Bought Used bike- possible chainset change

kaveh
kaveh Posts: 10
edited April 2017 in Workshop
Hi everyone,

I bought 2015 SIRRUS COMP CARBON DISC yesterday. The crank got lose half way so i thought it was simply a lose nut.

Came home and unscrewed the left arm and found damage to the bearing.

Does this mean I have to change the whole chainset?

According to the site the chainset is : FSA Gossamer, forged alloy, compact

http://www.specializedconceptstore.co.u ... rbon-disc/


The length is 175mm. How can I find out about other specs? Any chance I can replace the arm only as the bottom brakes seems to be fine after checking.

They broke my Kryto lock and stole my bike last week. Seems i haven't got much luck these days.

The part seems to be the most expensive component. Thanks for all your help. quite new with crankset specs.

Thank you

images

2f08sva.jpg

1zbds0w.jpg

Comments

  • trailflow
    trailflow Posts: 1,311
    If the splines on the right arm spindle are also damaged. Then you need to replace both arms.

    You can replace the crankset only and keep the bottom bracket (its either a pressfit MegaExo, or screw in threaded MegaExo cups). If you do, you need to replace the crank with the same type a FSA MegaExo road crankset.

    If you buy a Shimano crankset. You would need to replace the bottom bracket with a Shimano 24mm compatible bb.
    If the frame requires a threaded bb, they are alot easier to remove and reinstall compared to a pressfit.

    Are you sure the damage wasn't caused by the previous owner ? How far did you ride the bike ?
  • kaveh
    kaveh Posts: 10
    Thank you for all the info. I know a lot more about chainset than before!

    I did around 15 miles. all the 3 bolts on the left hand side were lose. I tighten it up and it seems fine. no more missing but the arm is surely damaged and if it gets lose again, I was told that i need to change the arm. The BB is ok. They seems to be very tough!

    Now I will see if i can order the arm from FST.
  • svetty
    svetty Posts: 1,904
    That looks like a Shimano hollowtech crank not an FSA??
    FFS! Harden up and grow a pair :D
  • keezx
    keezx Posts: 1,322
    kaveh wrote:

    Now I will see if i can order the arm from FST.

    No , you can't , and neither from anybody else, because it's a Shimano arm.
  • trailflow
    trailflow Posts: 1,311
    It's an FSA MegaExo crank.

    The splines on a Shimano Hollowtech II crank are not as deep and there are lots more notches.

    Shimano
    IMG_1109a.jpg

    FSA MegaExo on the right (ignore the green and red text)
    fsabolts.jpg
  • kaveh
    kaveh Posts: 10
    It is FSA. Thank you for the info. I just tightened it up and it's not lose yet. If it get lose, I will have change the whole crankset. FSA is not manufacturing the arm anymore.
  • de_sisti
    de_sisti Posts: 1,283
    If you bought it form a shop can you get them to sort it out for you? They shouldn't have sold you faulty goods.

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