Posted by stu on February 17, 2010, 3:03 am
Then what technically is it? unless it's a small wheeled bike, then its not
likely to have even 4 to 1, better count those teeth. Around 48 on the
front(maybe more for a road bike), 14 on the back(maybe 11). If it is a
small wheeled bike it might be as high as 56/9.
I don't see the amount of "wrap" on the small sprocket as a problem. What
might be a problem is the amount of tension on the chain if the OP wants to
get much more than 200W, and even that might be to much. Even to get to
480rpm he needs 40 to 1.
Posted by sno on February 17, 2010, 3:56 am
On 2/16/2010 10:03 PM, stu wrote:
I do not remember where I saw it, was somewhere on the web....instead of
gears used a auto tire rubbing against a large wheel to increase
rpm....then another smaller tire attached to the generator shaft rubbing
against the auto tire...to get further increase...
had springs on each side of tires to keep them together and help
preventing slipping....hope this makes sense.....worked just like gears
but no teeth.....
thank you for listening to my thoughts....have fun....sno
Correct Scientific Terminology:
Hypothesis - a guess as to why or how something occurs
Theory - a hypothesis that has been checked by enough experiments
to be generally assumed to be true.
Law - a hypothesis that has been checked by enough experiments
in enough different ways that it is assumed to be truer then a theory.
Note: nothing is proven in science, things are assumed to be true.
Posted by vaughn on February 17, 2010, 1:40 pm
Same principle as an old-time bicycle headlight generator.
(Amazon.com product link shortened)
...or an old mechanical Harley Davidson motorcycle siren:
Posted by Bob F on February 17, 2010, 6:10 pm
Considering the size of "pulley" the OP was talking about, a friction wheel
makes some sense. Spring mount the generator to allow for minor
out-of-roundness. The major issue would be having enough friction to avoid
slipage at what might be significant torque.
Posted by harry on February 17, 2010, 6:54 pm
And keeping it dry. There would be lots of losses from friction.
Hey, how about using a "hub dynamo" from a pedal bike?
It would seem to solve all the problems at one go!
You could mount it with no gearing/belts/chains at all.