Originally Posted by
DorkDisk
To fit 9 cogs on a 7sp Shimano freehub, one can remove the freehub and install a 8+ sp freehub. The easiest way to do this is to get a complete donor rear Shimano hub and transplant the entire axle, drive side bearings and cones, and freehub.
This is important as you want to use the correct cone and DS seals changed in diameter throughout the 90’s.
I believe the HG-50 freehub body has a thin flange. It would be best to find and 8-10 speed one with a thin flange. If you don’t it will make the DS even wider. Regardless of what 8-10 freehub body you use, you will need to re-dish the wheel to center it in the frame. The less you need to re-dish the better chance you have to not run out of spoke/nipple threads.
John