What are the pros and cons of belt driven motorcycles compared to chain driven bikes?
Belt vs Chain in Motorcycles
It's difficult to say which one is better. Depending on the application, one can be better or not in the particular role. High horsepower applications are not the place of belts and low maintenance is not the place for chains. Applications vary and one is not necessarily better than the other overall. The role of the final drive decides which final drive is best suited for the application.
Pro's for Chains
Chains have more strength for higher performance/high HP applications
Broken chains can be fixed with a new master link
Final drive ratio is easily changed through various sprocket size changes and combinations
Con's for Chains
A chain failure can be catastrophic, potentially puncturing and engine case when they fail
A chain has considerably more inertial mass than a belt
Chains weigh up to 10 lbs and are heavy
Chains require regular maintenance and require ongoing adjustment throughout their life
Chains require lubrication that can get flung about and require ongoing cleaning
Pro's for Belts
Belts are very light
Belts rarely do damage to the vehicle when they fail
Belts can last up to 100,000 miles, longevity
Belts require very little maintenance, lower operation cost
Belts are have a lower cost per mile than chains
Belts transfer power more efficiently than chains
Con's for Belts
Difficult to repair on the side of the road
Less strength than a chain
Here are some reasons why some manufacturers use belts.
- Smoothness of the drive: The belt has the quality of putting down the torque of the engine much more smoothly and gradually than the chain counterpart, in a belt driven motorcycle you wont feel the sudden TUG when you twist the throttle.(This is the reason usually cruisers have this design and not the super-bikes but there are exceptions)
- 0 Noise:There is literally 0 noise in the belt driven design compared to a chain drive which will need constant tightening in order to avoid rattling noise which might be unpleasant, belts however do not emit any kind of noise way until their last leg of useful lives.
- Better for dusty environment: Belts do not accumulate dust or dirt and need far less maintenance when compared to chain driven design , thus causing very low maintenance.
Source: My friend works at Harley Davidson India and I asked the exact same question to him some time ago.
For Issues with the chain drive I think Ducatikiller has explained in his answer.
This is more additional points to the above (good) answers.
With cost per mile it probably depends a lot on the OE parts prices. With the old Kawasaki belt system used in the 1980s they lasted maybe 50% longer, but failed with little or no warning and cost a LOT more to replace (plus the far greater labour to change them).
Belt life on Buells does not seem that long, while they are not ultimately that high power. Possibly down to the amount of suspension movement and its effect on belt tension.
Further in some countries automatic chain oilers are available which greatly reduce chain maintenance.
Chains are more efficient when new, but that efficiency reduces with wear. Hence soon a belt does become more efficient. This I have heard as the primary reason why belts are not used in GP racing, as the chain is likely to be binned long before its efficiency degrades.
For some uses the difficulty in changing pulley wheel sizes to alter gearing will be a major issue. Some of this could be overcome (more belt adjustment margin to allow a greater range of pulley wheel sizes), but that still leaves a significantly higher cost for alternative sizes of pulley wheels compared to sprockets, and the impossibility of doing the equivalent of taking a couple of links out of a chain (or indeed the impossibility of swapping out a belt in a hurry without removing the swinging arm).
Belts are quieter than chains (which might become more of an issue as noise laws get tighter).