From: "Greg Peek" To: Date: Thu, 10 Aug 2000 15:13:37 -0600 charset="iso-8859-1" Subject: [hpv] RE: CV JOINT VS U-JOINT >Wonder what Greg Peek over at Longbikes would have to say ... he's been >working improvements into u-joint steering. Glad you ask! I picked up on the u-joint where Dick Ryan left off. I will summarize what I have been through and experienced without going into a lengthy discussion. Anyone wanting more detail may give me a call. The size and quality of the U-joint is critical. DO NOT use something out of your tool box. DO NOT use a commercial "pin and block" style U- joint. These do not have enough thickness on the side of the yolk nor large enough pin diameters to handle the load that will be applied. They will spread open and cause slop in the steering. We finally developed an aluminum U-joint body and found a large diameter needle bearing to put into it. This is beefy enough to handle the torsional loads of even a Duplex tandem. Steering shaft support. Necessary and must be close enough to the handle bar to prevent shaft flex, yet far enough from the handle bar to allow you to mount the bike. The attachment of the support to the frame will take a lot more load than I ever thought possible. This must be heavy duty on a tandem and not as heavy duty on an LWB single. Steering quickness. This is the big one. A U-Joint steering bike will have quick steering!!!! You could slow it down with gear reduction, either gears or pulley and cable. I rejected both of these due to cost, complication, weight and visual clutter. A U-Joint has limited leverage to affect the "steering ratio", that is the radius of the handle bar, approximately one foot radius. A LWB with ASS tiller will have a much longer radius, the effective length from the steering tube to the top of the handle bar, perhaps 2 - 4 feet. With this simple comparison the U-Joint will have steering that is 2 - 4 times faster / quicker that a tiller bar. If you like quick, twitchy steering or can relax so that you have virtually no input starting or going straight then maybe U-Joint steering is for you. I think now that it is not for most people. We had one Duplex with U-Joint go to a short 5'5" captain who probably for a number of reasons could get the bike started without great difficulty. He and his dealer changed it to tiller bars, and he loves the bike. We have made on last change to the steering setup. The Duplex pictured on our home page has been changed to take the steering support shaft through the top tube down into the diagonal for increased rigidity. At this point I believe that we have developed the steering to a reliable point, the parts hold up, I can't change the steering ratio and I have no intention of putting any further effort into U-Joint development or refinement. If you care to discuss it further, contact me. If you would like to build your own U-Joint system, I have parts and will be happy to sell them to anyone who wants them (they are not cheap however). Greg Peek Longbikes 8160 Blakeland Dr. Unit D Littleton, CO 80125 1-877-TANDEMS http://www.tandembike.com e-mail: greg@tandembike.com