The Gearbox Thread

[koba]

People, please post useful gearbox info here!

Chris C has posted this elsewhere, the standard FXR150 ratios:

Primary reduction - 3.5 (70/20)
Final reduction - 3.428 (48/14)

1st - 3.000 (33/11)
2nd - 1.857 (26/14)
3rd - 1.368 (26/19)
4th - 1.095 (23/21)
5th - 0.923 (24/26)
6th - 0.800 (20/25)

I'll add to that with an MB50 Setup:

Primary reduction - 4.117:1
Final reduction - 2.33 (35/15)

1st - 3.1666(38/12)
2nd - 2.0625 (33/16)
3rd - 1.5000 (30/20)
4th - 1.1739 (27/23)
5th - 1.0000 (25/25)
6th - 0.8846 (23/26)

[chrisc]

Try this
http://www.gearingcommander.com

I've loaded up a few rations for different bikes.

Bert posted this^
Worth a look for sure. I really like the table showing speeds using different rear sprockets but the layout is very difficult to follow and look at.

I work on an excel spreadsheet that a made based on calcs on John Bradley's "The racing motorcycle" book. Well worth a read. He writes about gearing and sprockets on a fairly detailed level when discussing the selection of an engine for building a one off bike.