http://en.wikipedia.org/wiki/Shaft_effect

http://en.wikipedia.org/wiki/Swingarm#Squat_and_Sky-jacking

Depends entirely on the bike.

Frikking Beemers have the drive shaft offset from the axle pivot. So when you're hard on, or hard off the throttle, the suspension is being crabbed up or down by the engine torque twisting against the rear axle. The greater that offset, the greater that torque affect. True for 60's, 70's, 80's and 90's Beemers, haven't ridden one after 2001, but they still had that torque factor jacking the suspension.

Not sure of the others, but for their shafties, Honda, Kawasaki engineered their rear drive such that the drive shaft was perfectly aligned with the rear axle. This prevents the torque angle from causing the rear suspension to get jacked up by the engine torque during hard accel and hard decel. Put 30k on Wings and another 50k on Concours... and IMHO both of these were very smooth and neutral in terms of how the suspension behaved when whacking the throttle open / closed. (yes, I have wrist control problems, Officer :dancecool: )


Having ridden dozens of bikes of most brands, that fact always kept me from choosing a Beemer (despite still lusting after the black and yellow Bumble Bee GS to this day).

Your mileage may vary.

For me, the main difference is convenience. Lube the shaft drive every 10,000 miles with high moly grease versus cleaning and lubing a chain every 500 miles or so and replacing chain and sprockets every 20,000-25,000 miles. I wish all bikes were shaft driven!

There is some loss of power with most shaft drives that doesn't occur with chain driven systems.

Maybe I am crazy, but I enjoy cleaning and lubing chains on my motorcycles. Very Zen. Feels good, easy accomplishment.

Having ridden dozens of bikes of most brands, that fact always kept me from choosing a Beemer (despite still lusting after the black and yellow Bumble Bee GS to this day).

You'd need to ride a more modern bike. Whether BMW, Kawi, Yamaha, or Honda at this point, shaft-jacking just isn't an issue anymore. Each of the manufacturers has put in geometry (in different ways) to combat it pretty much entirely. The more noticeable issue is driveline lash. In high-horsepower shaft drive bikes (some exceeding 150hp at this point), it seems that the manufacturers have to put in quite a bit of play/slop somewhere in the drivetrain to keep it from failing under strain. More noticeable on my K16 than any of the boxer 12s, but also noted as a concern on the new Kawi Concours. It's talked about less on the FJR, so maybe Yamaha has a handle on it.

For me, the main difference is convenience. Lube the shaft drive every 10,000 miles with high moly grease versus cleaning and lubing a chain every 500 miles or so and replacing chain and sprockets every 20,000-25,000 miles. I wish all bikes were shaft driven!

There is some loss of power with most shaft drives that doesn't occur with chain driven systems.

Ditto. The lack of a chain is probably what I miss most about my VN700. Another VN750/EX500 guy on the 500 forum was talking about how much easier it is to maintain the chain constantly than to lube the shaft while you're changing the tire, and I figured he was on crack or something.