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small circles or more leverage ?(6 posts)

small circles or more leverage ?eayste
Aug 14, 2003 5:29 PM
I recently purchased a new Road bike.
I have had it about a month and have put about 300 miles on it.
While wiping it down the other day and I noticed it had 172.5mm length crankarms on it .
All the other bikes I have or have owned all had 175mm length crankarms on them.
Both my singlespeed mtn bike and my Full suspension mtn bikes have 175mm arms on them.
The only noticeable difference with the crankarms I have noticed is , with my style of climbing , is to spin up 80% of the hill then shift into a harder gear and stand.
That when I do this I do not have the leverage I am use to with the 175mm.
Now I know it's only 2.5mm or 5mm on the entire rotation.
But I was wondering if anyone else has expirience with different crankarm lengths on different bikes.
Does it mess up your spin or riding style ?
I am considering selling these an getting 175mm arms to make all my bikes the same.
So my pedal stroke stays consistant.
Or Should I keep the 172.5's on one bike and spin more ?
Any comments or suggestions are appreciated.
Depends on your pedalling style & height...Synchronicity
Aug 14, 2003 9:45 PM
I have only ever used 175mm cranks, as that is what my first bike came with. I suspect a lot of people out there are like me: it is too hard/$$ to experiment so they stick with what they know.
What I have heard is that you should use bigger cranks if you have longer legs/femurs. Since I am 5'11", I think 175mm cranks suit me OK, so I was confident enough to order a set of record carbon cranks in that size without even having tried any other size!! If uou are shorter, say 5'9" then you may want to stick with the new 172.5mm cranks.

There is still no definitive answer on crank length. Look how that powerhouse Jan Ullrich pedals (slow cadence) compared with Lance. They are both effective ways of pedalling (he almost dances on those pedals). And for all you Americans that think light shines out of Armstong's butt, you may want to recall that Jan Ullrich absolutely hammered Lancey-boy on one of the time-trial stages (aka the race of *truth*) by WELL over a minute! Why didn't Jan win then? Perhaps Lance has a better overall team.
he he he.
Depends on your pedalling style & height...eayste
Aug 14, 2003 10:05 PM
Well , I am more like Ullrich . I'm 5'10" with a 33 inch inseam and usually have a slower cadence in a bigger gear.
But I have recently discovered that spinning in a lower gear is easier on my knees than pushing a big gear .
While my climbing stays about the same but is slightly better with the 175 when out of the saddle over short distances.
The 172.5 length is new to me since I also have used 175's for nearly 10 years.
I just needed a different perspective.
I can't tell any difference.dzrider
Aug 15, 2003 4:50 AM
I've had 170,172.5 and 175 and after a few minutes I can't tell. The difference in leverage between 175 and 172.5 is 1.4%. Did you notice it before you saw the numbers?
Aug 15, 2003 11:38 AM
I could kinda feel the difference.
I noticed that I was able to spin faster and effectivly climb better in the saddle.
And with about 50 ft to the top of a climb when I usually stand up . I noticed a little lack of power.
I also noticed that the ever common twinge in my knee that was slightly irritating was almost gone.
Since you have to pedal a 5mm smaller diameter circle.
My knee doesn't move as much through the rotation of the
So there is a little difference.
Find out what your own legs like. . .Mike P
Aug 15, 2003 6:30 AM
I had one bike with 175's. It was my first road bike and at the time I was fine with the crank arm length. Along came my next road bike, it had 172.5. I did not notice any difference I could attribute directly to the change in crank arm length but my cadence did increase a bit.

Somewhere, sometime, I read and heard higher cadence and shorter crank arm length bs and changed over to 170mm. I was able to spin faster on the 170's than the 172.5 or 175 but did not feel as "strong" on the hills or when I was pushing my pace. After 6 months or so on the 170's I went back to the 172.5's, which is what I've been using since.