Depending on bike, I have everything from 165 (track bike) to 175 (road bike). I can't really tell the difference when riding, never had any issue with hip angle or reaching desired fit, drop bar, MTB, or TT. I'm 6'3".

So while I like to follow all the theories on crank length, it so far all has had zero influence on my equipment decisions.

Maybe leg length is a better determinant?

You're tall enough that it doesn't matter - the common lengths work.
It's the under 6ft people that struggle with proportionality

I just recently switched from 172.5s down to 155s. I could tell a difference immediately but havent had a chance to ride enough to know if I like it or not. It did feel better during the fit but not sure how it will affect my power yet but excited to experiment

Height: 5 ft 11 in.
Crank length: 155mm (tri bike)

I had ridden the 172.5's that came on my bike for years. I was fitted to my bike and felt extremely comfortable. However, the top of my pedal stroke always felt a little bit tough to get over the top. I ordered 165's to try, felt great, then ordered 160's and 155's. I love the feeling of the shorter cranks. Feels like I'm spinning efficient circles instead of chopping wood leaning side to side on each stroke. My second ride on the short cranks (155mm) was a zwift race that matched my 30 min power PR. My cadence actually did not change much, less than 5 rpm increase.

ETA: I purchased Origin8 cranks from amazon for $70. Switched my bottom bracket to square taper. I was converting to 1x so it made sense to try new crank lengths at the same time.

I was having alot of hip impingement pain in aero position on stock 172.5mm cranks and did some research and found Mark from BikeSmith Design and Fabrication. He takes stock Apex 175mm cranks and can cut them down anywhere from 153.5mm to 120mm. I switched to his 153.5mm and instantly solved most of my issues and my power is much better. Cadence up a little bit. Feels like I can maintain constant power throughout stroke much easier in aero position. I also just purchased his 150mm stock No-Names and look forward to trying those out next. I also went to 165s on my road bike and I like that better than the stock as well. I am 5'8" medium frame.

I have been thinking about changing from 172.5mm to 165mm on my road bike. I'm 5'8" tall. Never had a bike fit but I feel more comfortable with a higher saddle. I'm hoping the shorter arms will help me raise my saddle a quarter inch without having to deal with knee pain from over extension.

IMO the determining factor isn't height or leg length. It's the knee/chest contact and/or hip flexibility in the aero bars. Studies have shown very little difference in power output between crank length. If you're able to sit in an optimally low position comfortable with 170mm cranks then there's not much reason to change. But if you can get lower using shorter cranks then it's probably worth going lower. Remember a 1cm difference in crank length lowers the foot by 2cm at the top of the stroke and lowers the knee by nearly as much.

A flat recommendation of 160mm across the board (based on availability) probably isn't too bad. Shorter people are probably better off with even less but they are hard to find, esp with power meters.

6'5" and been riding 175's since the dawn of time.....

Rotor.

How does a 1cm shorter crank lower the foot by 2cm at the top of stroke?

As a Junior rider and well into Senior ranks I used 177.5 (I'm 6'3"-192cm). Then switched to 175's just for ease of getting cranks for power meters. I was on 175's until 2013 when I switched to 170's on the TT/Tri bike. In the last year or so I've completely switched over to 170's across all bike mainly because I've taken to focusing on track racing. For me it's been a good change. I don't feel any difference in the length, but feel like I've got a bit more snap with the pedals. Power has gone up, but I think that's more to do with training vs length in cranks.

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

1cm added seat height + 1cm shorter crank = 2cm lower top height

My leg length (inseam) is 29.5" (or ~75cm). I rode for ~15 years or so on 170s and then made the jump to proper-sized ones.

My previous tri bike had 145mm cranks, my current one 150mm. We couldn't find 145mm's that were compatible with the bottom bracket on my QR (PR FIVE2).

I ride 160's on my gravel bike (smallest length available on a compatible crankset with GRX).

Road, gravel are all 165mm, my fat bike 170mm. Me? 6' 158 lbs 35" cycling inseam. I used to ride 172.5mm and 175mm on the fat. I like it, ride well and am not going back.

This is something I want to try as all of my bikes came with either 170 or 175mm cranks. I'm 5'4" but even at that height I have shorter legs than average. I have always felt like I'm peddling in really big circles. I would love to at least try some 165 or even 160 just to see if I really notice a difference.

You should probably be using 150mm cranks.

Also 6’5” / 195cm and have ridden 180mm on road but mainly 175mm for ease of finding cranks, especially if you use a crank based power meter. On the road bike I went to a 165mm and find it more comfortable at the top of stroke. Didn’t feel “limited” or held back by the change - 5 minutes into my first turbo session I just felt a lot smoother. I was bouncing on the saddle at higher cadence whereas I feel I stay smooth at higher cadence now.

Tri bike or road bike?

5'7" -- 155mm on tri bike, 165mm on one bike or 170mm on the other road bike(which I do want to shorten now).

On my tri bike, I was bouncing between 160mm, 155mm. Finally settled on 155mm. The stock 170/172.5 on small tri bikes only make sense from a manufactureres profit margin view.

6'3
170 on tri bikes (trial and error)
172.5 and 175 on road bikes (stock)

5’8 on 165mm tri bike , 172.5mm roadie.

New tri bike just came in 170mm. I am not planning to change it to 165mm.

The rationale has always been that in TT position, your body is more crunched up . Shorter crank arm leaves a little more breathing room.

Just some context, I do ironman and 70.3s

But again, we are talking about up to 7.5mm diff here. I personally really don’t feel any difference.

This is one thing in which I really feel it would be money well spent to get a professional fit with a fitter that can alter stroke length. I never really thought about 150mm because I hardly ever hear anything about that length. But I have been wanting to try 160-165mm to see if it's more comfortable for me.

Make sure you test all the way down to 145mm.