Hi all,
I have a bit of a head scratcher re. the gearing of my new-ish TDS Scottish. After struggling a bit with slow speeds on a recent trial, it was suggested I look at something like a 12 tooth drive sprocket and 60 tooth rear wheel sprocket. I bought the 12 toother; clutch, primary chain and casing off only to find....it already has a 12 tooth drive sprocket fitted. Looking a little deeper and counting revolutions of clutch against drive sprocket whilst in each gear, it would appear I have the 'road' gear cluster fitted rather than the trials. I gather this wasn't uncommon as back in the day these bikes may have been used for daily transport through the week and trials at the weekend.
So what I now have is the road gearbox ratios (which are obviously too high for trials), a 12 tooth front sprocket (which lowers the gearing so far), and a 56tooth rear sprocket. My question is, how much bigger to go on the rear sprocket. Will a 60 tooth rear lower the gearing sufficiently or should I go bigger. (Villiers services offer up to a 66 tooth sprocket). I suspect this may be a try it and see issue, ( or there may be a complicated calculation that would make my head hurt) but wondered if anyone had a similar problem in the past.
cheers
Paul
I have a bit of a head scratcher re. the gearing of my new-ish TDS Scottish. After struggling a bit with slow speeds on a recent trial, it was suggested I look at something like a 12 tooth drive sprocket and 60 tooth rear wheel sprocket. I bought the 12 toother; clutch, primary chain and casing off only to find....it already has a 12 tooth drive sprocket fitted. Looking a little deeper and counting revolutions of clutch against drive sprocket whilst in each gear, it would appear I have the 'road' gear cluster fitted rather than the trials. I gather this wasn't uncommon as back in the day these bikes may have been used for daily transport through the week and trials at the weekend.
So what I now have is the road gearbox ratios (which are obviously too high for trials), a 12 tooth front sprocket (which lowers the gearing so far), and a 56tooth rear sprocket. My question is, how much bigger to go on the rear sprocket. Will a 60 tooth rear lower the gearing sufficiently or should I go bigger. (Villiers services offer up to a 66 tooth sprocket). I suspect this may be a try it and see issue, ( or there may be a complicated calculation that would make my head hurt) but wondered if anyone had a similar problem in the past.
cheers
Paul
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