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View Full Version : Output sprocket / swingarm pivot in line



jellywrestler
30th July 2010, 11:23
I've got two bikes with the final drive sprocket in line with the swingarm. It's one of those ideals in motorcycle frame design that means as the suspension goes through it's travel the chain stays a constant length that very few manufacturers used.
Hesketh went to the trouble of putting an extra shaft into the gearbox to accomadate this and keep the engine narrow, and there fore the frame. Photo shows my Bimota SB3 which as they had sourced the standard engine from Suzuki, they had to build a very wide frame to wrap around the engine.
What other bikes had this designed into them

Grumph
30th July 2010, 16:04
Aside from possibly one or two in the Vintage era I think you've got the only two manufacturers that ever bothered to do this.
Modern theory says put the pivot point where chain pull torque reaction will assist traction.

Voltaire
30th July 2010, 16:54
The BMW 450 dirt bike has the swingarm thru thru the drive sprocket....

Motu
30th July 2010, 17:49
Coaxial I think you would call it - having the swingarm pivot and output sprocket inline is another design ideal...axles,crankshaft,output sprocket and swingarm pivot all in a horizontal line.

Apparently the BMW is very sure footed in slow going over ruts,rocks and tree roots as there is no torque reaction through the swingarm.

F5 Dave
2nd August 2010, 17:19
Spondon did one for a Laverda engine. erm, seem to remember a PB poster on the wall as a lad with a buxom lass on it, Tracey Neve or summit.