what's length matter?

fred22
fred22 Posts: 509
edited January 2011 in Road buying advice
very nice bloke is selling chainset with 175 cranks. I had a bike fitting at Epic last year and came away with 172.5 cranks. Therefore these cranks are not for me.
When I think about this though the difference is apparently 2.5mm?? Surely I could buy some new road shoes with a slightly thicker sole and encounter a similar difference? So, is this sort of difference in cranks even noticeable?

Comments

  • fleshtuxedo
    fleshtuxedo Posts: 1,853
    You won't notice. If you're riding crits the ground clearance might be an issue, but otherwise go for it.
  • Bobbinogs
    Bobbinogs Posts: 4,841
    Read this...then buy them anyway
  • PieterM
    PieterM Posts: 167
    I have been swapping between bikes fitted with 172.5 and 175 length cranks for over 20 years and still cannot tell the difference when riding....
    European Cycling Trips: http://bikeplustours.com
  • rake
    rake Posts: 3,204
    PieterM wrote:
    I have been swapping between bikes fitted with 172.5 and 175 length cranks for over 20 years and still cannot tell the difference when riding....
    you must have a slapdash pedaling action. :roll:
  • Anonymous
    Anonymous Posts: 79,667
    I can tell when my saddle is a couple of mm too low or high so yes, it does matter...
  • ADIHEAD
    ADIHEAD Posts: 575
    A mate of mine has just ordered some 185mm T&A cranks for an extortionate price :shock: His inseam is 94cm so this seems to back up the BikeDynamic equation. He recently went from Sram Force 175's to Sram Red 177.5's and noticed a huge improvement in smoothness and feels more comfortable as he's been able to lower the saddle. So he's hoping to lower the saddle further still with the 185's, which to be honest he needs to do as he rides the biggest saddle to bar drop I've ever seen!. My inseam is 92cm so I should be riding 177.5' to 180's according to the calculator. Currently I ride 175's on both bikes and can't really justify swapping at the moment, especially as one bike uses BB30 and you can't get anything over 175 without going custom.

    So anyway I personally wouldn't go for 175's unless you are sure they're right for you. One cheap buy can prove an expensive mistake if they're not right for you :wink:
  • ADIHEAD
    ADIHEAD Posts: 575
    A mate of mine has just ordered some 185mm T&A cranks for an extortionate price :shock: His inseam is 94cm so this seems to back up the BikeDynamic equation. He recently went from Sram Force 175's to Sram Red 177.5's and noticed a huge improvement in smoothness and feels more comfortable as he's been able to lower the saddle. So he's hoping to lower the saddle further still with the 185's, which to be honest he needs to do as he rides the biggest saddle to bar drop I've ever seen!. My inseam is 92cm so I should be riding 177.5' to 180's according to the calculator. Currently I ride 175's on both bikes and can't really justify swapping at the moment, especially as one bike uses BB30 and you can't get anything over 175 without going custom.

    So anyway I personally wouldn't go for 175's unless you are sure they're right for you. One cheap buy can prove an expensive mistake if they're not right for you :wink:
  • I know someone who fitted odd length cranks in error - one 175 and the other 172.5 - and he claimed not to notice until a year or so later.
  • ADIHEAD
    ADIHEAD Posts: 575
    I know someone who fitted odd length cranks in error - one 175 and the other 172.5 - and he claimed not to notice until a year or so later.

    Did he notice or did people comment that he'd started walking funny :lol: :?:

    Dunno myself, when I went from 172.50's to 175's it was quite early in my cycling life and my set up was all over the place anyway so I actually didn't notice either to be honest. I suspect now I've got the bike set up right that I would notice, especially if I could get the saddle lower in relation to the bars - I'm 6ft 4 so either have to ride bikes with high headtubes or get a bad neck :roll:

    I think this is the point with getting the right crank length, it allows you to get the bike set up properly. I'm definitely going to look at the possibility of going down the longer crank route for my next bike in a year or two's time. Shame TA only do square taper BB's though, which seems a bit old tech for the money they charge for them :roll:
  • balthazar
    balthazar Posts: 1,565
    I know someone who fitted odd length cranks in error - one 175 and the other 172.5 - and he claimed not to notice until a year or so later.

    That's my experience, as I've reported here before. Only, the difference was doubled– I had a 170 on the left and a 175 on the right. I was a courier at that time, doing heavy miles. I only noticed when I took the cranks off for BB work.

    I'd have put them back, but noticed the right crank was cracked (Deore XT- cracked through the web where many did, due to the poor design which made a stress-raiser there).