The Steering Thread

[Horse]

There's a lot of really good information on steering / countersteering in the 'book' thread, so it seems a good idea to give it a thread of its own, gradually copying stuff across.

First off, a basic overview. I saved this, years ago, from the VisorDown forum. If the original author would please claim credit?

1611851326486_countersteering.png (8.07 KiB) Viewed 1232 times

If this as far as you read, it's the basic key skill and message to remember and practice.

[Rockburner]

There's a lot of really good information on steering / countersteering in the 'book', so it seems a good idea to give it a thread of its own, gradually copying stuff across.

First off, a basic overview. I saved this, years ago, from the VisorDown forum. If the original author would please claim credit?

1611851326486_countersteering.png

If this as far as you read, it's the basic key skill and message to remember and practice.

I think the only thing I'd add to that is the word 'gently'. What more do you really need to know?

[Horse]

Depends on whether you want a gentle reaction. If you want to swerve, shove firmly

[Rockburner]

Depends on whether you want a gentle reaction. If you want to swerve, shove firmly

I know that and you know that....

I was more thinking that people you show that to are generally those who don't know it already and thus shouldn't be encouraged to go around randomly shoving steering controls willy-nilly.

[Le_Fromage_Grande]

If you want to crash shove hard?

[Skub]

With good tyres and a dry road you can shove harder than you might think.

[Horse]

I can only tell what to do and give you a basic explanation of why it works.

Action
- To get the bike going left, it must lean left.
- To get the bike leaning left you must point the front wheel to the right. [Either press forward on the side that you want to turn, or pull back on the opposite side. You can either do this as a conscious, arms only, action, or as a consequence of shoulder movement]
- The quicker you want to lean (and so turn), the quicker you must press.
- The further you want to lean, the longer you hold the pressure.
- When you have achieved the lean you want, release the pressure and let the bars move - the front wheel will turn 'into' the turn.

Why
- Going in a straight line, the bike's wheels are (roughly*) following a straight line.
- Turning the bars means that the front wheel will want to head off in a different direction, but all of your momentum is still going forwards.
- If, for example, you steered the wheel to the right, that momentum will be to the left of it, pulling it over that way.
- When you release the pressure, the front wheel will turn into the turn, so both wheels roughly follow the same curved path.

* actually it's a steady series of weaves. As the bike 'falls' left, the front wheel turns left into it, that then initiates a slight right lean, which ... Not sure? Right in a straight line, hold the bars as straight ahead as possible, then make your arms rigid. See what happens. Briefly


Re precession, experiments have been done with a contra-rotating 'paired' wheel, just off the ground. No noticeable difference in steering.




Edit: it's not primarily to do with steering geometry either. Tony Foale he did extensive research on this.

https://motochassis.com/articles/experi ... -geometry/

[Horse]

And something else ... The BMW C1 is great for discussing different steering 'methods':
- it has no footrests to 'weight'
- it has no petrol tank to apply pressure against with your knees
- the rider is seatbelted in, so no body movement

That only leaves the bars and counter steering. In fact, either the rider's manual or dealer information specifically noted that riders should be taught it.

[Horse]

Here's an explanation...

Firstly, MOMENTUM (which is the product of mass x velocity) always wants to go in a straight line. If you were able to throw a cricket ball in space, it would travel in a straight line from the moment you released it. It needs a FORCE to make it change speed or direction. On earth, the ball is subject to the force of gravity which pulls it back to the ground, plus the force generated by wind resistance which slows it down. The momentum of the bike is no different - it wants to go straight on, and the rider has to input a force to make the bike change direction.

Secondly, at anything over about 10 mph, road bikes are designed to be STRAIGHT LINE STABLE - remove your hands from the bars, and they'll carry on in a straight line with no input from the rider at all, even if the front wheel hits a bump - the bars will wobble then self-correct*. If you're leaning over when you let go of the bars, the bike will snap UPRIGHT with NO INPUT from the rider. You can see that from some rather odd track crashes - when the rider parts company with the bike, but the bike bounces back upright again... it'll carry on minus rider until the speed drops down to walking pace when it finally falls over. ONLY AT WALKING PACE does the rider need to actively steer in the mild weaves which Horse is talking about. It's easy to try. Get up to 20 mph (you'll need a big empty car park or deserted straight road with a mild camber) ideally in 3rd gear if the bike will do it so you don't get too much engine braking, then simply lift your hands just off the bars. The bike will roll straight until the speed drops down to about 10 mph, then the bike will start to wander, and finally (it's about 6-7 mph on my bikes), it'll threaten to fall over at which point you have to actively steer it. (* Which should tell you most of the instability in a bike travelling at any speed is induced by the rider.)

