reewheel adapter for square taper spindle

I'm looking for a freewheel adapter for a square taper spindle that can accommodate two freewheels. I've seen threaded cranks but they only accommodate one free wheel http://sickbikeparts.com/catalog/product_info.php?cPath=21&products_id=35. I've attached a picture of what I'm looking for. I'm starting a new project on a tandem bike where the motor chain attaches to the rear passengers bottom bracket. easy shift kit. any help you can give would be appreciated. peace

Bottom bracket jackshaft

Do this. Easy conversion.

That's exactly what i need. where did you get the parts?

The freewheel adapters, 5/8 keyed shaft, & sprockets are from Staton-Inc. The bearings are fit to the European bottom bracket adapter by dremaling the threads to fit tight. Dave Staton also sells threaded bearing holders. Check out his Giant Stilleto kit. I have used those as well on another bike. Here are some more pics. This jackshaft can be driven from either side. I actually first built it to drive on the right side. It now drives on the left.


http://www.motoredbikes.com/attachment.php?attachmentid=485&d=1187127551

http://www.motoredbikes.com/showthread.php?t=6335