Correct chainline is important to minimising chain rub. Short chainstays exacerbate the problem of chain rub on the large chainring... With longer chainstays the problem will not exist - so movingn the wheel back in the dropouts might help. However you certainly should not use the small to small or large to large combinations.
Hilary Stone, Bristol, British Isles
John Clay wrote:
> I have discovered that when on the small ring and smallest two cogs the chain rubs the inside surface of the large ring. It's a Stronglight 99, 48/28 with shortest BB spindle projection on right side possible. Is that a known issue with wide range double arrangements? I haven't calculated the geometry (will undoubtedly do so), and I know that on this particular frame I skewed the BB alignment a skosh, in a direction that would exacerbate this issue (fortunately I know why). Still, I wonder if this is part and parcel of such a large difference in the diameters of the two rings. Anyone?
>
> John Clay
> Tallahassee, Florida
> USA
>
> http://healthcarefunding.blogspot.com/
> Single Payer IS the compromise.