Sram Red chainset rotates out of true.

chris1001
chris1001 Posts: 58
edited March 2012 in Workshop
...Not quite a wobble, more like both chainrings are warped, and did this from new. If spinning the cranks I can measure about 1.5mm of lateral movement on the outside edge of the larger chainring, like the ring is tilted. First thought was that the BB might have been badly machined (this was also new), so as an experiment I removed the Sram chainset and BB and installed an Ultegra chainset with Shimano BB. This setup is much better and seems to be less than 0.5mm out of true. I then loosly installed the Sram chainset into the Shimano BB, and spun it up, suprisingly the amount of deflection on the dial gauge had reduced to almost the same as the Ultegra chainset.

Next I swapped out the Sram BB, reinstalled the chainset and span it up without torquing everything up, it span up fine, hardly any play. Tighened the BB cups and the left crank arm retaining bolt and hey presto its well out of true again. Took the chainrings off and checked them for flatness on a glass table - they are fine.

I'm wondering if the carbon spider might be distoring when the whole lot is pulled together as the left arm bolt is tightened....? Done some searching on Google but cant find anyone else moaning about this. Frame is a new Planet X Nanolight Guru.

Expert advice welcome please, cant really afford to buy another Red chainset just to try out my theory.

Cheers!

Comments

  • sandyballs
    sandyballs Posts: 577
    Had a problem recently with the SRAM Red cassette becoming unbonded, when I spoke to the SRAM technical helpline, they said RED has a 2 year guarantee and i should return it to point of sale with receipt. If you bought it new recently you should try to return it. I bought mine from Fudge amd so far have no troubles.

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