cpsqlrwn

What crank arm length do you ride, and to make this a little more meaningful, could you also state your height and your inseam length.......

20grit

175mm feels best to me. I'm between 6'-2" and 6'-3" and have roughly (not measured lately, too many other things in life have pushed the actual number aside in my memory) a 34" inseam. I'm mostly torso and not legs.

KonAaron Snake 

170mm

Hair under 5'10

I don't remember off hand...I think 31 inches or so.

cratz2

I have 172.5s on both of my road bikes. I'm 5'7" and have an inseam of just over 30".

I've definitely thought about trying a set of 170s on my 90 Le Tour which is my grab-and-go bike.

squirtdad

175 6' 32 inch inseam (at least for the pants I wear)

02Pilot

I selected 175, as it feels best, though I also have bikes with 170s that I can ride with no detrimental effects. I'm 6'0" with a 34" inseam - long legs.

4Rings6Stars

170 or 172.5 on the road/cross bikes. I don't notice a difference. I've also ridden 175 with no ill effect...

5'8"

Cycling inseam (perineum to floor, barefoot): 29.5"

Novakane 

Never measured my cranks before, I just use what's on the bike and in decent shape...
Turns out both my bikes I usually ride have 170mm cranks and they feel just fine when I ride. I'm 5' 11" tall with approximately a 32.5" inseam from a quick measurement.

divineAndbright

175s, I tried out 177.5s and like em too but im afraid of pedal strike at that point. I can live with 172.5 if I have too, but wont use anything shorter.

bradtx

6' and 32.5" inseam and presently using 170 mm cranks. Most of my bikes had 172.5 mm crank arms and my dedicated distance roadie had 175 mm crank arms. Crank arm length is easily adapted to, IMHO.

Brad

ColonelJLloyd 

I think my PBH is 91cm and I ride ~62cm traditional (level top tube) frames. I have a touring bike with 175mm arms, a go-fast bike with 172.5mm arms and the rest of my fleet has 170mm arms.

We humans can adapt well, but I recently rode 116 miles on 160mm arms and I'm certain that they are not for me and my riding style.

byhsu

5'9" with about 32" inseam, i use 172.5mm cranks arms.

AZORCH

I've got bikes with 170, 171, 172.5, and 175 crank lengths. If I've been riding 175s for a while, then I'll notice a difference if I jump on a bike with 170s - but only for a little while. So long as I have the saddle height adjusted correctly, there's little meaningful difference for my riding. This is a topic I did quite a lot of personal research pursuing several months ago, so I don't want this to seem like an off-the-cuff response to your question. For me, I found a much greater and more noticeable difference when I compared different Q-factors - distinct enough to me that I actually found it startling.

For the record, I'm 6' 1 1/2" and my trouser inseam is 32 inches - but trouser inseam is nearly meaningless; you most likely want pubic bone to floor measurement. More to the point, however, is top-of-saddle to center-of-crank distance; that measurement is 78.25 cm. That measurement changes slightly for different pedals, btw. SpeedPlays meet the bottom of the shoe differently than SPD or toe clips, for instance, and that can affect fit.

clasher

I have 170s on most of my rides, I tried 165 and didn't really notice a difference. I ride in thick soled sandals a lot but also really thick soles... the difference in thickness of the soles is more than 2cm I'd reckon. I couldn't likely tell the difference if I was blind-folded on my bikes. I'm 180cm and I can't remember my inseam or where any of my many tape measures are, so I can't tell you

repechage

The optimal crank length is not just inseam. Femur length and shoe size, and actually foot length in front of your ankle joint are as important. Also, flexibility or lack thereof also play a role. Not too mention the style of rider you are, spinner or cranker. I am leaving out if the saddle height is correct, more often wrong than right.

strock 

170mm on road/touring, 175 on MTB. Height is 5'8'. Pants inseam is 30 inches; not sure about bike inseam. I prefer the feel of the 170s.

cpsqlrwn

All of what you say is true. It's a lot more complicated that height and inseam, but I chose the path of the most meaningful data that most people would know offhand with least amount of input on the part of the poster.

mikemowbz

175mm seems like a sweet spot to me, relative to shorter options. While I'm not completely sure it's not all in my head, I do find my trusty Nishiki, with its 175mm modern Shimano cranks, a little better in that specific regard than my current one-and-only while away from home, a Marinoni which sports a 170mm tricolor set (the dimensions of the two bikes are otherwise very similar, ~62cm ctc, and I feel like my legs are looking for that extra crank length sometimes these days). ~60-63cm frames are generally my thing, and I've ridden 170mm, 172.5 and 175.

6'2 1/2", 34.5-35ish inseam (based on memory of my own incompetent measurement attempts). I tend to mash (i.e. pound the pedals), though I can see some of the appeal of a moderately shorter crank for spinning at a nice regular cadence.

In fact, though, I've been seeking a 177.5 or 180mm crankset to experiment in the other direction...and with which to practice my pedal technique (or die trying).

iab

170, 172.5 and 175. 72" , 32"

I can't tell the difference between them.

rootboy 

How long is my crank? How dare you.



(six foot. 32. 170 mm)

repechage

True, so if the inquiry is flawed, what is the worth of flawed data?

Why have most accepted the Kool-Aid of 175 length cranks on a mtb?

teetime

The better question may be 'what is the intended use for a particular crank length?'

I have bikes in 170, 172.5, and one in 175. Given my style riding I prefer a 172.5. Like iab, I can't tell the difference in normal riding. In sprints or climbs, I can. I spin more than mash. All my bikes have nearly identical contact points. A large change in crank arm length will most likely have an effect on KOPS, if you size by that method. In any case, the fore/aft of the saddle may have to change from 'normal', depending on the ST angle...

No set answer to that question, too many variables.

Are you trying to fit your new Primato? If so, it has a laid back seat tube, you may have to go shorter cranks, forward saddle position, and a shorter stem. Not ideal, but may work, fit-wise. Take a bike that is comfortable, and try to match contact points. I'm assuming you are not a kid, and maybe not as limber as you once were. Comfort on a bike is foremost. Duplicate what you know works, and make small changes from there, after your body tells you to.

Most of my bikes have the same saddle/bar setup, so it's easy to make some simple measurements. With different bars and saddles, it would get more complicated. I strive for center of BB to top of saddle, tip of saddle to center of stem, and handlebar drop/hood position as close as I can get.

Contact points, to reiterate.

whatwolf

170, 172.5. I think I prefer the longer ones. 5'7", 32", long femurs.

cpsqlrwn

There is a big difference between flawed and incomplete. I chose to keep things a little simpler, but data that is reported and is accurate is hardly flawed.

cpsqlrwn

Not trying to fit the Primato. I won't have any problem with that. I was told the crank was a 170 which is what I normally ride and it arrived with a beautiful C-Record crank that happens to be 172.5. So I am going to ride it and see how it works for me. I have always ridden 170. I am 5-10 with extremely short legs which, if I understand all these comments, might be pretty meaningless. The most interesting comment I've read was one that referred to shoe thickness. These measurements are so small (2.5mm is only 1/10th of an inch) that if one changed shoes to ones with a slightly thicker sole, you would effectively be shortening the length at the 6 o'clock position and increasing the knee bend and lengthening the arm length at the 12 o'clock position without changing the crankset. Lots and lots of little things in this equation. Far too many for me to calculate and compile. So I am just going to go out and ride and see how it feels from a riding standpoint and from a recovery standpoint (identifying any new aches or pains) afterwards. I started the poll because I was interested statistically in the percentage of people using 170 and 172.5 and what their heights were.