🚀 go-pugleaf

In article <47r9k1$rio@cynic.portal.ca>, Curt Sampson <curt@portal.ca> wrote:
>In article <47r5nh$4mm@venice.cs.ubc.ca>,
>Andy Martin <amartin@cs.ubc.ca> wrote:
>
>>My solution to the weight vs time problem has been to add a dynamo
>>(actually two 'cause I'm running a 12 v system)
>>along with rectifier and voltage regulator.
>
>I'd be interested in more details on your dynamo system. Where did
>you get them, and how are they mounted? What do these things
>typically cost? How efficient are the rectifier and regulator?

I still consider the charging system somewhat experimental --
I'm not 100% sold yet, but here are the details:

I bought two of the standard dynamo sets that Canadian Tire sells.
They cost about $18.00 each, and contain a dynamo, a 2.5w head-lamp
and a tail lamp.  I'm looking at replacing the head-lamp bulb with
a halogen bulb as soon as a figure out a way of mounting it that won't
melt.  I'm using the tail lamps as combination tail-lamps/brake-lights,
but that's a whole other story.

The dynamos are the kind that look like the small liquor bottles that
are displayed at the cash register in the liquor store.  They operate
by a plastic knob rubbing against the sidewall of your tire.  I was
afraid that they would wear out my tire, but there are no signs of wear
on the tire so far.  I would guess I've got about 200 km on them at this
point.   What has worn badly is the plastic knob.  I'm thinking of
using some old inner tube to rubberise the knobs.

>
>One of the possible problems with a dynamo on my bike is that I've
>got 20" wheels, meaning I would spin the dynamo nearly half again
>as fast as a normal road bike would. 

I don't think that is the case.  
The knob is in contact with the rim of the tire. 
The speed at which it spins should depend only on the number of
feet of rim passing it in a given time.
This has to equal the number of feet of road passing it in the same
time, and thus should depend only on your speed.

If, on the other hand you could find a generator that somehow worked
off your hub, you would spin it faster than I could, since your wheel
has to turn faster than mine to make your bike go the same speed.

Hope this helps,
Andy