Westy123
24th October 2011, 06:48
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Using the Suzuki DRz-400 as an Adventure bike has one major frustration for me and that is the five-speed gearbox. Well, not the gearbox as such, but the closeness of the ratios. If the bike is geared for tight or difficult terrain then a comfortable touring speed in open going sees the engine revving harder than I like for longevity. Conversely, if it’s geared for cruising at moderate revs, then first gear is too high for easy riding in tricky terrain and the clutch risks being punished..
The standard Suzuki ratios are: 1st gear = 14:32 (0.44), 2nd gear = 15:26 (0.58), 3rd gear = 16:22 (0.73), 4th gear = 22:24 (0.92), and 5th gear = 22:19 (1.16). A calculation shows that the steps between the ratios is (approximately) 24%, 20%, 20%, 20%, which are unusual spacings – generally the gaps are closer in the higher gears, due to the importance of maintaining revs nearer the bike’s peak torque because of increasing drag . While it is true that wind resistance increases with the square of increasing speed, the power needed to overcome that resistance increases with the cube. The new ratios that I have had made, installed and tested are: 1st gear = 14:32 (0.44), 2nd gear = 19:29 (0.66), 3rd gear = 23:24 (0.96), 4th gear = 29:24 (1.21), and 5th gear = 28:20 (1.40). They have much more useable steps of (approximately) 33%, 31%, 23%, 13%.
Its first outing on a steeply rutted clay track proved that the wide ratio gearbox feels normal in its operation, allowing the 400 to climb rough hills without distress, lugging, or clutch slipping to maintain revs. Later, on the sealed country roads the DRz cruised along at relaxed revs in top gear yet still had sufficient torque on hand for decent acceleration. So a great result and a transformed bike for ADVriding!!
Pictures here -
http://s1224.photobucket.com/albums/ee375/westhayes/DRz400%20wide%20range%20gearbox/
Using the Suzuki DRz-400 as an Adventure bike has one major frustration for me and that is the five-speed gearbox. Well, not the gearbox as such, but the closeness of the ratios. If the bike is geared for tight or difficult terrain then a comfortable touring speed in open going sees the engine revving harder than I like for longevity. Conversely, if it’s geared for cruising at moderate revs, then first gear is too high for easy riding in tricky terrain and the clutch risks being punished..
The standard Suzuki ratios are: 1st gear = 14:32 (0.44), 2nd gear = 15:26 (0.58), 3rd gear = 16:22 (0.73), 4th gear = 22:24 (0.92), and 5th gear = 22:19 (1.16). A calculation shows that the steps between the ratios is (approximately) 24%, 20%, 20%, 20%, which are unusual spacings – generally the gaps are closer in the higher gears, due to the importance of maintaining revs nearer the bike’s peak torque because of increasing drag . While it is true that wind resistance increases with the square of increasing speed, the power needed to overcome that resistance increases with the cube. The new ratios that I have had made, installed and tested are: 1st gear = 14:32 (0.44), 2nd gear = 19:29 (0.66), 3rd gear = 23:24 (0.96), 4th gear = 29:24 (1.21), and 5th gear = 28:20 (1.40). They have much more useable steps of (approximately) 33%, 31%, 23%, 13%.
Its first outing on a steeply rutted clay track proved that the wide ratio gearbox feels normal in its operation, allowing the 400 to climb rough hills without distress, lugging, or clutch slipping to maintain revs. Later, on the sealed country roads the DRz cruised along at relaxed revs in top gear yet still had sufficient torque on hand for decent acceleration. So a great result and a transformed bike for ADVriding!!
Pictures here -
http://s1224.photobucket.com/albums/ee375/westhayes/DRz400%20wide%20range%20gearbox/