So the bike's stability in a straight line is a combination of its design and momentum.

Thirdly, momentum acts on the combined Centre of Mass (cCoM) of bike and rider. Very roughly speaking, it's usually about where the back of the tank meets the front of the seat - that means it is around 750 - 800 mm ABOVE the surface of the road.

But - fourthly - the force we apply to get a bike to CHANGE DIRECTION necessarily happens where the tyre touches the road SURFACE.

And this is where it gets interesting.

Moving in a straight line, the cCoM is directly above the line connecting the points where the tyres touch the surface - the bike's mass is balanced directly over the points of contact with the ground.

Imagine what would happen if you stood by a perfectly-balanced bike and pulled a rug out from under the front wheel. If you were standing to the right of the machine, the front wheel would be pulled to the right - and the bike would topple left.

When we steer the front wheel to point to the RIGHT, the force acts on the wheel to pull it to the right - and through it, the forks and the rest of the bike - works at ground level. The mass of the bike meanwhile - acting through the cCoM at the height of the seat - tries to go straight on.

You should be able to see what happens next. With the front wheel steering to the right, the cCoM is no longer directly above the line connecting the wheels, and the bike leans to the left.

Effectively, when we counter-steer, we're pulling the front wheel out from under the cCoM to the right, the moving bike actually topples to the LEFT.

You can try this without riding the bike. Try walking along by placing one foot directly in front of the other - this means you're balancing just like the bike and you should be able to stay upright with no big problem because your CoM is directly above your feet. Now take one more pace but place your left foot to the RIGHT of your other foot - you'll find you lose your balance and your body topples LEFT! It's analogous to the front wheel steering out from under the bike, with the bike toppling the other way.

That's enough to explain the INITIATION of counter-steering - there's actually a bit more to know about what's happening mid-corner and why the bike wants to straighten up again, but the info above is enough to get the bike to ROLL off the vertical and to generate a LEAN angle to get you round a bend.

Although people love to do demos with spinning bicycle wheels to 'prove' that the front wheel is a gyroscope (it is) and because you're forcing the gyroscope to lean it steers the bike (it doesn't - gyroscopic precession is insignificant and IIRC Tony Foale calculated it was around 5% of the forces operating on the front wheel), it's almost entirely down to straight-line momentum, and the steered wheel causing the bike to topple sideways.

[Rockburner]

And something else ... The BMW C1 is great for discussing different steering 'methods':
- it has no footrests to 'weight'
- it has no petrol tank to apply pressure against with your knees
- the rider is seatbelted in, so no body movement

That only leaves the bars and counter steering. In fact, either the rider's manual or dealer information specifically noted that riders should be taught it.

I really enjoyed the C1 I rode around on at Longcross. Nice tight turning circle IIRC.

[Le_Fromage_Grande]

With good tyres and a dry road you can shove harder than you might think.

It's not something I consciously think about, but I notice that I'm counter steering on dirt more than I do on tarmac.

[Horse]

Depends on whether you want a gentle reaction. If you want to swerve, shove firmly

I know that and you know that....

I was more thinking that people you show that to are generally those who don't know it already and thus shouldn't be encouraged to go around randomly shoving steering controls willy-nilly.

Fair enough

Biggest, most consistent (across many riders) problems that I've seen are:

- a very brief 'wiggle' of the bars; the bike just shimmies, the rider doesn't have a chance to feel what's happening

- the rider doesn't believe it will work, so you see combinations of rigid arms leaning the opposite way, all sorts

- there was a third but, while one finger typing, I've forgotten...

- actually, I've thought of the fourth .... closing the throttle

[Horse]

With good tyres and a dry road you can shove harder than you might think.

