In article <1qjn7i$d0i@sixgun.East.Sun.COM> egreen@east.sun.com writes: >In article 26051@rd.hydro.on.ca, jlevine@rd.hydro.on.ca (Jody Levine) writes: >>In article <1qc529$c1r@sixgun.East.Sun.COM> egreen@east.sun.com writes: > >>>Single-track snow vehicles with front skis, and snow skis attached to >>>skiers' legs, deform the surface of the snow, creating their own bank. >>>Ice skates alter the phase of the ice, and also "carve" out their own >>>tracks. >>So what?  > >So they have bugger all to do with motorcycles.  Hence, any apparent >similarity in handling characteristics may, or may *not* be analagous >in its underlying physics to that behind motorcycle handling >characteristics.  OK, as one last attempt, I'll take a different tack.  We all seem to be in agreement that there are two explanations for why one can use the handlebars to lean a moving motorcycle. The question is, is one of the effect dominant, and which one is it? The idea would be to design an experiment which would seaprate the two characteristics, and see which effect produces a similar result to the one with which those of us who have bikes are familiar.  Let's look at the one that, so far, has sparked no controversy on its own, gyroscopic precession. To examine this alone, we would have to get rid of the contact patch effect, by not allowing the contact patches to transmit any force. The wheels and steering mechanism would have to remain, and be attached to a vehicle with about the same weight as a bike, through suspension (so that the wheels transmit forces to the bike the same way) similar to a bikes. An experiment would be to ride a bike along  a dry road to get moving and to get the wheels spinning, then change  surfaces to something that won't transmit forces through the contact  patches, and try a steering manoeuvre to see if the bike leans. It  probably would, since some of us know how easy it is to fall down on ice,  but we wouldn't get a good idea of how well or what it feels like  because, without the contact patches, we can't turn.  Maybe there's a  better way. Besides, even ice doesn't get rid of the contact patch forces altogether, so we'd have to find a really frictionless surface. You'd have to try it again with the wheels locked to really know if it was the rotation that did it.  Looking at the contact-patch effect only, however, is fairly simple. Now we have to find a vehicle that gets the about the same magnitude and direction of cantact patch forces as a motorcycle, and transmits them about the same way to the vehicle, but without rotating wheels. How it gets the contact patch forces is irrelevant, we're just looking for something that has contact patches that can go straight and not sideways, and skis or skates would do fine. I don't know of any snow-ski or skate bikes, but up here we have the Suzuki Wetbike that is arranged like a motorcycle but has fat water skis where there should be wheels. I think the propellor is in front of the rear ski, or something like that, but we could try it at a coast to get rid of most of its effect. Now I admit that this is second hand info (although I'd love to try one of these), but the review in the local cycle rag and a guy in a bike shop that sells them both say that this machine handles very much like a motorcycle, in that you countersteer it to turn. So we have contact patches that transmit similar forces to a bike's, a similar suspension arrangement, and no gyroscopes, but we do have countersteering.  Conclusion: you don't need gyroscopes to countersteer vehicles that have motorcycle-like contact patch arrangements. We still don't know what real effect the gyroscopes have when they're there, but from my observations of how handlebar angle, force, etc. relate to steering in general, I'm  willing to bet that they're not the dominant factor in countersteering.   If you don't like this conclusion, then don't accept it, but my motorcycle's behaviour is consistent with it. If someone can prove otherwise, go ahead.