farmer58za Posted October 20, 2013 Report Share Posted October 20, 2013 Hi All I re-built my Cheetah trials bike (37A Villiers motor) a few years ago, but have only now started to use it in classic trials. The bike was put together with whatever came in the boxes and everything fitted as it should. Today, I found the bike was definitely "overgeared". I have established that the final gearing on the bike now, is 15T/54T. Does anyone have an idea what it should be? Thanks in advance David Quote Link to comment Share on other sites More sharing options...
norman_wisdom Posted October 20, 2013 Report Share Posted October 20, 2013 (edited) Hi David, This thread is a good starting point: http://www.trialscen...s-engined-bike/ Edited October 20, 2013 by norman_wisdom 1 Quote Link to comment Share on other sites More sharing options...
villiersprodigy Posted October 20, 2013 Report Share Posted October 20, 2013 Hi David, if your engine as standard gearing (20t primary sprocket)this is what i would suggest.13t front and 60t rear,this is good starting point.Most 32a and 37a engines go ok with this. All the best Anvil Quote Link to comment Share on other sites More sharing options...
farmer58za Posted October 20, 2013 Author Report Share Posted October 20, 2013 Ok, I'll check the engine sprocket, then I'll get a 13/60 final drive sprocket combination made up. Regards David Quote Link to comment Share on other sites More sharing options...
farmer58za Posted November 8, 2013 Author Report Share Posted November 8, 2013 I have taken a look at a spare villiers front sprocket from the Cheetah spares. This one is an 18 tooth - part number E9149/1. If I have to replicate this with only 13 teeth the raised centre boss at the rear of the sprocket looks like it will be too large to clear the chain. Does anyone have details of a 13 tooth sprocket for me? Thanks David Quote Link to comment Share on other sites More sharing options...
laird387 Posted December 23, 2013 Report Share Posted December 23, 2013 Hi, David, One point that many people miss when looking at gearing is how many slippy, slithery surfaces are you likely to meet? The reason that I ask, is that the larger the rear wheel sprocket (i.e. the closer the chain line to the wheel rim), the greater the tendency for traction to be broken very easily. If you watched Sam the Man on surfaces like that, he would very often find grip that nobody else could, but he would always have a tiny primary drive sprocket and less teeth on the rear than most. It's a simple fact of physics, greater leverage on the circumference of any circular object the closer one applies the force to the rim. That's why we select second to pull away on mud or ice, rather than first which will just spin the wheel. Good luck Quote Link to comment Share on other sites More sharing options...
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