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 <hpv.ihpva.org>
  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, Bill
  
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  From: Cyril
  Date: Mon, 31 Jul 2000
  Subject: Newly completed twisting FWD
  
  http://albums.photopoint.com/j/AlbumList?u=899762&Auth=false
  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.

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Thursday, 29 January 2009