I might be wrong on this, but don't think there would be much of a worry
regarding patent infringement. What you are talking about is commonly known
as a dynomometer. These have been used since the first days of electricity,
and find it hard to believe that one could get a patent on a logical
evolution of a concept. I am working on a very similar application,
although not for an exercise bike. but FScalini did mention that this was
for personal use anyway, so it is a moot point.

In regards to the patent issue as a whole, it is highly overated in its
effectiveness to qwell others from also using your concept. This reason has
made forget about patents, I instead concentrate on  design build and get
to market as quickly as possible before all the "me Too Guys" jump aboard.

just my 2 cents

PS: I am very interested in hearing howthe completion of this project goes
for you, You might want to start off with a washing machine motor or even
an altenator from a local boneyard.
----------
> From: Tom Mariner <Tom_Mariner@EMAIL.MSN.COM>
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: exercise machine (using PIC)
> Date: Sunday, April 05, 1998 6:37 AM
>
> That, in fact is the way most modern resistance exercise devices work.
For
> a hobby, I think it's a great idea -- for commercial use, I would check
the
> tons of patents that cover this field. (I think one of the more important
> patent families is assigned to Bally.)
>
> Tom
>
> > ----------
> > > From: FScalini <FScalini@AOL.COM>
> > > To: PICLIST@MITVMA.MIT.EDU
> > > Subject: exercise machine (using PIC)
> > > Date: Saturday, April 04, 1998 10:54 PM
> > >
> > > I'm trying to make an excercise bike as a personal project using a
PIC
> for
> > the
> > > interface/control.
> > >
> > > Rather than use a friction device that makes noise, dust, and wears
> out, I
> > > though of using a DC motor connected to the pedals to create the
> variable
> > > resistance.  If I wire the motor as a generator and short circuit
it's
> > output,
> > > it should provide braking force, right?  Then I could use a PWM setup
> to
> > vary
> > > it's resistance.
> > >
> > > I'm not an electrical engineer and this is just a hobby.  Does
anybody
> see
> > any
> > > problems with the above setup.  Will a DC motor be able to handle
> something
> > > like this?  Anybody know how the gym-quality excercise bikes provide
> the
> > > variable resistance?  Any comments or suggestions will be
appreciated.
> > Thanks