looks to me like some one caught up in the mumbo jumbo about countersteering over egging a point about countersteering the movement at that speed appears to me in my humble opinion to be completely over the top.....avoidable and unecessary!
Isnt the debate NOT about starting a turn but what happens IN the turn. Ie the front tracks away from the corner while on its side at speed, whereas at walking pace it goes with the turn. Once the bike is turned, if it starts to track into, not away from, the corner, isn't that where it runs wide, hence the throttle is so key to a good tight exit?
It's unavoidable. If the bike turns, the wheel (however undetectably to the rider) must have momentarily turned in the opposite direction otherwise the bike couldn't have turned.
er no......not at walking pace except in a contrived video.... So the answer to the question still stands as the rider...
Gyroscopic effect only works to initiate a turn when the wheels are spinning fast enough to generate enough force. Approximately 14mph for most bikes. Below that speed the bike will follow where the front wheel points, when you are maneuvering into a parking space at slow speeds you dont countersteer do you...
The rider doesn't (consciously), but the wheel has to otherwise the bike won't turn the way you point it. A bike with it's steering locked in one direction can't be ridden - no matter how slowly. Have a look at some of those videos of US police officers going slowly (<5mph) inside cone circles on Harleys and look at the front wheel. Even though the majority of the time the wheel is facing in the direction of travel, it always steers the other way at certain points. The physics dictates that it must.
Koen,i have loved reading your build thread,and your riding ability is far better than mine will ever be,but you seem to be beating yourself up striving for quicker lap times,asking on a general forum for kind of advice you require is always going to get conflicting replies,i think you need to talk to or seek help from someone who can really help you achieve your goal,maybe pay for a one to one session with one of the racers on your trackdays,could be the best money you spend ?.
I'm sure he gets that, and is having lots of realtime advice. Tbh its nice to have a debate/discussion on something related to bikes for a change
Here's my take on this. Counter steering is what makes the bike lean over, no other way to do it effectively. The Twist of the Wrist video makes this quite obvious with their bike with the fixed handlebars. But once lent over the front wheel is turned in the direction of the turn. You can see this with their bike with the steering pointer. The pointer is always 1 mark off centre during the turn. If you look at still pics of turning bikes you will also see that the front wheel is turned in the direction of the turn. Not much I grant you but then the radius of the turn is quite large so only a small amount is required. So the bike turns because the front wheel is turned in the direction of the turn, just like everything else on wheels, the only difference being that it has to be lent over before it can start the turn.
Countersteering works at all speeds, although its strength is still speed dependant. Try riding your pushbike one handed at very low speed, with that hand held open so it can only push and not pull on the bars (as I described earlier in my trials bike experiment). If you're using say, the right hand you will only be able to turn right, not left. Although as soon as this happens, other bodily reactions will automatically and instinctively be employed to avoid crashing, thus masking the countersteering effect. It is commonly misquoted that countersteering involves actually turning in the wrong direction initially, followed by a countersteering reaction to this initial movement of the steering.. Not strictly true in my opinion. What happens is that countersteering force (not actual movement, just the force), is applied to the system and this immediately and directly results in a countersteering effect. There is no initial movement of the steering in the wrong direction, only the force which would be expected to produce that result.....but doesn't. In other words, the countersteering effect is in response to the force producing it, rather than to any actual movement of the steering. Its a bit like looking into a mirror while trying to manipulate scissors to trim your sideburns....the scissors always end up moving in a direction that you weren't expecting, until you recalibrate your brain to account for the reversal effect of the mirror. Incidentally, countersteering also works to bring the bike out of a turn as well as to initiate one. An applied force pushing on the outside bar will lift the bike back upright. Of course a cornering motorcycle is quite a complex system with many different individual physical effects coming into play at the same time, all of which contribute towards the end result. So body lean, peg weighting, throttle control etc will all have an effect on the overall situation, as will the geometry of the bike, castor angles, tyre profiles, weight distribution etc. Its difficult to analyse the full picture, and ultimately it comes down to the "feel" of the rider. But, as with the scientific method in general, a better understanding the physics of each individual facet is nevertheless helpful in building a better understanding of the system as a whole. Hope some of that helps. And doesn't make me sound too geeky about it. Its just that, as a biker and also having started out as an engineer, I've been thinking about all of this for over 40yrs, so I'm bound to have a few insights to offer by now, eh ? As always, I believe the above to be correct otherwise I would refrain from posting it, but whether anyone accepts it or not is entirely optional.
