gam@proper.UUCP (08/13/84)
@ My other question: OK, you are zipping down this two-lane highway and you see this big logging truck coming up the other lane. You move to the right (right?) and prepare for the hurricane. It passes with a moderate zephyr but no gale force winds. Have you noticed that certain truck SHAPES may affect the air currents you run into as they go by? I haven't noticed this much myself, but a friend says that logging trucks and propane (or other gas) trucks seem to create less hazards for motorcyclists. Do you agree with this? Do you have your own theory on this matter? [Is everyone off on vacation or what?] -- Gordon A. Moffett { hplabs!nsc, decvax!sun!amd, ihnp4!dual } !proper!gam
marauder@fluke.UUCP (Bill Landsborough) (08/15/84)
You are right about shapes of the trucks and the turbulance they create. I have learned that the worst are big, tall, and square corners all the way around, especially the back of the trailer. The front first creates a high pressure area which pushes everything away from it. Then the back, being big and square, creates a large vacuum area which sucks everything back into it. The real condition which sets up the "big blast" when you are riding by is when the wind is blowing from your left side and the oncoming truck breaks that wind with a monsterous blast of pressure then vacuum. Your riding along leaning slightly to your left against the normal crosswind when the truck goes by and triples the velocity. You counteract by leaning harder to the left just as the truck gets by and the vacuum pulls you violently to the left. It becomes tough to stay in your planned lane when the cross wind is around 30mph and the trucks speed is at 70! This is real common on two lane highways in the deserts. Oh well... just tuck down and hang on!
gt@hplvla.UUCP (gt) (08/16/84)
<<< LEAN WHEN YOU TURN >>> maurader is right... especially about the prevailing winds. I have noticed that identical trucks will cause everything from almost no disturbance to stomach churning excitement depending on the prevailing winds. One nice thing about doing most of your riding above 5000 feet is that the air is so much thinner. George Tatge ihnp4!hpfcla!hplvla!gt Today's safety tip: When riding with no hands, always keep your foot ready on the brake.
an@hou2h.UUCP (A.NGUYEN) (08/16/84)
- Riding position has a lot to do with it. If you sit up right, you are presenting a nice and big sail to the wind to blow on. Ditto large fairings. Ditto large bikes, though their longer wheelbase offset the effect somewhat. I've gone places a lot on a Honda 360 (54" wheelbase) and a Kaw 550 (55" wheelbase) -- both had lower than stock handlebars (1" rise for the 360 and 4" drop for the 550). Neither had Windjammers or anything of that sort. Both had very good stability in crosswinds and wakes of large trucks. Au
kar@ritcv.UUCP (Kenneth A. Reek) (08/18/84)
The prevailing wind direction has a lot to do with how much turbulence you will feel after a truck goes by in the other lane, regardless of the shape of the truck. -- Ken Reek, Rochester Institute of Technology {allegra,seismo}!rochester!ritcv!kar