Just a general point, seeing all the wild variations people are talking about. A one-tooth change on the front can make a massive difference. I've just sold a Ducati GT1000 which came as standard with 15/45. It was way over-geared for the road, with sixth gear useless below 80mph and first gear required for slow corners. I changed the front sprocket for a 14T, and the difference was amazing, with 2nd-gear corners taken in 2nd, and top gear a useable road ratio. And that was with a gearing down of only about 7%.
What I am saying is not to be too radical when changing gear ratios. A little change goes a long way, especially on the front. I would change one tooth at a time and see how it goes. Sprockets are cheap enough. I was advised not to go below 14 on the front, though, for reasons of wear as mentioned by Mollydog. If you need to go lower than that, go up on the back, roughly 3 teeth per one tooth on the front. Then you start getting chain length issues, and so it goes ...
|