Chainring Problem

MabBee Posts: 40
edited December 2008 in Workshop
The large chainring on my R700 chainset (ie effectively a Shimano Ultegra Compact chainset with 50/34 teeth) wore out really quickly. I have swapped it for a TA chainring with the same number of teeth -- the TA chainrings are better value and supposedly last a lot longer. However, I now find that when I'm using the granny ring, the smallest four rear sprockets are not useable -- the chain rubs badly on the inside of the new large chainring when I'm in these ratios.

Comparing the shimano chainring that I took off, with the new TA chainring, I can see that the shimano chainring is tapered towards the outside, meaning there is more space for the cahin to run next to it on the granny ring: so the rubbing prob;em is aopided/

Are there fixes to this problem? In days of old one would have used a BB with an extra 2mm in axle length -- of course this is not possivle with Hollowtech II. I've thought about putting spacer washers between the new chinring and the crank spider -- but that could just provide a gap into which the chain will fall and jam.

I really don't want to go back to SHimano chainrings, 'cause they wear out too quickly.


  • John.T
    John.T Posts: 3,698
    You can put a spacer behind the drive side BB cup. The one used behind a single speed, fixed cog or screw-on cassette will fit. It will afect chain line though. Washer behind the ring would probably be better. The TA ring has probably closed the gap up anyway.
    The joys of mix and matching.
  • John C.
    John C. Posts: 2,113
    Seem to remember a club mate cursing shimano for the same reason, He said TA were not compatable because they were not dished like the Shimano ones.

    Fail to prepare, prepare to fail
    Hills are just a matter of pace