Wonky chainset

tripwire Posts: 505
edited September 2009 in Workshop
I just installed a new stronglight speedlight triple chainset and on spinning the cranks I noticed that all the chainrings were moving side-to-side as they turned. It's worst on the big ring, which moves in and out by about 1-2mm on each rotation.

I reinstalled it on the spindle at 90 degrees to the original orientation to see if the BB spindle was at fault, but the same point on the chainrings ended up closest to the frame.

Is that amount of... erm... wobbliness... normal or shouild I be worried about this?


  • Monty Dog
    Monty Dog Posts: 20,614
    If you're positive that the cranks are fitted squarely to the BB, isn't disorted and it doesn't loosen in use then it's probably down to a distorted spider - probably a consequence of shrinkage in manufacture. Take the cranks off, remove the chainring and lie it on a flat surface to see where the distortion is - 1-2 mm 'wobble' should be tolerable, but it means you'll have to set up the front mech accordingly. Depending on the design of chainset, you can sometimes 'tweak' them back into position using a large adjustable spanner - carefully as aluminium doesn't like being 'worked' too much or it will simply crack. If in doubt, take it back.
    Make mine an Italian, with Campagnolo on the side..
  • Thanks,

    I'm sure I have them installed squarely and the BB isn't wonky. Since they're on now, I think I'll fit the rest of the drivetrain and see how it goes. If it ends up causing problems I'll break out the adjustable spanner... if it's good enough for Sheldon it's good enough for me ;)