Hollowtech II Deore chainset - 170mm or 175mm crank arms ?

hairy_boy Posts: 345
edited June 2010 in MTB buying advice
Well, my truvatix power spline crank arm came a little loose, I thought it was a pedal clicking so have ridden it and now can't get rid of the click even after tightening the crank arm as tight as it will go - pretty sure I have damaged the fit of the crank arm onto the splines on the bottom bracket.

So, looking to get a Deore Hollowtech II chainset.

My current crank arm lengths are 170mm. I ride a 2008 Giant Terrago (small frame size 16" I think) and am 170cm tall, not particularly aggressive or fit :oops:

The 175mm crank arm set can be had for £49.99 but the 170mm length are more - £68ish.

So, the question is, am I likely to notice any difference buying the cheaper 175mm crank version or should I pay the extra and stick with 170mm which I have now ?


  • Torres
    Torres Posts: 1,266
    I'd bet you wouldn't notice a difference at all in a blind test.
    I'd go for the cheaper ones :D
    What We Achieve In Life, Echoes In Eternity
  • Torres wrote:
    I'd bet you wouldn't notice a difference at all in a blind test.
    I'd go for the cheaper ones :D

    +1 to this ^^^^^

    Its generally thought that most people, if any would notice the difference.
  • omegas
    omegas Posts: 970
    Hairy Boy wrote:
    I ride a 2008 Giant Terrago (small frame size 16" I think)

    You will notice the difference if the ground clearance under the bottom bracket is low which you sometimes find on a small frame.

    The reason they are 170mm is to give the pedals a bit more ground clearance.
  • yea... smaller frames usually come with 170mm cranks and larger frames with 175mm.

    Doubt you'd really notice a difference though.
  • blister pus
    blister pus Posts: 5,780
    might have to adjust the saddle height a tad if you've got a regular pedalling efficiency sweet spot
  • 101_North
    101_North Posts: 607
    I recently fitted 175mm cranks to my small frame 2007 Terrago. Perfect for me. Not sure what was originally on there as I didn't check before replacing them but I've not noticed any difference.

  • hairy_boy
    hairy_boy Posts: 345
    Thanks all, looks like the cheaper 175mm chainset it is then :D

    Need to get the frame BB shell faced I think - realistically how much should I expect to pay my LBS to face this for me - I would remove the old chainset and clean the frame so it would literally be the facing ?
  • circa £10 - £20....

    Depends how good your lbs is!
  • blister pus
    blister pus Posts: 5,780
    a lot of bike shops won't actually 'face' the bb unless it really needs it and a lot of modern frames are fine as they are, some aren't though, so depending on what tools the lbs has to get out and what work has to be done will depend on final cost. £10 for fitting a shimano chainset seems standard and £20 if actual big tools have to come out. Like mine started off at 10 but needed the bb re-threading for a specific reason, so ended up 20. but I simply couldn't have done the work myself. they did a great job and it was well worth the money.
  • hairy_boy
    hairy_boy Posts: 345
    LBS, who I have used in the past and have always been good are quoting £17.50 for the facing so seems reasonable.

    Just need to order the BB now and will need a tool for fitting - looknig at this one:

    Anyone got any horror stories on the icetools tool ? any other specialist tools I need for fitting ?