It's not something I consciously think about, but I notice that I'm counter steering on dirt more than I do on tarmac.

I saw an article recently. Someone computer modelling motorcycle handling. He'd contacted one of the well-known US racers and asked how he controlled a sliding bike? The answer was, simply, counter-steering.

The technical answer? See the Tony Foale link, he covers it.

[Dodgy69]

If you just lean off the bike, would it counter steering itself. ???

[The Spin Doctor]

If you just lean off the bike, would it counter steering itself. ???

No.

Not in the way you're expecting, anyway.

You CAN steer a bike by body shifting (no matter what Keith Code claims) and there's a video somewhere of me doing a mild hands-off slalom in the car park at Castle Coombe on a Triumph I hadn't ridden until 30 seconds earlier.

But a bit of Newtonian physics to think about - action and REaction. If you lean one way, the bike leans the other.

[MingtheMerciless]

Big fan of Mr Code here, read his books when I was a new rider. I think I counter steer every time. If you want a relatively penalty free practice take your MTB out and practice with that (with the caveat not to drop your shoulder and weight into the corner as that loads the front tyre too much, this from Tony Doyle the Jedi Master of MTB tuition who on my training day spotted I'd ridden big motorbikes within a few corners).

[Horse]

The only time I've ever had to "consciously input" CS is when at speed, and then not very often. Maybe this is why it is cbt exempt.

'Conscious' is the key aspect. For many riders, they won't ever need to consciously 'steer'. Whether they counter-steer without thought, or 'just lean' - and accidentally apply pressure to the bars, doesn't matter, they succeed.

But the problem comes for those riders who when under pressure - tightening bend, swerving - don't have that instinctive reaction. Then they 'steer'. And can't understand why the bike won't do what they want and expect.

[Horse]

First off, head for the gaps. Works on the road too: rather than look at a pothole you need to avoid, look at the bit of good tarmac. As soon as you're heading that way, look ahead and choose the next point, and repeat.

If you look 50cm to the side of the cone, then ride over that surface, you won't- can't -collide with the cone.

'How' you use it for 8 & U isn't a simple answer. At slower speeds the amount of pressure (and so front wheel out tracking) is so minimal that you will hardly notice it. In fact, as I said earlier, by just moving your shoulders slightly sideways and 'leaning' from side to side you will accidentally apply enough pressure to weave through a slalom.

For a U, the initiation of the turn will be a single press. Then the front wheel will almost 'flop' into the turn (and so why you need the relaxed 'egg' grip, to allow this) and you need to be looking through the U back the opposite direction- where you want to be - and driving it there.

[Horse]

Visualisation is a fantastic.

For machine control and head turns, look on YouTube for Jerry 'Motorman' Palladino.

Here's another fun video


[/quote]

I find it unhelpful to concern myself with counter-steering for manoeuvres at a walking-pace like the U-turn. I'm more focused on looking where I want to go!

One of the skills many riders don't have is control over stopping. Might sound daft, but ask a few riders to first stop with one foot down, then again with the other - but keeping both feet up until stopped or just about.

Often, riders don't decide, they just let the bike slow and wobble, or wave a leg about to encourage it to lean, or plonk both feet down.

A very gentle counter-steer just as you stop will lean the bike. Probably irrelevant on a 125, but stopping a tall bike on a camber? See at 0:38 in the SF video.


As I said, the movement of the bars for a slalom is almost imperceptible, mid-way the front wheel will already probably be tracking in the direction of the counter-steer, it just needs a small amount extra.

You might not concern yourself with it for a U, but without it how does the bike start to turn? Problems come when riders consciously try to direct steer.

You'll also need some drive to stop the bike toppling, that's part of the 'package' too.

[Cousin Jack]

If you just lean off the bike, would it counter steering itself. ???

Yes. As a 14 year old I was ace at riding a push bike around corners no hands. I am sure most 14 year olds today can do the same.

Lean over, steering 'flops' over*, and round the corner it goes. I would imagine a motorbike would work the same, but it would be a hell of a sight less responsive because of the weight.

*IIRC (I haven't tried this for almost 60 years) the steering flops the opposite way to your lean, and you then have to reverse your lean off so it continues to track around the bend. Sort of countersteering by weight shift.