The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: rocker21 on 14.01. 2022 11:27
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fitted a belt drive to my A7ss and i like it, but the gearing is a bit high, does anyone know if a bigger rear sprocket is available, standard is 42 t i recon i need something like a 45.
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Depends on the year of the bike. If you have 1954/55 and use the Gold Star type rear end there's a 46 tooth available. Full width hub ones only have a 42 tooth option to the best of my knowledge. If you've got an old sprocket you could get a firm like 'Talon' to re-tooth it with the number of teeth you want. Other than that you're looking at altering your gearing with the gearbox output sprocket which is a bit of a PITA. However, you should only need to do it once if you can calculate the teeth you want.
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its a 1960 A7ss with the cast hubs, and a bob newby belt drive conversion for the primary drive, its very smooth but they only make the one size engine pulley which is for the A10 and its a bit high geared in top, so looking for suggestions on how to lower the gearing a bit, would prefer to change the rear sprocket, dont care about the spedo drive as i am not using that, got a gps spedo fitted.
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I use Bob Newby belts on my bikes and really like them. The options I described above are all that's available to the best of my knowledge. I think you should go down a tooth on the gearbox sprocket.
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G'day rocker.
I think I mentioned in another topic that I re-toothed my rear sprocket in a few different numbers of teeth. Similar to CB's suggestion.
First turned all the teeth off the old sprocket then turned the center out of an alloy sprocket to match and used 6 bolts as scotch keys to hold together.
You could use steel and tack weld in a few spots.
Cheers
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Neat job!