I’ve checked the gear ratios on my Villiers 32a motor and it has standard set (As opposed to the wide ratios), does this mean it’s a road bike gearbox or the standard fitted to trials bikes?

Also I have a 20T primary drive sprocket and a 15T gearbox sprocket, what would be the best size for the rear sprocket?

The difference between a trials box and a road box is the lay shaft gear and the final drive gear ( Output ) Long time since I have one but 27t and 25t rings a bell as I broke a few in my time if the chain came off and locked up braking this gear Primary drive ratio your stuck with I found a sprocket of a125 Villiers but had to make a new key for the crankshaft When I rode Villiers powered bike there was a lot of road work so needed a high top gear

Edited August 21, 201412 yr by naichuff

Yes, I have the 25T - 17T standard gearbox but will this cause me any problems?

And what rear sprocket do I need with the above setup?

Hi you can use this gearbox but to make it usable you will need to change your primary sprocket,a standard one as 20 teeth you will to change this to a 16 tooth and a 56 pitch chain .this should go straight on with out any machining of the gearbox shell to change the centres between the crank shaft and the main shaft.Then the final drive sprockets will need to be 13teeth on the front and 60 teeth for the rear.hope this will help.You can the the parts locally to you at Villiers Services in Quarry Bank .

Hi you can use this gearbox but to make it usable you will need to change your primary sprocket,a standard one as 20 teeth you will to change this to a 16 tooth and a 56 pitch chain .this should go straight on with out any machining of the gearbox shell to change the centres between the crank shaft and the main shaft.Then the final drive sprockets will need to be 13teeth on the front and 60 teeth for the rear.hope this will help.You can the the parts locally to you at Villiers Services in Quarry Bank .

Thank you

Is the 13tooth front sprocket for 428 or 520 chain?

Edited August 21, 201412 yr by suzuki250

Use a 428 chain,if you use a 520 on the smallest sprocket (10t) the chain will ride up on the corners of the nut and it wont run smooth,on some bikes ive ground the corners of the nut to help solve this issue.Also when using 428 chain and sprockets theres a better range of ready made sprockets available,with 520 most sprockets are blanks so you will need to get them machined up to suit your wheel.