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Should I go for the 175mm cranks?(5 posts)

Should I go for the 175mm cranks?jzinckgra
Jul 3, 2003 2:44 PM
I've been using 172.5mm cranks (FSA) for the last 4 years and am getting another pair and have the choice of either 172.5 or 175. Since I'm so used to the 172.5, I'm wondering if I should even risk going any longer. Is there really anything to ge gained by going longer? I've heard that a longer crank arm gives you more leverage. But wouldn't they also slow your high speed spins down? I'm more of a spinner, especially on the hills. BTW, I'm 6'2" with a 33inch inseam. Thanks.
re: Should I go for the 175mm cranks?GTIronman
Jul 3, 2003 4:31 PM
I'm only 5'9" with a 30" inseam. I recently tried 180's for 6 months. I was significantly faster, but I started to notice some irritation in my hip flexors and front of knee (below knee cap). I just went to 175's and the discomfort went away. I'm not as strong in the mountains, but I'm not hurting myself. I suggest that you try something between 175 and 180 and see how you do. You'll like the longer cranks.
"I was significantly faster" ??filtersweep
Jul 4, 2003 1:49 PM
No offense, but I find that hard to believe- or it was all in your head... SIGNIFICANTLY?? If that were generally the case, we'd all be on bigger cranks.

I had been riding a 175 for years, and ordered one when I had my newest bike built. A year later while cleaning it I noticed that it had a 172.5! I hadn't even noticed. THAT is how significant a 2.5mm difference can be.
No predicting effect of crank lengthKerry Irons
Jul 3, 2003 5:49 PM
The general rule is that longer cranks means lower cadence, but beyond that there's no studies that definitively support any conclusions about crank length. Better phrased, there are lots of studies, but since they tend to disagree with each other, one must conclude that this issue cannot be defined. The human body is very adaptable, and there is a wide variation from person to person, and these factors seem to swamp out any measureable differences in crank length. Some people claim great impact from small changes in crank length, while others can't tell any difference (or no significant effect).
re: Should I go for the 175mm cranks?morency
Jul 4, 2003 10:27 PM
normally a high speed spinner (above 90 rpm average) has no advantage with a longer crankarm, only on heavy hillclimbs with a drop of your rpm, you will be able to go a tiny bit faster due to the bigger leverage; it will slow your high speed spins down (you are making bigger circles)
Johan Museeuw uses a 175mm (he's about your size)
Axel Merckx uses a 180mm (he's a couple of inches bigger than you)
they both have low rpm
almost everybody else uses a 172.5mm (to my knowing)