Friction generator

I don't know much about troubleshooting links, but I bought a generator powered light kit on closeout from Target. I plan on installing it as intended some day. No light when stopped does not bother me much.
 
These were not designed for excess speed, so beware.

Thats why I thought if it was driven off the chain to feed a battery pack it may work better. Using a small sprocket instead of the roller should turn it slower right?
 
I tried one with a sprocket that I attached(12 teeth), my dad had one on his bike when I was a kid. Any way it worked really well for a mile then died. I spent a few hrs trying to get it to work again no luck. I didn't have it going to a battery if you have better luck I'd like to know.Mine was going to a 12 v MC head light and a cheap plastic red light. Both lights still work on a battery now.
 
Your links do not work because of forum settings designed to frustrate spammers. You are required to have a specific number of posts before your links will be functional. No, I do not know what that number is.

As for the friction generators, they really do not like speeds in excess of 12-15 mph, as their output voltage is entirely rpm dependent. I tried the small sprocket running on the chain once - the generator burnt out very quickly. If you did the math to figure the effective gear ratio of one running as intended against a tire sidewall, then put a sprocket on the generator to produce the required rpm range, it will work.

Heck, set it up to be the chain tension idler.
 
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Simon what size sprocket do you recommend? I'd give it another try if I thought I wasn't going to throw away money.
 
Measure the radius to the contact area on the sidewall from the axle, then multiply that by the classic formula: R * 6.2832 (2 pi) = C(ircumference)

That gives you the linear inches the generator wheel will run over. Calculate the generator wheel circumference, divide it into the wheel circumference, that gives you the rpm of the generator per revolution of the wheel. Calculate the revolutions of the bike wheel per mile, multiply that by 12, then multiply that number by the rpm of the generator.

Once you know the operating rpm of the generator, treat the sprocket on it as the driven sprocket in a gear ratio calculator with your engine output sprocket as the drive. That will tell you the size sprocket you'll need.

Do, please, run that output through a battery. Oh, and make your generator sprocket freewheel capable.
 
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