The Thread Spread - Revisited
_______________________________________
-Chains-
Power Loss So Plain
The question - Is there any advantage of running larger sprockets for more mechanical advantage ... with the same final ratio?
The response - In a word - no. The final ratio is the final ratio. The countershaft will still turn the same number of revolutions to make the rear axle turn the same number of revolutions.
Rick
I think you'll find that the wear rate of the chain is quite noticeably reduced when it bends around a 15/45 sprocket combination as opposed to a 12/36 alternative, for example. The radii are larger and therefore the chain bends less, thus it wears more slowly and there is also less parasitic horsepower loss. The ratio remains the same however.
High Output
- I agree with that. Most recently I have seen dyno tests with worn chains/sprockets that robbed motors of several HP on high HP street bikes. It makes sense that turning tighter corners eats some HP due to more friction- I just wonder if you can measure it.
Rick
- I started thinking about the extra weight of the longer chain, the extra weight of the sprockets and wondered if the extra power required to rotate this additional weight would be of any advantage after all.
- As far as chains go... I consider them throw away items. I used to buy real expensive ones, sometimes I'd even spring for the color plated ones because they looked so cool. I really thought the extra money I spent on them was buying me a better chain. I also had to learn the hard way that in a sand environment aluminum sprockets are a no-no too. I was busting the teeth off of them after only a day of racing. The sand just tears up aluminum sprockets and it doesn't care if you spent $110 on a chain either. These days when I put on a new chain and steel sprockets and go on a trip to Glamis I have to adjust it a couple of times a day the first day or two. Then maybe once a day for the rest of the week. When the week is over the chain is toasted. I trash it and get a new one. The steel sprockets are usually able to last a little longer. O-ring chains last longer, but the power they draw is tremendous - much too much to tolerate.
Rick
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