Greetings one and all,
Looking for suggestions to raise the gearing on my Ex AA bike which in the past has been uncoulped from its chair.
The engine sprocket is now 21t but that's as much as I know.
Any threads on here or links elsewhere? (not Yahoo BSA&BBe didn't get a bite on there.)

It was suggested I should try here as "The WM20 guys are a breath of fresh air!" the guy said.

Cheers

Lance, I have covered about 700 miles on my engine which I have recently built to M21 spec (600cc and slightly lightened flywheels, cheers Ian) I have used the standard 18T gearbox sprocket and replaced the 19T engine sprocket with 21T. This gives me standard M21 solo gearing, which I find more than adequate.. I think you can go up to 24T engine sprockets. But I'm not sure the engine would pull these unless you live in Norfolk or Holland, where there are no hills. But it's not the end of the earth to experiment, if you don't mind buying sprockets and changing chain lengths. Ron

email (option): ronpier@talk21.com

Thanks Ron,
I will see what gear is on the gearbox then, as with the 21t engine sprocket she only seems happy cruising around the 45mph region.
Bye
Lance

Well mine feels very happy at 50mph cruising. Ron

email (option): ronpier@talk21.com

Hi Lance..If you have an ex WD model you will probably have an 18T gearbox sprocket. A civvy bike will more than likely have a 19T sprocket, particularly if you have a tele fork model.
Either way the 21T engine sprocket would be a good first choice for solo work...Ian

email (option): ian@wright52.plus.com

PS..Niether the M20 or M21 will stand much overgearing..they simply do not have the power to pull it. Performance may be improved on level ground but downward gearchanges will be necessary earlier on the hilly bits. If you have a 19T on the box and a 21T on the engine I wouldn't recommend any more than a maximum of another tooth on the engine sprocket ....Ian

email (option): ian@wright52.plus.com

The bike belonged to the AA from 1957 to 1964 in which time it was tied to a box as they were.
I now need to see what size sprocket is on the gearbox. see you later.