Front Wheel Drive
- From: Bill Stites
Portland, OR. USA
Date: Sun, 9 Jul 2000
Subject: [hpv] Re: new FWD system
List-Id: Human Powered Vehicles Mailing List
Just so you know what's out there, take a look at the
Chameleon Trike's FWD system http://StitesDesign.com.
It uses a universal joint hub aligned over the steer
tube. Power drives thru perpendicular to the
steering axis, while the u-joint flexes to accommodate
steering. Fixed BB, no chain twist [2 separate
chains], and *no leak* of power into the steering.
I believe a lot of the classic problems of FWD have been
solved here. For those of you who had seen Roy Bird's
postings, his concepts are identical - I just pre-date
him a bit. I've recently acquired a patent [US6,062,581],
but one-ups are fine. Anyone who wants to use the
StitesHub for a personal project has my blessing, all I
ask is that due credit be given. While this FWD evolved
on a trike design, it is clearly applicable to bicycles.
The website shows a prototype ... working on a production
version now. Good luck and enjoy the process. Regards,
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Date: Mon, 31 Jul 2000
Subject: Newly completed twisting FWD
Here's some pictures of my newly converted twisting chain
front wheel drive bike. It was a moving bottom
bracket (BB) bike at one time with 12" seat height
and 14 1/2" BB height. I wanted to see if high
BB bikes produce more power and climb better so I raised
the BB to 23" (still a moving BB bike).
Raising the BB made the bike much more unstable because
the leg thrusts seemed to be magnified so rapid spinning
was out of the question (maybe Dr. Patterson could
comment as to why this happened). The bike seemed to
climb better and was faster overall because of the small
improvement in aerodynamics.
I've now converted the bike into a twisting chain FWD to
eliminate the "leg steer" effect so high rpm
spinning won't make the bike unstable. BB height now 24
1/4". Haven't done any testing yet but I'll send
some results when I've got some miles on the bike.
Date: Wed, 2 Aug 2000
There's more than 5/8" gap between the tire and
frame. It looks closer in the photo. If what
Barnett says is true that the 10" road fork deflects
approx. .20 and a 13" .45" I think I will be
OK. I did notice a skid mark on the down tube with
the moving BB incarnation with more robust fork but the
tire clearance was much smaller at about 3/8".
I don't know when it happened, maybe when I took some air
when I hit a dip going downhill at 35. But it
wasn't noticeable in braking or normal riding so it must
have been a one time episode.
The big idler is a plastic clothesline pulley. No
bearings just some grease on a 5/8" bolt. I
used the pulley previously on my wife's bike to keep the
chain from rubbing the seat and it seemed to perform ok
with little drag...now replaced with a grooved
skatewheel. There was some initial wear as the
chain settled in the groove but it seemed to hold up
alright. There is enough material to drill out the
hole to accomodate a skate bearing or bronze bushing so I
may do that at a later time. The more acute
chainline on the FWD may take a toll on the idler so I'll
have to ride it and see if it will be adequate. I
hope it will work because it is a nice big size of
4" with inside groove at 3" dia.
Thursday, 29 January 2009