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Tightening bend – slow down or lean over more?

It’s the quandary that every rider bar none will find themselves in sooner or later, and unless we ride in the wilds of Nevada where the roads are straight for fifty miles at a time or we never venture off the UK’s motorway network, then the chances are we’ll meet a decreasing radius corner of some shape or form every few minutes rather than every few hours.

So how do we deal with a bend that the vanishing point is telling us is tightening up?

Well, as I posted just a few days ago when reviewing the IAM’s handbook:

“By far the simplest way to deal with a tightening corner (assuming the rider has gone in with a degree of caution, aware that any corner can tighten) is to maintain vehicle stability by adjusting lean angle as the limit point moves towards us. That way we avoid throttling off, and thus avoid destabilising the bike mid-corner. Keith Code (and the California Superbike School) emphasise just this point with their throttle control exercises, and it’s what we should be teaching riders to do on the road.

“And if we’re going in too fast, arguably we should have used the brakes positively and upright before we got there.

“In any case, we should go into a corner with learn angle in hand because we should be aware that the ‘limit point’ is just that – it’s the furthest limit to how far we can see. Just as a snapshot gives us no clue what happens in the future, so the limit point can tell us nothing about how the bend develops out of sight. Which happens to be why we have road signs – to warn off hazards like tightening bends that cannot be detected simply by looking.”

However, this explanation didn’t find favour with Ken Haylock, who wrote to me a couple of days back and said:

“Sorry, I’ve tried to ignore this, and I’ve tried to see what you are getting at, but… umm… I just don’t. You criticise the book for saying:

“In short, the advice given is if the limit point moves towards you, you may need to slow down.”

Well… call me slow on the uptake, but I really cannot for the life of me see any other way of safely dealing with a tightening unknown bend than to slow down when you discover that it is tightening. The alternative is either to tootle up to it at a speed that assumes that it might tighten up into a 180 degree hairpin, even if it appears to be a fast kink on approach. Or you could just say “Well, I thought 70mph was appropriate when I looked at the entry to the apparently gentle bend, now I see that the line of telegraph poles I partially relied upon for my initial assessment is actually going across a field and the bend is actually tightening a bit, but slowing down is very bad so I’ll just see if I can get round anyway without slowing down… and now I’m still doing 80mph with the left hand peg down and the exhaust starting to scrape as the road appears to be further tightening into a nasty double S bend that cannot be safely negotiated at more than 25 miles per hour, and Oh Dear Mummy. Still, at least I didn’t slow down when the limit point started to move towards me… {BANG!!!}.”

Clearly rolling off the throttle loads the front tyre, and slamming the throttle shut in first on a big twin, let alone braking, loads it a very great deal, but for my money, if you approach a bend at a speed where you judge that you can stop on your own side of the road in the distance you can see to be clear (i.e. before the limit point) then you should already have factored in your assessment of the available grip. Shiny tarmac in the rain? Long stopping distance, lower corner approach and entry speeds. Sometimes a lot lower. Shell-grip on a sunny day? Faster… all meaning that whatever the conditions, you have room to adjust speed gently at the earliest opportunity, so you can just smoothly roll off a little, and thus smoothly load the front a little, as the corner tightens.

In the rare event that the corner suddenly changes character from fast sweeper to hairpin mid corner, assuming there were no signs to forewarn you of this eventuality, then as soon as the limit point starts rushing towards you almost as fast as you are going, you have the opportunity to stand the bike up, brake as hard as you like in a straight line, and then drop back into the corner at the appropriate speed. Ditto if it is so horrible and slippery that you don’t fancy loading the front at all even a little bit and you would like to slow down even more for the next part of a tightening corner. When the corner gets tight and nadgery enough or slippery enough and the speeds get low enough, for me the choice becomes between treating any given corner as either an exercise in bolt-upright slow control, or squaring it off into a right-angle.

But I can’t see how I’d live as long as a fortnight if I *didn’t* slow down when the limit point moved towards me. Try that approach on the A4069 Black Mountain in Wales or the Sugarloaf on the A483 or any number of other places where the topography governed the road layout, and you’ll get about ten seconds of glorious air-time to think about what went wrong before you hit the ground :-/.”

I rather get the impression Ken doesn’t agree with me.

So let’s try to explain, in a little more detail, why I think the advice to roll off the throttle when confronted with a bend that the limit point suggests is tightening is wrong.

First and foremost, it doesn’t help machine stability. Keith Code is very positive about this – we should be able to role on the throttle from the beginning of the bend to the end in one smooth action.

Specifically, if we’re turning, then loading the front end with a closed throttle doesn’t help the machine steer. We’re not talking racetrack geometry here, but bikes designed for the road, wearing road profile rubber and ridden by road riders – don’t believe everything you read in Performance Bikes about bikes turning better hard on the brakes!

