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Crank Lengths and Compact Chainsets

  • 21-07-2013 01:01AM
    #1
    bsb1971
    Registered Users, Registered Users 2 Posts: 575 ✭✭✭


    I've read a lot of the posts on here about crank lengths, and online, but one thing that I haven't come across is crank lengths in relation to compact chainsets. I bought (some time ago on ebay) a Ultegra 6600 compact chainset - recently finally got around to using it on a new bike build only to discover that it is a 175mm chainset. Up till now I have always used 170mm or 172mm cranks on 52-39 chainsets. Will a compact with 175mm cranks generate more power or am I completely off the mark. I suppose what I am really asking in a roundabout way is should I get a compact with 170 or 172.5 cranks instead of the 175s? Thanks in advance for any advice.


Comments

  • #2
    feck sake lads
    Closed Accounts Posts: 2,889 ✭✭✭feck sake lads


    recently enquired about a new frame from sjs cycles in the uk and i also asked, given he size of the frame they recommended 52.5cm, what size crankset should i be buying 170mm was recommended.
    so i reckon if your frame is bigger say 54cm then172.5 might hit the sweet spot.;)


  • #3
    Beasty
    Administrators, Social & Fun Moderators, Sports Moderators, Paid Member Posts: 78,525 Admin ✭✭✭✭✭Beasty


    bsb1971 wrote: »
    Will a compact with 175mm cranks generate more power or am I completely off the mark.
    It's you that generates the power, not the cranks;)

    A longer crank length provides more leverage - basically your leg goes a bit further to generate the same power, in the same way as lowering your gearing slightly will.

    Essentially although there are some standard formulae for estimating the "best" crank length it's down to personal choice. I use a 175mm crank on my road bike and 170mm (previously 165mm) on the track bike. I've lengthened the track bike one because it gives me slightly more leverage when I don't have a gear-change option.


  • #4
    bsb1971
    Registered Users, Registered Users 2 Posts: 575 ✭✭✭bsb1971


    Well every little helps! Thanks for the replies, I was curious (still am!) whether switching to a compact with 175mm cranks would be similar to a normal chainset with 170mm cranks. Reckon I will change the 175 off the bike again, while I haven't used it yet - from all the reading I did last night (what a way to spend a Saturday night lol), I've come to the conclusion that I would be better off with a 170 or 172.5 as I've had some knee trouble in the past.


  • #5
    Lumen
    Registered Users, Registered Users 2 Posts: 30,525 ✭✭✭✭Lumen


    Unless you're running out of gears at either end the crank length is irrelevant.


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