You're correct Bradders. I had actually spotted that already to be honest, and didn't particularly understand why at the time, but I posted anyway in the hope of prompting further discussion (or even just to force me into thinking about it a little more deeply myself) and ultimately arriving at some sort of explanation. I stand by my earlier comments, but perhaps I could have chosen my words a little more carefully. What I was trying to say is that countersteering is a consequence of gyroscopic precession, which works in the way I described when it operates in isolation. But, as I said before, a cornering motorcycle is a complex system and many other factors come into play. Having considered it further, I've come up with the following.... The countersteering input which the rider puts through the bars operates about the steering axis, which is not vertical but inclined at 20 odd degrees. Thus there is a component of this input which acts around a truly vertical axis and causes gyroscopic precession of the front wheel, and another which does not, and which therefore does not cause the same gyroscopic reaction. I can't quite get my head around exactly what this other component does, but I suspect that it somehow muddies the waters and leads to the initial turning in the "wrong" direction. This would cause the contact patch of the front tyre to shift sideways such that it no longer lies directly in line with the bike, whererupon the castor effect will drag it back in line again, thus correcting the initial turning of the wheel in the wrong direction. Does that sound like it makes some kind of sense ? Even if it does though, I strongly suspect that it isn't the full explanation, as the system is a complex one. But I'm definitely getting into the realm of thinking (waffling ?) out loud here, so take from it what you will.
Watch a speedway rider.......... The wheel is turned opposite direction to the bend....... The bike is leaning over because of that...... And most of the time the rider is as near as dammit standing upright rather than leaning.....or at least his bum isn't always in the saddle.....
Great example. Isn't that the same as a motorcrosser tho, where they only really steer with the rear as opposed to a tarmac rider who also needs the front to track closer and have far more grip, hence they push the bike down rather than hold the bike up
I dunno bradders.... What I do know is that when I tried grasstrack (same method riding as speedway, just about) that I kept wanting to hit the front brake which didn't exist, so I never went very fast....... ......but when I had a go on a motocross bike, the front brake did exist, and so did the mud which I found myself in several times. But back to speedway riders.........just study them.........even though the speeds aren't the same as road race speeds (perhaps); it's still bl**dy quick and nearly the same speed all the way round the track.... ....watch them as they hit just before the start of the bend............they literally fling the bike into the corner by the countersteer move and stop it from falling over with their foot / leg, but there isn't what I would call a great deal of lean in the body, only the bike..... ......could be that the low CoG makes that difference, but I have also seen the rider out of the saddle with one foot in the shale and the other foot on the rest, so most of his weight is on the outside of the bike because the other leg would be broken otherwise...... ....therefore as you say, throttle control must be crucial to keeping the bike at the right angle and in the right direction..
Ah but the speedway/ motocross thing is an entirely different kettle of fish. There the steering in the opposite direction is to control/balance the massive drift at the rear. Though I agree that they do seem to use heavy countersteering to drop the bike into the turn in the first place. Along with rear wheel braking to provoke the drift, I imagine......I dunno, I'm too cowardly to try it myself. But the observed turning of the front wheel is down to steering into the drift, I reckon. This is sometimes mistakenly called countersteering, but it has nothing to do with gyroscopic precession. In fact, a constant turn of the wheel around the bend will not cause gyroscopic precession at all...its a change in the amount of turn which causes it.....or rather its the force which tries to produce such a change. Ok, moving a little further along.... I reckon its still possible for the drifting speedway rider to use countersteering within the turn. All speedway turns are lefties so by pushing say the left bar, the bike would drop further, and by pushing the right it would lift. But this would then in turn affect the amount that the rear wheel was able to drift, so a further adjustment (to steering and/or throttle) would be needed to balance that out. And this might well be a constant juggling act all around the turn, particularly if certain bits were a bit grippier than others. Again, I'm thinking on the hoof here........no guarantees that it makes sense, though it does seem reasonable to me.
