Gearing
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knackeredMk1
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- Joined: 03 Nov 2006, 17:41
- Bike Owned: Modified Mk1
Gearing
All CRM250 gearbox 'gears' are interchangable. So you can swap one Mk with another. Mk2/3/AR basically have the same gearing but the Mk1 is a tighter box.
Copied from Honda Mk2 briefing document (dotted line is Mk1. Mk2 is 'New CRM') -
Japanese SuperMoto riders often swapped later gear ratios/cogs (5th & 6th) for Mk1 cogs to get closer ratios. If you are going to swap gears then beware that Mk2/3 & AR are easy to swap complete with the shafts but the clutch shaft on a Mk1 runs on a 1mm larger diamter bearing than the others. So to swap ratios you need to swap cogs and keep the same shaft, grind out the Mk2/3/AR bearing or bush/weld the smaller shaft to make it bigger.
Mk2/3/ARs have a 6th gear ratio that is ~ 7% higher than a Mk1.
Sprocket ratios have a big effect on acceleration/top speed/cruising speed. As do wheel and tyre sizes.
Sprocket ratios vary a lot between riders but those who do Greenlaning or Long Distance Trials only tend to use 14:45.
Those who race tend to use lower ratios ~ 13:45
SuperMotos ~ 15:42
You can get the exact ratio by dividing the rear sprocket teeth by the front sprocket teeth so different sprockets can give you virtually the same gearing. E.G. 14/45 = 3.2143. You can get essentially the same gearing by using 13/42 or 15/48, so one tooth on the front ~= three teeth off the back.
Jeram has put the AR on to the 'Gearing Commander' -
http://www.gearingcommander.com/
If you have a rear sprocket larger than ~45 teeth you need to use a dropper plate between the swing arm and the chain guide -
Otherwise you will wear the chain and the guide. A small amount of adjustment can be achieved by working the holes in the chain guide for the mounting bolts.
Copied from Honda Mk2 briefing document (dotted line is Mk1. Mk2 is 'New CRM') -
Japanese SuperMoto riders often swapped later gear ratios/cogs (5th & 6th) for Mk1 cogs to get closer ratios. If you are going to swap gears then beware that Mk2/3 & AR are easy to swap complete with the shafts but the clutch shaft on a Mk1 runs on a 1mm larger diamter bearing than the others. So to swap ratios you need to swap cogs and keep the same shaft, grind out the Mk2/3/AR bearing or bush/weld the smaller shaft to make it bigger.
Mk2/3/ARs have a 6th gear ratio that is ~ 7% higher than a Mk1.
Sprocket ratios have a big effect on acceleration/top speed/cruising speed. As do wheel and tyre sizes.
Sprocket ratios vary a lot between riders but those who do Greenlaning or Long Distance Trials only tend to use 14:45.
Those who race tend to use lower ratios ~ 13:45
SuperMotos ~ 15:42
You can get the exact ratio by dividing the rear sprocket teeth by the front sprocket teeth so different sprockets can give you virtually the same gearing. E.G. 14/45 = 3.2143. You can get essentially the same gearing by using 13/42 or 15/48, so one tooth on the front ~= three teeth off the back.
Jeram has put the AR on to the 'Gearing Commander' -
http://www.gearingcommander.com/
If you have a rear sprocket larger than ~45 teeth you need to use a dropper plate between the swing arm and the chain guide -
Otherwise you will wear the chain and the guide. A small amount of adjustment can be achieved by working the holes in the chain guide for the mounting bolts.