Greetings all,

I have a Centurion Ironman Expert that was formerly outfitted with Suntour GPX components and am trying to upgrade to 7 Speed Sora STI with 105 derailleurs. Since the bike has been in storage for a while I am trying to remember if the bike was originally a 6 speed setup.

I threaded on a 7 speed Sachs Maillard freewheel on the Bullseye rear freehub and installed the Sora STI levers, 105 derailleurs, and a SRAM PC 58 chain.

After adjusting the derailleurs the bike shifts like a dream with little or no noise in all gears except the 13 tooth smallest cog of the freewheel. When I am in the smallest cog the chain rubs against the frame near the vicinity of the cog. It doesn't look like there is sufficient clearance to accomodate the chain and 13 tooth rear cog. In other words, the cog looks to be too close to the dropout.

If I am correct, even if the bike originally used 6 instead of 7 speeds, the spacing should be 126mm and should work for either. I have also read about the possibility of re-dishing the wheel to accomodate a possibly wider freewheel. Again I don't remember if the original freewheel was 6 or 7 speed so I don't know if this is necessary. Also, wouldn't re-dishing the wheel do nothing to move the cog further away from the dropout?

I have thought about adding a washer to the outside of the axle to increase the spacing from the cog to the dropout and it looks like it may correct the rubbing problem. If add this washer will all I have to do is readjust the derailleurs to accomodate the new alignment?
I know this is a long post but I am really scratching my head here. Thanks for any and all help with this.

Rich