Using a worksman drum hub

[californiakevo]

Hey guys,

Kevin here... Long time lurker first time poster. Building a board tracker from a Worksman bike with front and rear drums and the honda 49cc ghx kit. I've noticed that alot of guys are using the worksman wheels, just wondering if anyone is using the worksman rear drum wheels with these things and if so how you're mounting the drive sprocket from the engine onto the drum hub. We were thinking of mounting the sprocket on the left side of the hub on that lip that sits between the spokes and the drum assembly if that makes sense. Would love to know what everyone else is doing as I'm running on pure speculation at the moment. Thanks!

Kev

 

[Board Track Racer]

Check out post #68. Hope this helps.

http://motorbicycling.com/f38/new-boardtrack-project-w-honda-engine-11098-7.html

 

[dmar836]

Kev,
Welcome. Several of us have done that but it is a questionable method, if I can speak for the others. It has worked for our bikes that don't see regular service but is fundamentally unsound for a road bike. I say this as cush drives were found to be necessary all the way back in 1910 or so. The prior belt drives didn't need it but chain slack does nothing to absorb the stress of the constant vibration and intermittent power pulses from an engine. It was for this reason that there were many advocates for the belt drive design well into the chain drive era.
Aluminum has only so many stress cycles before failure - maybe 5000, maybe 300,000 but it will eventually fail from stress it isn't designed to handle. If you could hard rubber mount a sprocket carrier, you'd be ahead in the design department. I couldn't configure one with this particular hub but there are some sharper people than me on here.
Dave
KC

 

[dmar836]

If I may, there isn't a much simpler cush drive to illustrate the point than what Yamaha came up with.
You can see the sprocket carrier is laterally supported by bearings(though there isn't that much) and is rotationally bound by the four tabs that fit snugly into the rubber pads. Those rubber pads fit snugly into the hub. Lots of alloy meat all the way out to the carrier.

As you can see, the other side has a floating carrier for the brakes similar to the Worksman hub.

I feel the center of the Worksman hub would need to be substantially heavier in order to support bearings for a the axle further out near both a floating sprocket carrier AND the existing brake carrier. Perhaps something could be built externally to mount to a carrier, perhaps with bonded rubber inserts (ala RD400 mag wheels except in the carrier and not the hub) but then the stress factor on the hub in shear comes into play again.
I have two sets of RD 400 cast wheels but both are on bikes so I cannot photograph them. It's a much more compact arrangement. A google search might help there.
Dave