Replacement Crank Arm

doilum
doilum Posts: 12
edited October 2014 in Workshop
My friend has a Planet X Carbon Pro with the SRAM Rival groupset (I think 2012). He has managed to bugger the threads whilst installing his toe clip pedals (yes I know :shock: ) on the left crank arm. I am looking for the replacement for him as the bike shop told him it'll need the whole crank set replacing and I think they're having his pants down.

Question is which is the right one to get. I know the length is 175mm but the crank arm doesn't have SRAM Rival on it like the replacement ones do and the part numbers on the back don't tally up either, nor can I see the part number in the parts catalogue! I'm guessing that although the bike is equipped with Rival the crankset may not be but will a replacement Rival crankarm fit?

Comments

  • keezx
    keezx Posts: 1,322
    edited October 2014
    http://www.evanscycles.com/products/sra ... m-ec045655
    http://www.evanscycles.com/products/sra ... m-ec045654

    Almost any crankset has a brand name somewhere on it.
  • Pokerface
    Pokerface Posts: 7,960
    A photo would go a long way to answering your question. There is no way to answer it correctly unless we know what exactly IS on the bike. It could be Rival, another SRAM product, it could be Shimano or FSA, etc, etc.

    Or do a google search for the part number and see exactly what comes up. That might tell you what it really is.
  • doilum
    doilum Posts: 12
    Keezx wrote:
    http://www.evanscycles.com/products/sram/rival-left-hand-gxp-crank-arm-ec045655
    http://www.evanscycles.com/products/sra ... m-ec045654

    Almost any crankset has a brand name somewhere on it.

    It just has SRAM on it and is mirror black finish. That's what made me think it was perhaps S100/150 crankset or something like that and got me wondering if it particularly mattered getting the Rival as a replacement.
  • Pokerface
    Pokerface Posts: 7,960
    Sounds like S500.

    Check this document: https://sram-cdn-pull-zone-gsdesign.net ... _rev_b.pdf

    It has all the part numbers for SRAM replacement parts. You should be able to find your mate's part number in there. Page 21.
  • lesfirth
    lesfirth Posts: 1,382
    A good LBS can repair it by fitting a helicoil insert. Cost is less than £20.
  • Pokerface
    Pokerface Posts: 7,960
    lesfirth wrote:
    A good LBS can repair it by fitting a helicoil insert. Cost is less than £20.

    True. But it takes a VERY good LBS.
  • keezx
    keezx Posts: 1,322
    lesfirth wrote:
    A good LBS can repair it by fitting a helicoil insert. Cost is less than £20.

    A new Apex cost 40, would never mess with helicoils for 20 less.
    Apex and S500 are the same.
  • Monty Dog
    Monty Dog Posts: 20,614
    Keezx wrote:
    would never mess with helicoils for 20 less.
    Apex and S500 are the same.

    SRAM lower-end cranks are made from cheese - a helicoil will be stronger.
    Make mine an Italian, with Campagnolo on the side..
  • keezx
    keezx Posts: 1,322
    But the helicoil is also in cheese, so what's the profit?
  • desweller
    desweller Posts: 5,175
    Keezx wrote:
    But the helicoil is also in cheese, so what's the profit?

    the helicoil is a bigger diameter external thread and the material is usually more suitable for a screw so it will be able to support more torque.
    - - - - - - - - - -
    On Strava.{/url}
  • keezx
    keezx Posts: 1,322
    A helicoil in a cheap crankarm is Murpy's law IMO.
    Just asking for more trouble.
    An expensive cylinderhead is a different story though.
  • desweller
    desweller Posts: 5,175
    Keezx wrote:
    A helicoil in a cheap crankarm is Murpy's law IMO.
    Just asking for more trouble.
    An expensive cylinderhead is a different story though.

    the engineering principle does not change from one application to the other. the larger diameter thread can support more torque and is made of a harder material.

    have you actually had a helicoil yield in a crankarm? I wager not.
    - - - - - - - - - -
    On Strava.{/url}
  • keezx
    keezx Posts: 1,322
    No , I'm aware of Murphy's law.....

    Take a look at the pedal eye of an Apex crankarm and how "much" material is present there to take the loads.
    Plain stupid , sorry....
  • Monty Dog
    Monty Dog Posts: 20,614
    Given the option between a replacement SRAM crank and a helicoiled one, the helicoil will be stronger and less likely to strip-out
    Make mine an Italian, with Campagnolo on the side..

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