As I noted earlier, when I replaced the old 52-42-26 chainrings I ordered smaller ones: 48-38-24. That was when I supposed the new rear wheel would use my existing 11-30 cassette.
Well, come to find out, the BionX hub only supports the old-fashioned thread-on freewheel, and not the modern (since, like, 1980) freehub and cassette. This is a major shortcoming in an otherwise well-engineered system. I cannot fathom why they would not have designed the motor/hub as a freehub accepting a cassette.
There is a very limited choice of 8-speed freewheels; in fact, the authoritative Sheldon Brown site advises against even using them. Certainly there are none that have an 11-tooth high gear.
In fact, Joe stocked only a 14-32 freewheel, and that's what was installed. This reduced the top gear an additional 20% for a total reduction of something like a third in the available top speed.
The result is that now I'm spending all my time in the big ring, and I cannot pedal faster than about 27mph—on a downhill where before I could pedal to 35.
The 24-tooth inner ring is just useless, I haven't even tried it. The middle ring is good from about 8 to 20mph, and with the electric assist, I can't imagine a hill that would need the granny.
So far as I can see the only cure is to buy three new chainrings, at least the old 52-42-26 sizes, and perhaps larger. Which will be a bit of an expense. Sigh.
Update: A correspondent at the Easy Racers forum pointed me to comcycleusa.com where they do stock 8-speed freewheels with 11-32 gearing. I ordered one instantly and will post when it arrives.
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