It’s also worth pointing out that tyres don’t stick to the road like glue – in fact, they drift. It’s called tyre slip. Paired tyres are designed so that when cornering on gentle throttle the rear slip angle exceeds the front; in car terms, the bike oversteers slightly. It’s very subtle and most riders will never feel it.

They’ll never feel it, that is, right up to the moment they shut the throttle mid-corner on a greasy surface as the corner tightens slightly!

At that moment, the nice ‘planted’ feel of the front tyre will vanish as the slip angles reverse and the slip angle of the front exceeds the rear. The result is a nervous, edgy feel from the front end, as the bike begins to understeer.

It may even feel like the front tyre is on the brink of sliding out from under, and although it’s very unlikely to let go just from shutting the throttle in point of fact I have crashed at exactly the point of throttle transition from ‘on’ to ‘off’ without doing anything else. The “good stability” solution is to keep the throttle open, keep the slip angle at the rear exceeding that of the front, have some confidence in the tyres, and lean a little more.

That’s at least part of the explanation for Keith Code’s teaching and why for minor adjustments of radius around complexes of corners it’s better to use lean angle and maintain a steady speed, rather than opening and closing the throttle to speed up and slow down to maintain a constant lean angle.

OK, I’m presupposing that the firstly the vanishing point shows only minor changes of radius, and secondly that we’re not using huge lean angles but have plenty of lean (and grip!) in hand, but that goes hand in hand with the advice that we should be able to “stop in the distance we can see to be clear on our side of the road” . If we’re obeying that simple rule, it means that any minor change of radius really CAN be dealt with by changing lean angle rather than the speed of the machine.

So how do we deal with a hairpin we find just round a bend we’ve approached at 70mph, the problem Ken poses?

Well, the obvious objection is that is it’s very rare that we ride into a bend at 70 and find a hairpin on the other side of it without some inkling that we’re riding into trouble! Not to say it’s impossible, but it’s not common and hairpins generally come with some warning from the terrain. The very locations that Ken mentions give us a clue! And even if we didn’t take that one on board, we WILL have spotted the road sign warning us of a sharp bend ahead, won’t we?

And based on those warnings we’ll have applied the brakes in good time to “tootle up to it at a speed that assumes that it might tighten up into a 180 degree hairpin”, won’t we?

Nevertheless, we all get it wrong. So let’s for a moment say we’ve missed all the warnings, totally misread the corner and we find ourselves rushing into a massively tightening corner and going too fast to make it round by leaning over a bit more whilst maintaining our speed.

Well, the first obvious point to make is that even if we’re riding a bike with huge amounts of engine braking, shutting the throttle simply won’t get the job done if we’ve made such a mess of the approach. If we’re riding a two stroke shutting the throttle won’t even begin to slow us down!

And it should also be obvious that if we do shut the throttle weight transfers to the front of the machine. Thus the rear wheel which is actually doing the slowing down is NOT the best one for losing speed with – that’s why bikes with huge amounts of engine braking have slipper clutches, because the deceleration forces actually UNLOAD the rear tyre and make it prone to skid.

Which leads us to the brakes. Ken mentions getting the bike upright and braking in a straight line. It’s an option, but generally I’ve found that unless I’m already scraping the undercarriage, if I’ve room to do that I’m not going too fast to simply lean over more and make the turn anyway.

But on occasion we have to slow from speed to a near-stop. Unless we’ve made a total mess of reading the bend, it’s more likely to be forced on us by an obstacle in the middle of the bend rather than simply a bend that’s tightening up dramatically, but nevertheless, let’s continue the logical explanation.

There’s a far better technique than standing the bike up to brake, and that’s to brake in the curve. In point of fact we’ll lose far more speed far more quickly by applying the brakes than we’ll ever manage by closing the throttle!

But we’re told that braking in corners is a no-no. But racers do it on the track all the time. All that’s really needed is a bit of understanding of the issues and some finesse with the controls.

The most important is probably to realise that if we’re leaning over and we haven’t already fallen off, there’s grip available to brake. There may not be much if we’re carrying a lot of lean, but if we’re still on two wheels, there is by definition some spare traction for braking.

We also need to be really smooth and subtle with our application of the brakes and we need an equally smooth release. True, the bike tries to sit up as the brakes go on, but we can deal with that with a little firmer application of countersteering pressure.

Given that we SHOULD go into any bend able to stop in the distance we see ahead in the bend, at the first sign the bend is tightening significantly we’ll still be at only a moderate lean angle and we can use the distance we can see ahead to get on the brakes and start losing some speed before the bend tightens up.

As the speed drops, if the radius of the turn remains constant the lean angle of the machine will decrease and we can apply progressively more brake right down to a standstill. Even if the bend tightens significantly, and we have to maintain our lean angle whilst braking and slowing, we’ll still slow distinctly faster than by shutting the throttle.

Sometimes I really think it helps to look at the machine control aspects of any situation and not simply blindly accept advice that dates back to the 1960s, 50hp Triumph Saints and skinny teflon tyres.

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