SoCalAl

I was wondering what the down side is in using 175 cranks in place of 172.5's other than a decreased lean angle. I live in an area with a lot of hills and thought that going to a longer crank might help in climbing (?). Just a thought.

BryE

It will make your cadence a bit slower, and your knees will have a greater bend when the pedal is at the top, meaning less power at the top of your stroke. You'll also have to lower your seat to match the new height of your foot at the bottom of your stroke. Of course, this is only 2.5 mm, which is a very small length - if you're not a very experienced rider, you may not even notice the difference.

I've heard you can determine your optimum crank length through the following formula: find the height of the top of your femur when standing, and multiply that length by .185 (that is, 18.5%). You can find the top of your femur by lifting your knee when standing - you will feel your femur move backwards. It's 4-5 inches below your pelvis on the outside of your hip. Of course, this is only a general rule; there is no substitute for actually using the crank and seeing how it feels.

ggg300

https://www.bikeforums.net/showthread...t=Crank+Length

let us know how it goes...

MichaelW

Using the same pedalling force, a longer crank is turned more slowly at a higher gear ratio. Some people prefer them.
"long" is a relative term. A long crank for one rider may a a short crank for a larger rider. Check out what your "normal" size crank is first, in proportion to your leg(/femur) length.

woodboy

You'll risk offending the seat post police when you lower your seat to reach the bottm of your pedal stroke.

biker7

Increasing crank length...like every other subject on this board is highly contentious...lol. I am going the opposite direction...going from 175 to 172.5mm cranks in about a week or so...when I get a chance to pull the cranks. Is it a big deal? no. Will you feel it?...would say most would...I know I will enjoy the marginally shorter cranks because I like to spin. I have a 35.25 inch cycling inseam or am pretty long legged. Crank calculators put me on 180mm cranks. I don't like even the length of 175mm cranks but find them beneficial in the big hills. Another data point to extrapolate from is what the best riders in the world ride...the guys who raced in this year's tour. These are guys that are going for maximum speed and are the best conditioned athelete's on the planet...or close to it. A board member recently published a list of crank lengths for cycling stars. Many if not most race on suprisingly pedestrian length cranks... many in the 175 and even 172.5mm range...and these guys...though not necessarily big guys...are willing to sacrifice some comfort for speed. This helps in my decision to error on the short side which is reinforced by testing each. I grew up on 170mm cranks and like them about the best for overall riding...flats and hills. It is very much personal preference...almost like bike fit in terms of how bent over you prefer to ride. Even though perhaps a bit expensive...though not really if you can turn a wrench and with shuffling good components back through E-bay which I do frequently...I believe trial and error is the best tell for what crank length you prefer...and gearing...and frame size...OK I'll stop.
George

Gustav

I had 172.5 cranks on my bike, then I bought a second bike that had 175's. After riding them both last season (for me, about 2,000 miles), I bought a 175 crank for the original bike -- so now they're both 175's. I found that I prefer the "longer" cranks, and could clearly feel a difference. I didn't see much of a difference in my cadence, but I did feel as though I could climb more efficiently. My legs just felt more comfortable and my endurance seemed to improve a bit.

I don't believe there's a right answer for everyone about crank length. I think it's a very individual thing having to do with body size and proportions and riding style.