Warped Chainring or Ramping Surface?

sc999cs
sc999cs Posts: 596
edited June 2008 in MTB workshop & tech
My bike has a Truvatic Firex chainset. I had a really bad creaking noise which always occurred at the same point on the pedals' rotation - left crank pointing forward and horizontal. I've tracked this down to the middle chain ring. It has a major 'warp' at 180 degrees to the crank arm (about 3 or 4mm out of true). This was causing the creak as the chain rubbed the front derailleur on that part of the cranks' rotation.

Do I have a faulty chain ring (unlikely I'd hope due to SRAM quality control) or is this possibly a ramping surface to help with gear changes? Any other owners able to confirm?

Regards

Steve C
Steve C

Comments

  • nicklouse
    nicklouse Posts: 50,673
    the ring should not have any deformation in it. make sure the bolts are tight.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • irony
    irony Posts: 43
    The actual teeth of the chainring should all be in the same plane.
    2750921120_2950536dcb_s.jpg
  • sc999cs
    sc999cs Posts: 596
    Looks like I've got a bad ring then. With the chain on the smallest socket it is almost touching the middle chain ring by the warped section while the rest has a good few mm of clear space. Question is who deals with the warranty on this..?
    Steve C

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