Unless you ride GP bikes for a living, you're unlikely to ever notice the secondary effects of changing sprockets and what that does to the handling of a motorcycle. Regardless, its interesting to study, and has some practical applications too when you are deciding how to obtain a ratio.
The chain used on the Falco, a "525" chain, has a pitch of 5/8ths of an inch (we know this from the leading "5" in "525"). So, dropping a tooth off the front or rear sprocket changes the circumference of the sprocket by 5/8ths of an inch. This requires a radius reduction of 5/8ths, divided by two times pi. What this means to us is that if the same chain is used and a sprocket is changed, substracting a tooth from either sprocket increases the wheelbase by 2.5 mm. Adding a tooth reduces the wheelbase by 2.5 mm.
We should first be concerned because there is a limited amount of adjustability in the wheelbase, given by the length of the axle slot in the swingarm. Some ratios will not be able to be obtained without changing chains. Adding one link to a chain will lengthen the wheelbase by half of 5/8ths of an inch, or 7.9 mm. Deleting a link will reduce wheelbase by 7.9 mm.
| Final Ratios and Wheelbase Compared to Stock | ||||
| Countershaft sprocket | Chainring | Final Ratio | Change in Wheelbase | Stock Chain? |
| 16 | 41 | 2.56 | 0.0 mm | Yes |
| 16 | 42 | 2.63 | -2.5 mm | Yes |
| 16 | 43 | 2.69 | -5.1 mm | No |
| 15 | 41 | 2.73 | +2.5 mm | Yes |
| 16 | 44 | 2.75 | -7.6 mm | No |
| 15 | 42 | 2.80 | 0.0 mm | Yes |
| 15 | 43 | 2.87 | -2.5 mm | Yes |
| 15 | 44 | 2.93 | -5.1 mm | No |
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