After a few frustrations testing out some direct chain drive methods (basically variations on the above using first a scooter motor and then a radiator fan motor, on a Kensington junk bike) I decided to try out friction drives, based on some of the concepts I found on Jim Rudholm's
. It looked easy enough, and should in theory work fine as long as it's dry. This *is* Phoenix, Arizona, so it is dry enough to work 99% of the time, maybe more.
EDIT: links above are dead, so here's the archived version on the wayback machine:
http://web.archive.org/web/200807311404 ... cbike.html
I thought I'd use the K.I.S.S. principle, and try it out the "easy" way first, which I was pretty sure wouldn't work or at least keep working, and I was right. So this was Friction Drive 1.0.
I just took a rackmount front panel blank and cut holes big enough for the pair of Toyota radiator fan motors (radial brushed) I had gotten from a junkyard, to fit thru it and line up with the rear wheel.
The batteries went in the rear rack. I shoudl've moved them forward, but that didn't happen till a lot later. They're just 12V12Ah SLA, used, from either a scooter or a UPS, I can't remmeber which. The 7Ah in the forward left basket corner is my lighting battery.
Dunno if you can tell, but that poor little kickstand is curving from the weight on it, which wasn't that much yet.
I used the controller out of a ScootNGo I'd gotten as a carcass. The controller had blown FETs and a melted relay, and the board was burned so bad I had to mount the replacement FETs externally.
Tension was controlled by a lever-type shifter pulling down on the rear end of the rack plate, with it's pivot being one of the rack mounting tab notches hooked into the front edge of the basket. No, it wasn't very good or stable.
I left the plastic hubs of the fans on, just cutting off the blades and roughening the surfaces a lot (it wasn't enough).
There were a few failures right off. The first was breaking the hollow adustable-length kickstand, made of some cheap cast aluminum.
Then I blew up some (a lot, actually) MOSFETs, not surprising since I salvaged all of them from various old UPSs, motherboards, and so on, and I don't think I even checked the specs on most before throwing them on there.
Then a few potholes later,
I broke off the plastic hubs from the aluminum centers that bolted to the motors. Pressure in the tires makes air transfer from the bottom to the rest of the tire, slightly expanding it all over, when you hit bumps or holes. That flexes anything on a shaft pressing against it, and I should've realized that from the start.
Not only that, but I shoud've realized what that would do to v2.0.2, before it did. More on that later.
This is the replacement stand, which worked better, but not for very long. I'm just glad it was a donation and not out of my pocket.
The plastic you see above the spring is surrounding a VERY thin aluminum tube that's riveted up at that silver rivet head for a pivot. The plastic cracked and then the aluminum just sheared thru, after not a lot of use but with lots of heavy groceries/etc.
Since I had them, I used the scooter's power meter and keylock.
as well as it's turn signal switch and horn button. The horn sucked so I took it off. It wasn't loud enough to help but was annoying to me.
Also visible is the red-cabled tension adjuster for the drive.
After the fan hubs broke off, I began a quest for version 2.