Cut-Rate Recumbent Bike

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To save a lot of trouble later, you'll probably want to paint your recumbent's frame now ... and while that finish is drying, you can assemble the E.M.T. "mag" wheels. The front units are made by welding 1" X 3" conduit hubs to the 20" rims with 7 1/8" sections of 1/2" E.M.T. (A plywood jig table, with a 1 3/16" hole drilled in its center, and bolts or dowels set to hold the rim true, should guarantee perfect results every time ... especially if you use spacers to lift the spokes and/or the rim to the necessary height.) The rear wheel is of a similar construction, but the spokes are slightly shorter (because the hub is bigger), and you should remove the gearset before doing an), heavy welding.

Your choice of front wheel bearings will be determined by the use to which you plan to put the recumbent. If the trike is to be simply a child's toy, some brass sheet stock can be cut, formed, greased, and then slipped between the hubs and the spindles. For a more sophisticated approach, Delrin (a composite material available through industrial supply houses) rod can be cut and filed — or machined — to serve the same purpose, and has the added benefit of' natural lubricity. Either way, the wheels will be held to their spindles with 1/2" bolts and washers.

A 32 1/4" tie rod connects the two steering knuckle arms ... but, since the machine's toe-in must be adjustable, we've welded a 5/16" nut into each end of the 112" linking tube and threaded in a pair of rod-end ball joints with locking nuts. These are — in turn — fastened to the flattened ends of the arms with 5/16" X 1" bolts. (Once you've set the toe-in at 1/8", you can weld machine-nut stops to the rear of the axle tube to keep the knuckle arms from traveling too far and allowing the tires to rub the frame.)

Finish Up and Fly

At this point, you should be ready to install the crank assembly, the rear wheel, the brake caliper and hand lever, both handgrips, the rear fender, the flag, and the reflector ... and the generator, if you're using lights. Keep in mind that when you run the control cables for the brake and shifter, you'll have to ascertain where — as determined by the length of cable you're using — to weld the 7/32" nuts that will hold the plastic housing ends in place.

The chain (which is actually three 55" lengths of standard bike links clipped together) has to make one angle in its travels. To alleviate friction at that point beneath the front axle, we again used a block of Delrin composite as a buffer. An alternative, though, would be to install a spool, a roller, or a pair of sewing bobbins at that location, and allow the links to ride on this "wheel." Also, to prevent the chain from wandering sideways, we made up a small guide consisting of a 2 1/4" X 3 plastic tongue bolted to a small bracket), which clamps to the right front radius rod and can be adjusted as necessary. Note, too, that we used a disk-type guard on the crank sprocket, though a conventional chain guard might be a better choice if children will be riding the machine.

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