A quick question. Why do they not make sportbikes with shaft drives?

 

This is just a guess, but I'm thinking of 2 reasons. One is weight, which I bet is the main reason. The other is I wonder if a chain/sprockets isn't a more efficient way to transfer power to the wheels, thus ending up with more power to the wheels. Oh and I'm sure traditions plays in too.

 

Chain Drive is light, highly efficient, inexpensive, and allows you to relatively easily change your motorcycle's final drive ratio. However, it requires regular lubrication, cleaning, and tension adjustment.

Shaft Drive is heavier, almost but not quite as efficient, somewhat expensive, and makes it impractical to change the final drive ratio. However, the maintenance intervals are much farther apart.

 

A good question, having owned a few shafties I've often pondered that one. I believe that it goes down to the fact that they add considerable weight, a bike will loose about 10% (or so) of power to the rear wheel & a slight delay in the transfer of power from the motor to the shaft to the wheel. And no matter what the engineers do, you will always get a rise & fall at the front of a bike when you hit the throttle. Shafts are pretty reliable though, you will hear stories of how they got bent, ceased etc (one of the true ones I can attest to, is when the the oil seals go & they spew a litre of gear oil over your rear tyre), but no more than the horror stories you hear about chains.
Shaft drives have always been associated with Tourers, but a few makers have made
"Sport style" bikes over the years.
The benefits of a shaft though is the lack of maintenance (apart from checking the oil level every so often & changing it as per the maintenance schedule), you never have to adjust the rear wheel for straightness.
I found shaft drives to be fine once you get used to them & depending on the bike, you can still throw a decent mono on them.
One of my old "Tourers"

 

the biggest reason you dont see em on sportbikes is because a shaft driven bike has a tortional effect under power wich means the bike tries to "stand up" under power. if you have ever rode a bike with a shaft it seems it wants to lift up when you get on it hard. during the turns the bike seems to want to upright under haRD accell during the turn, no-good for a sportbike that is ment to lean hard and carve up corners. but just to be clear i love shaft drive bikes ...

 

everythings already been said, but I'll add my input. Chains are very efficient and don't rob hardly any power. Turning a light chain and sprockets is more suited for performance than turning a large shaft, with gears, spinning in thick oil.

shaft drives have thier place, but its not on a sportbike. I couldn't imagine a 150hp bike (well, 125 after the shaftdrive), trying to hook up. Shaft drives make the bike loose traction because they push the weight of the bike over the front tire as you accelerate. The harder on the gas, the more rear traction that is lost. With lightweight high hp bikes, it could be a dangerous combination.

You'll notice they put shaft drives on certain bikes. If they are fairly light, they will be low hp. If they have higher hp, they are very heavy. never on light weight and high hp.