Join Date: Jan 2004
Location: Anacortes, WA, USA
Hi Keith, a pleasure to have you here!
This is more of a theoretical question related to different chassis geometries (probably mostly the amount of trail). I know you have explored the physics of counter-steering but I've never seen this particular subject discussed elsewhere.
The following questions relate to steering a motorcycle through a tight chicane, specifically the transition from left lean to right lean. We know quicker steering motorcycles will require less counter-steering force to make the transition and that wider bars can reduce the force required (simply be providing more leverage) to steer a slower-steering motorcycle through the transition. I'm wondering two things:
1) Does a sharp counter-steering input use up some of the available traction. In other words, is it possible to countersteer so forcefully that traction is lost simply because the input was too quick?
2) If so, how does the trail of the front wheel affect this. In other words, would a slower steering motorcycle with more trail break traction easier in this situation?
This is something I've wondered about for many years. If sharp counter steering does use up some of the available traction, what is the best way to manage it? I understand the concept of riding smoothly but, as the pace picks up the transition in the middle of a tight chicane requires more force. Will a faster steering motorcycle always be able to make the transition more quickly for reasons of available traction or, given enough leverage on the bars, could a slower steering motorcycle make the transition just as quickly?
I mention trail because I suspect it may be one of the most important variables here but maybe rake, the weight of the wheels, gyroscopic forces of the engine, the wheelbase and/or other factors are too important not to discuss. And for clarity, I'm not so interested in which of these variables make the bike FEEL slower steering, rather which ones (if any) actually limit the speed of transition that is possible, assuming the rider is strong enough to countersteer as forcefully as necessary? If you have time and the inclination, I am also interested in how the orientation of the engine in the chassis might affect this, i.e., a BMW twin vs. a Ducati, especially as it relates to traction required in the middle of a chicane.
I hope these questions are not too theoretical to be of interest and that the subject matter is somewhat broad. If it's too broad feel free to discuss only the part(s) you feel are the most interesting or significant.
2002 STealTH Ducati ST4s (x2)
1985 Ducati Mille S2