my other sport, my hip flexors did a lot of work (XC skiing) so maybe I don't have the limitations of regular triathletes, and in the last 5 years, I started racing swimming masters in IM and fly so a ton of dolphin kick sets that also conditions hip flexors. So maybe I dont quite have the limitation there that others have (also given that due to neck position is already pretty upright)

I changed from a 160 back to a 165

BTW I have a 160mm R7000 Crank for sale

There’s definitely data to suggest there’s such a thing as too open.

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Jim Manton / ERO Sports

I did quit a lot of experimentation back in the day riding as low as 115mm on my commuter. I rode 162.5mm on my TT bike, 33.63 inseam. I went back to 172.5mm just to check it out, didn't take long to go back to 162.5mm. The main reason I went back to 172.5mm was I was experimenting with anything that could get my seatpost lower.

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I switched to 155s a while ago and never went back.

Rode 175mm since 1984. Tried 16Os for a year, plus moved my cleat back to midfoot.
I ride relatively low in the front, bought the hype, open up hips, blah blah blah.

Liked the midfoot, hated the 160s with the fire of 1000 suns. Power never came back up.

After a year, slapped my old 175s back on, it was like mother's milk.
Power back up to respectable levels, almost instantly.

But admittedly, I'm a different animal than you humanoids.

-bobo

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"What's good for me ain't necessarily good for the weak-minded."

I have but but can say that once Mat Stenmetz (creator of 51 Speedshop bars & Crowie's ex-coach/Carfrae's ex coach--) finally convinced me during my bike fits he did, after several of them actually-- to go shorter, I instantly increased my cycling speeds and run times off the bike. It was literally overnight. I won't be going back to longer cranks. I went to 165's from 175's. I'm 5'10". Best move I made fit wise in years was to go shorter IMO.

I'll be able to tell you in a few weeks/months - my new 165 mm crankset is waiting to replace the 172.5 mm. (84 cm / 33.5" inseam).

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"FTP is a bit 2015, don't you think?" - Gustav Iden

Keep us updated as I’m about to attempt the same. I’m 58 year old woman with 31” inseam 5’7” tall

TT bike or Road? UCI legal or no?

TT bike, I ride 150mm at 6' tall, 32" inseem. Professionally, fit by a prominent (former) FIST certified fitter (Trent Nix). Never looked back.

The difference between being correctly fit, and incorrectly fit is night-and-day.

I think Mat Steinmetz is one of the best, and stories like this always somewhat confuse me. As a 5' 10" rider on 175s, though that is not outrageous necessarily, I'd say it is likely to be the biggest thing holding you back from a world class position. As your fitter, I'd hope to see you off those for sure.

I convince very few people to go shorter. I simply guide them through an awareness building process, during which they get to choose for themselves. They almost always choose shorter. As a FIST fitter true and true, integrating cranklength selection into Slowman's brilliant fitting process was not difficult. The difficult part is the interuption of process that changing the length introduces. But there are ways to minimize that drawback, and really illicit quite an "a ha!" moment from many riders. You gotta use a fit bike to do this though, and you gotta use it correctly.

I am going to be presenting on this topic at the next FIST seminar next week. Hopeful to get a few more fitters off the "convincing" path and onto the "helping to perceive" path. I'll let you know how it goes.

Yeah 165's back to 170's on the track bike. 175's on the road bike.

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Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook

I'm afraid to ride 170's at my track :O

250 track and T4 which has a pretty low BB. Haven’t had an issue, yet!

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Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook

I haven't been on a 250 yet, will be this summer at Rock Hill.
I'm riding on a 166 with 50° corners :)