I have a number of wheels which have Shimano compatible 8 to 10 speed freehub bodies. Two of these wheels are intended for use in a time trial bike with 11-speed systems, and one is the new rear wheel bought for the Longstaff tandem (LINK). Accordingly I’ve spent a bit of time figuring out to upgrade these wheels to 11 speed.
Freehubs designed for 8 to 10 speed cassettes are very slightly shorted than those designed for 11 speed cassettes. They can fit standard Shimano cassettes from 7 to 10 speed, requiring a spacer in some cases. You can fit 11 speed cassettes if you drop out one of the cogs. This might not be the best solution for a racing wheel, but works fine if you’re not focussing on smallest cogs.
But you might want to have the full complement of 11 gears. What are the solutions?
1. Mill off about 1.8mm from either the stops on the freehub against which the cassette sits, or off the carrier of the large sprocket cluster of the cassette. This shown in GPLama’s video from a few years ago. The advantage of this approach is that it’s a one time fix. The downsides are that it requires some specialised workshop kit (you might send the freehub or cassette to someone with the appropriate expertise), and it might result in the large cog running unacceptably close to the drive side spokes.
2. EDCO used to sell rather nice (but expensive monoblock steel cassettes, which fit well to 10 speed freehub bodies when used with the specific lock ring with a longer thread. These cassettes are manufactured from a single steel block - none of the cogs are separate. This is a simple but expensive solution that works well for racing wheels. I’ve used these cassettes on a Corima disc wheel and an older Hed 3 trispoke wheel. These cassettes are available from E. Dubied & Co. But this is a pricy solution at £150 a pop! Maybe EDCO is an older name for E. Dubied & Co?
The light and expensive monoblock cassette
3. Finally, Shimano make two 11 speed cassettes that will fit a 10 speed freehub body, the CS-HG800 and CS-HG700 11-34 cassettes. These cassettes fit on a 11 speed freehub body when used with a spacer supplied with the cassette, but without this spacer, the cassette fits easily onto a 10 speed freehub body. This proved an ideal solution for our Longstaff tandem, but rather a wide gear range for road racing.
Above: Shimano's diagram showing how the HG800 cassette uses a spacer to fit on an 11 speed freehub
Above: Shimano's diagram showing how the HG800 cassette fits on a 10 speed freehub - without the spacer