So, while I'm "only" 6 feet tall, my cycling inseam is 36" (or 914.4mm for those who think in metric). I'm told that this is kinda on the high side of average... At this point, I've spent most of my miles on 170mm cranks and some 175 now. Obviously it works, but, given that my leg length puts me into the upper end of frame sizes, I'm kinda wondering about trying something longer. 180mm or maybe more? Before dropping the money on this, I was curious about the experience of others with long legs, have you tried going longer on the cranks and if so what did you find?

37.25" inseam here, and use 175mm and 177.5mm cranksets. Unless you are a low RPM masher, I wouldn't recommend longer than 175mm.

^^ Similar measurements and also on 175, except 170 on my SS/FG. Agree with above. I know if you go to Zinn's website you will be told you should be using 190's or something crazy like that but honestly I think our body adapts to whatever crank length you are using.

But it is weird many bikes only come with 170 - 175mm cranks, from the smallest to the biggest frame size, 47-62cm. That is not even 3% difference in crank length, even if the frame size differ more than 30%. For sure many small bikes come with too long cranks, even expensive bikes, but Im not sure 180mm rather than 175mm will make any difference to a tall rider (Im not one).

I noticed it when I used 180mm cranks on my old TT bike, and I did't like it.

177.5mm worked better, but 175mm works best for my primary road bike.

Not as tall, I have a bike with 180 cranks, and several others shorter ..
I'm not trying to either spin or ride fast .. ..

Lennard Zinn, Makes bikes for even taller folks , got a source to make 200+mm crank arms for him..



....

I'm a bit shorter than you,with more in the torso than the legs. But, I like my 180's. I definitely wouldn't go any longer though. Plus, few cranks are readily available longer than 180.

You run into two factors.

Longer --> more leverage.
Longer --> longer circle of movement, and thus slower overall cadence.

It probably doesn't make much difference in actual power either way, and I ride bikes with both 175's and 180's with hardly noting the difference.

IRD makes longer cranks. I thought they were available in several lengths, but it appears as if only in 200mm. Those would still be really long!!!

https://store.interlocracing.com/irdexlocrar.html

I used to be lower RPM when I was much younger (like middle school) and not full height yet. Not sure if it was a height thing or an experience thing or what. Currently, I tend to run 100-110 and find lower cadences difficult at higher load.

Yup, Zinn would have something crazy that probably scrapes the ground unless I use a BB height from a MTB. There are other fit calculators that put me closer to 177.5 or 180 though.

I agree that the body can adapt to a lot, but there is also something to be said for the machine being set up for the body to perform at its peak. Being as I'm a bit outside the norm (and I have the impression that most pro riders are shorter than I am as well) it just makes me wonder.

What felt bad on the 180, or what feels better on the 175? I haven't had a setup to swap the different lengths on the same bike just yet.

I had some 165s and 170s and was fine ... but I had 175s on one bike and while I could barely feel any difference after the first minute ..... overall I Felt (no reason, no measurement) better with the 175s. So Now I have 175s on five of my six road bikes and I love it.

I cannot tell you if I spin faster or generate more torque or anything .... but I know some portion of my brain says "yes" more loudly on the longer cranks. I forget my cycling inseam, but I am a little over six feet and have ridiculously long legs for my height. I realize none of this really helps, sorry ...

But it is a lot more than height. leg strength, hip flexibility, lung and cardio capacity, slow to fast-twitch muscle proportions. ... all kinds of physiological uniquenesses determine what fits each of us best.

I say, get a set of 180s and see.Shop Ebay for used or take-offs or whatever, maybe .... if nothing else you can throw them back on EBay for a minimal hit and have important data.

Sometimes I feel like im the only person running 165

I am sure there is a support group somewhere .....

I run 165s as well.

that wasnt supposed to be as sad as it sounded haha

The part (virtually) no bike company takes into account is BB drop. Most bikes, whether it's a 47cm or a 62cm, same BB drop-- but they'll put every crank length on there. Which means right off the bat, my pedal is 10mm closer to the ground than my wife's (hers 165mm, mine 175mm.) We tall(er) folks don't like pedal strike either. It's test-ridden her bike, looking much like a circus bear. I don't think I could do 165s. It's only a 10mm difference, but they felt really short.

I am 6'5 and use 170 or 175mm cranks.
don't remember my cycling inseam, 37" or something like that, maybe a bit more.

170mm cranks on all my c&v road bikes. 175mm cranks on my 2 modern road bikes.

I dont want anything longer...i haven't been riding and wished for longer crank arms. I haven't though 'oh man, some 185mm arms would make this fun!'

Adam Hansen uses 180mm cranks; I believe he's 6'1". FWIW.

It won't hurt to at least try them.