Re: 12V motor @ 24V

["Peter VanDerWal" <peterv@peoplepc.com>]

> Hi Pete,
>
> I have a single stage that is basically a complete hub, and have a 44
tooth
> pedal ring milled to fit over the bearing housing and bolt onto the
opposite
> side of the hub. This would give me a tad over 7:1, but I think it still
> isn't enough perhaps. Maybe it would work fine at 12 volts this way.

You're using a 6 tooth sprocket??!!?  No wonder you keep having problems
with the chain jumping off.
You need to use a 11 or 12 tooth sprocket on the motor.  Efficiency goes
south fast when you get under 12 teeth, 11 is not to bad but less than
that...
Besides anything under 10 teeth and you'll have a hard time keeping the
chain on at high chain speeds.


>
> I have a 65 tooth pedal ring made of very thick steel from an old exercise
> bike, but it weighs so much. I fear it would be best applied directly to a
> wheel, rather than on an inter-stage assembly where the inertia won't be
> given back when coasting.
>
> I'm totally confused about what you mean by the cup, and a bottom bracket.
I
> may need pictures for this one. Must be names of bike parts that I'm not
> familiar with.

You don't know what a bottom bracket is?  You really need to read a book on
bicycle maintenance, it will make your life much easier.

The bottom bracket is the part of the frame where the crank-arms (the bits
connected to the pedals) go through.

Ignoring different types of threads there are two basic types of bottom
bracket assemblies.  The older style that uses loose bearings and the newer
style that uses sealed bearings.  Either way they both thread in the same.
The parts that hold the bearings in the frame are called cups.
The most common thread used in the bottom bracket is also the same size and
pitch as the freewheel assemblies that thread onto the rear wheel (not the
cassette hubs).  If you take the freewheel apart (careful there are
approximately 19,376 tiny little bearings in there) you can remove the pawls
in there and it will freewheel in both directions.