loquin
Well-Known Member
A centrifugal clutch can only transfer so much torque before it starts to slip. The slippage is the clutch shoes moving past the clutch drum. This wears the clutch pads, and to a lesser extent, the clutch drum. You rev the engine to speed up, and the motor is putting out more torque. If the sprocket/gearing ratios are too high, the pads on the clutch cannot transfer enough of the torque through to the axle and the clutch slips.
A larger wheel, this reduces the overall engine to road speed ratio. Because the circumference is larger, the tire doesn't need to rotate as fast to maintain the same ground speed as a smaller tire. The engine is therefore running at slower RPMs to maintain the same ground speed.
The higher the gear ratio, the greater the acceleration, as there will be more torque available at the rear tire. (Discounting frictional losses, the result of RPM time Torque is the same at the engine, and at the rear axle, and at any point (gear or sprocket) in between. Low RPM equals High Torque, and vice versa.) Since a higher acceleration means that the bike gets up to speed faster, there will be less time that the clutch slips before getting up to speed. Less time spent slipping means less time grinding away at the clutch shoe pads and subsequently, less wear...
On the other hand, lowering the ratio, (increasing rear wheel diameter lowers the ratio) also lowers acceleration, which increases the amount of time spent slipping the clutch...
You have to make a conscious decision as to as to which factor has a higher priority for you - better acceleration and hill-climbing ability, or a greater top end speed. That way, you can come to the right compromise for your situation.
A larger wheel, this reduces the overall engine to road speed ratio. Because the circumference is larger, the tire doesn't need to rotate as fast to maintain the same ground speed as a smaller tire. The engine is therefore running at slower RPMs to maintain the same ground speed.
The higher the gear ratio, the greater the acceleration, as there will be more torque available at the rear tire. (Discounting frictional losses, the result of RPM time Torque is the same at the engine, and at the rear axle, and at any point (gear or sprocket) in between. Low RPM equals High Torque, and vice versa.) Since a higher acceleration means that the bike gets up to speed faster, there will be less time that the clutch slips before getting up to speed. Less time spent slipping means less time grinding away at the clutch shoe pads and subsequently, less wear...
On the other hand, lowering the ratio, (increasing rear wheel diameter lowers the ratio) also lowers acceleration, which increases the amount of time spent slipping the clutch...
You have to make a conscious decision as to as to which factor has a higher priority for you - better acceleration and hill-climbing ability, or a greater top end speed. That way, you can come to the right compromise for your situation.
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