Jeff Caswell's Wheels 'n Things

Jeff Caswell brought the wheels intended for his new Super Microbike. They are 406 20" wheels, larger than he prefers for a compact low racer but selected so he could use his new favorite tire, the Tioga Comp Pool. They are fat but supple and roll very well (best in testing by Greenspeed's Ian Sims, though Mark isn't sure if Ian's small roller tests really generalize well to road use on a flat surface). He uses an aero section Velocity rim, and puts all the spokes exiting from the inside of the flange so he can put on a disk cover that rests even with the outer surface of the flanges. The disk cover is polypropylene plastic (from IASCO in St Louis Park) assembled using matching red electrical tape.

The new bike will have right side front wheel drive from an intermediate gearing system using another of his favorite components, the Shimano Nexus 7-speed hub. It may not have the range of a Rohloff hub, but it is much cheaper and shifts under greater load and has adequate range for a racer. Mark seconded the motion about its shifting under load, since the Shimano Nexus 4-speed is now used in rental fleets with an automatic shifting controller. It has been pretty bullet-proof in that application, where the rider will get no warning that a shift is about to happen and thus will routinely shift under heavy load.

Jeff also showed off some frame bits scavenged from the famous Trek dumpster in Wisconsin. They cut most frames into pieces before trashing them, but pieces are just what you need sometimes for a home-built recumbent. He has just started doing serious metal cutting for his new frame. So far he plans on using rather small diameter but heavy wall (0.058” probably) tubing as the main backbone tube. But Mark strongly recommended going the other way, since larger diameter is the most efficient way to get good strength and stiffness in a backbone tube.

I think the tube he's using is 1.125" x 0.058". This tube would only be 36% as stiff as the 1.5" x 0.065" tube on his MicroBike, which required carbon wrapping. A piece of 2.00" x 0.035" would be 3.75 times as stiff, but only 11% heavier. M.S.

Finally, he showed a newly scavenged molded plastic seat to serve as the next generation of the cut down kitchen chair on the first Microbike. It is a high priced Eddy Bauer child's car seat, but he swears he can cram himself into it (and even get out of it, which is harder still!). He will cut it down substantially, which will help on weight and maybe also make it a little more flexible and spreadable. He hopes to have a fairly complete bike by the next meeting in June.

Jeff found a molded plastic garden cart wheel from Northern Hydraulics that he wouldn't use on his personal racer but would consider using on a low price production version of the Super Microbike. It has a very narrow hub and pretty decent bearings, though the low pressure rating typical of molded plastic wheels could be a problem.


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