QuestionMr. Hahn,
I am in the process of research and design for a 3 wheeled vehicle. The vehicle will have 2 wheels in the front (Rack and Pinion) and a single wheel in the rear. The vehicle will be very similar to the as now well known vehicle on the Internet as the “T-Rex”, which is made in Canada. I was doing research on the internet for the design and came across your response (http://en.allexperts.com/q/Motorcycle-Safety-Driveability-790/Car-tire-motorcycl...) to the question of replacing a Motorcycle rear tire with a car tire. If you can locate a website of the T-Rex (http://www.gizmag.com/go/3535/) you will see that they are using two shocks and a car tire. I think you are right in the fact that a single rear car tire would require 2 shocks. The stress produced with a single swing arm and a Mono shock set up might be too much stress using a car tire going around corners. But here are my questions;
1. Would there be too much stress in this same set up as the T-Rex if a Mono shock and single swing arm was used? I tend to think so, but I am asking for an expert opinion.
2. Do Motorcycles have adjustable ride heights on the Valkyries and VLX’s you mention? I wish to use 16” rims and tires up front. Do you think this is too high?
3. I am assuming the larger bikes will also engine sized needed for my requirements (1200cc and higher)
4. Do Valkyries and VLX’s come with a transmission that has a reverse?
Thank you for your help in this. I look forward to hearing from you.
AnswerPlease bear in mind that I am a safety-minded motorcycle enthusiast, and not an engineer!
1. My assertion that a car tire on a motorcycle would need two shocks was based on the idea that the bike needed to lean to turn. Twisting forces from the tire itself would be added as the tire constantly rode up on its edge. (I now see that the bearings would take an awful lot of this load...I hadn't thought of those before. And I have to imagine that the tire would run rather hot....)
If the rear tire on your vehicle will not lean when turning, you may be able to get away with a monoshock and swing arm. However, with a heavy vehicle, a monoshock will get sacked out rather quickly. Really, even for a (relatively) light weight motorcycle, the shock should be R&R'd every 25,000 miles at least. And when turning, my guess is that there is still some degree of side force (centripetal?)on the swingarm, bushings, and bearings, so dual shocks may still be best.
2. 16s are probably just fine. The ride height of those bikes is not adjustable on a "day-to-day" basis, but the ride height can definitely be adjusted. I think the term for the parts that you use to change rear ride height is called a "dogbone," which, I believe, attaches from the swingarm to the rear shock. Different shock springs or a longer/shorter shock would also change the ride height. The front ride height is changed by raising or lowering the forks in the triples, pretty simple. (Note that these changes also change the overall geometry of the bike and affects handling.) There is a very good chapter on suspension setup and geometry in Kent Larson's Track Day Handbook, the chapter was written in part by Max McAllister of Traxxion Dynamics' fame.
3. Yep, go with the larger engines: 1100cc+ for an inline four and 1600cc+ for a twin. If you're looking for a reverse gear consider a Gold Wing 1500 or 1800, I think they both have reverse.
4. Some bikes (notably Gold Wing) do, but they're not the traditional reverse like in a car. They're a very short reverse gear turned by the starter, not the motor/clutch. Valkyries and VLXs do not have reverse to my knowledge. The Valkyrie might, as it borrows heavily from the Gold Wing, but I've never heard of it.
Good luck with your project!
Pat
