But thats where the fun is, when rearsets are at their highest and everything, knee, shin, boot, peg, is dragging along the deck..awesome, I love it!!
I also did the calcs for gyroscopic precession as part of my engineering studies back in the 70s. Jock's description is about right but, to be a little more precise....if a body (the wheel) is rotating around an given axis (the wheel spindle) and a turning force is applied about another axis at 90deg to the first (ie the steering axis), the movement will actually occur around a third axis at 90deg to the first two (ie the longitudinal axis of the bike) and hence the bike leans over. An interesting experiment is to get an old bike wheel, hold the two ends of the spindle with your fingers (loosely) and spin the wheel. Then try and turn the wheel about a vertical axis (while keeping only a loose grip on the spindle). The wheel will bank quite strongly to one side (ie around a horizontal axis at 90deg to the spindle) and you will feel the gyroscopic precession force directly through your fingers. Another interesting experiment that I once did involved approaching a 90deg right hand bend on my trials bike while sitting on my left hand (to keep it out of the mix). My right hand was kept "open". That is to say, I gripped the throttle in the crook between my thumb and forefinger such that I could not pull on the bar at all but could only push it.....hence I could only turn the bars to the left. I used to take that right hander flat out in this manner (only 55mph on the trials bike) every day on my way home from work, despite being completely prevented from turning the bars in the "normal" direction. Now consider the point at which an imaginary line drawn though the steering axis intersects the road surface, and the also the contact patch of the front tyre on the road. Once the turn has been initiated by countersteering and the bike leans over, the contact patch of the tyre is (momentarily) no longer directly behind this point, but moves to one side or the other depending on the direction of turn. The castor effect then comes in to play, dragging the contact point back until it again lies directly behind the imaginary point descirbed earlier......which in effect creates a small turning of the bars in the "normal" direction for the turn. The distance between the imaginary point and the tyre contact patch is called "trail" and is greater for a shallow steering angle (as in a chopper style bike) and hence the effect is stronger and the steering is more stable. On a bike with a steep steering angle, the effect is weaker and hence the bike turns more easily but is less stable....perhaps like Nori Haga's bikes used to be set up. It is this castor effect which causes the bike to turn merely by leaning it over, as well as maintaining the turn once it has been initiated. It is often believed that countersteering is an "alternative" way of steering. This is incorrect. Even at walking pace, the ONLY way that steering through the bars works is in the "counter" direction....ie all steering is countersteering. Ok, if your head doesn't hurt too much by now, here's an interesting aside. I became interested in the way that we all learn this intuitively with our bodies when we first ride a two wheeler as children, but our heads don't accept it until we actually analyse it technically later on. So I began to wonder what else could be learned in this way. Therefore, when learning to play guitar, I consciously avoided any technical analysis whatsoever. It seemed to work there too. I guess its a bit like the way we all learn to sing by manipulating our vocal chords intuitively without having any idea at all what we are actually doing physically. I even once had a conversation about this with Gene Parsons (ex The Byrds), who is a biker and an engineer. (we spotted each other at a gig, as he was wearing a BSA tee shirt and I had a copy of "adventure motorcycling" stuffed in the belt of my jeans). He agreed with me that countersteering is a valid way of learning to play guitar.....!!!
At walking pace its not surely, as to go left you turn left. Whether on a u turn or a pushbike If i had my time over I wouldn't let my kids ride with stabiliser nor put the, on a trike, would be straight to two wheels so they learn this from day one
Tis true that the effect is speed dependant and increases massively at higher speeds but yes, I reckon that it still applies at walking pace. I have tried to confirm this on my pushbike, and it does seem to be the case as far as I can tell. However its not an easy test at such low speeds as you don't have anything like enough speed to maintain a stable turn following the initial countersteering input. As a result there are only milliseconds between shoving the bars to one side and taking steps to avoid the ensuing crash, leaving only an instant during which the analysis can be made. ....just my personal opinion only though. Btw, thanks for posting the link to the Twist of the Wrist video Bradders. I've been wanting to watch that for years. I've only got about 20mins into it so far, but I thought that the countersteering explanation using the kiddies bike/trike/stabilisers was excellent.
Actually, the maths says that the wheel must countersteer at any non-zero speed in order for the bike to change direction (which is why it's impossible to ride a bike that has had its steering locked). So, yes, even at walking pace it happens - it just looks to the naked eye that it doesn't and why most people think it doesn't happen until over 15mph-ish.
I knew somebody would say something like that.... OK, at walking pace, turn right to go right and see if you can without the wheel first going left 2m8s in the video. This happens at all non-zero speeds, it's just that the amount of movement of the front wheel is so small that it doesn't feel like it's happening when you're going slowly. But it must happen otherwise the bike won't turn in the intended direction. This could be demonstrated with a bike that has a ratchet steering system where the bars are only allowed to turn in one direction.
