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what are the advantages and disadvanges to using 175 cranks.(4 posts)

what are the advantages and disadvanges to using 175 cranks.fouzilogic
May 9, 2001 9:03 PM
i have a chance to trade my decent 170's for a higher quality pair of 175 cranks..... my frame is 54c and im 5"7'

thanks
re: what are the advantages and disadvanges to using 175 cranks.Jonathan Zook
May 10, 2001 8:39 AM
Having some experience with long cranks (I ride 180mm), there are MANY theories (most are valid) to crank arm sizing. First, and foremost, mathematics dictate that the increased diameter of a circle (your crank arm) will increase the circumference (your pedal revolution). Hence, if you jump from 170mm crank arm length (current revolution distance of 533.8mm) to 175 (pedal revolution distace of 549.5mm) you will notice an immediate difference in your ability to spin. This will have an immediate impact on climbing, sprinting, and low gear riding. For a person with your inseam length (I'm guessing it short since you ride a 54cm frame) I should think most professional mechanics would suggest staying with the 170's, or maybe dropping to a 165mm depending on your riding style. Hope this helps! Happy riding!
re: what are the advantages and disadvanges to using 175 cranks.Alpine
May 10, 2001 10:30 PM
Jonathan touched on some of the main points of this topic and I too think from the info you've furnished that odds are 175s are too long for you ideally. I'm 5'10" and while I could use 175s with no problem, I've always ridden with 172.5s.
Here are a few other things to consider when changing your crank arm length. You might also need to change your seat height and even fore/aft position. A 5mm longer arm will almost guarantee this. Also it would reduce your lean angle for pedaling through turns slightly.

Regards
re: what are the advantages and disadvanges to using 175 cranks.mon t
May 11, 2001 12:07 PM
i am 5-7 also and switched to 175's last year. they feel fine. i ride a mt bike as much as my road bike and i wanted the cranks on each to be the same. i certainly wasn't going to put 170's on the mt bike, so .....anyway i can spin just as fast as before, and climbing is better. the conventional wisdom says they are too long but it simply hasn't shown up yet. i ride a lot and have done so for 20 plus years and i think maybe the conventional wisdom on this issue is a little long in the tooth. go to the velonews tech site for an interesting study on the topic, which, in the end was unconclusive. good luck to you, i think that like me you will be fine with the change, particularly if you also ride a mt bike.