Braking in corners

[LittleGreyCat]

One thing not mentioned specifically (as far as I could see) is the "line" taken through corners.

If you just follow the corner you may have to keep tightening up the turn, and if you drift a bit then you have to tighten even further to avoid taking to the hills. This isn't always the most stable way to corner.

If you watch F1, for example, there is a "racing line" through the corners. At least, some corners.
Roughly, come to the corner straight, brake hard, turn to cut across the apex of the corner in a straight line, turn again as you come out of the corner. In effect making it two sharp corners with a straight bit across the apex.

If you have a clear road and sufficient view you can do something similar on a bike.
Approach the corner wide, braking hard.
Ease off the brakes and turn sharply aiming at the apex.
Brake hard again (if required) in a straight line.
Ease off the brakes and turn sharply aiming down the road.
When I manage this correctly it seems to make the corners easier.

[nigel8322]

Looking at the physics... the maximum force on the tyre by the road will be the coefficient of friction (maybe 0.6 or a bit more with a good tyre on a grippy road) times the weight on that tyre. It doesn't much matter whether the force is related to braking or cornering- if you try to do something that needs a bigger force than the above (eg by cornering too fast or braking too hard or a combination) the tyre will skid and, more than likely, especially if it's a front tyre, you will fall off (we've all been there....).
Braking in a straight line (using all the grip to brake) followed by cornering (using all the grip to corner) may exercise the brain cells less, but it isn't the quickest way round (which doesn't matter to me, but does if you're racing). Skillfully entering the corner and reducing the braking effort as the cornering forces increase is quicker (watch the Formula 1 drivers) because you are using all the grip available all the time.
However, on a steep incline like on a hairpin bend, if you don't brake in the corner, you will be accelerating because of gravity (the cornering force is at right angles to the direction of motion and won't slow you at all) hence it is all too easy to accelerate until the force available isn't enough to take you round the corner...and you fall off anyway or take a wider arc and go off the road. So you probably do need to brake through most of the corner on this type of road. So sensitivity and 'feel' are needed unless you go very slowly the whole way round. Well done if you've got this far. As one of my students said 'a physics teacher is one who speaks while others sleep'.

[mattheus]

Looking at the physics... the maximum force on the tyre by the road will be the coefficient of friction (maybe 0.6 or a bit more with a good tyre on a grippy road) times the weight on that tyre. It doesn't much matter whether the force is related to braking or cornering- if you try to do something that needs a bigger force than the above (eg by cornering too fast or braking too hard or a combination) the tyre will skid and, more than likely, especially if it's a front tyre, you will fall off (we've all been there....).
Braking in a straight line (using all the grip to brake) followed by cornering (using all the grip to corner) may exercise the brain cells less, but it isn't the quickest way round (which doesn't matter to me, but does if you're racing). Skillfully entering the corner and reducing the braking effort as the cornering forces increase is quicker (watch the Formula 1 drivers) because you are using all the grip available all the time.
However, on a steep incline like on a hairpin bend, if you don't brake in the corner, you will be accelerating because of gravity (the cornering force is at right angles to the direction of motion and won't slow you at all) hence it is all too easy to accelerate until the force available isn't enough to take you round the corner...and you fall off anyway or take a wider arc and go off the road. So you probably do need to brake through most of the corner on this type of road. So sensitivity and 'feel' are needed unless you go very slowly the whole way round. Well done if you've got this far. As one of my students said 'a physics teacher is one who speaks while others sleep'.

I'm going to award 9/10 here. A bit harsh, but he didn't mention Friction Circles. Or include any diagrams.


Incidentally, that moment on a nice descent where gravity gives you a real shove as soon as you let off the brakes at juuuuust the right moment in the corner, has to be in my Top 5 sensations on a bicycle. Happens several times on the drop into Tregaron. Tidy.

(unless you misjudged the corner - but that's a key part of the learning experience )

[Mick F]

Many hairpins hereabouts, not least the couple on the A390 not three miles from here.
https://www.google.co.uk/maps/@50.53502 ... 312!8i6656
Downhill hairpins you MUST brake as you'd never get round them. Same in the car. You MUST brake.

With racing, the traffic isn't coming the other way so you can use the whole road.
As we live in the real world with real traffic, you have to stay on your side of the road.

I have driven in some hilly places but not in Cornwall
I read some advice: use the same gear to drive up as to drive down, seems to make sense maybe, one should not use the brakes much

Coming up that hill I linked on the A390, you'd be fine in 4th gear.
It's not steep at all, but going down on a bike .......... like I often am ................. by not braking, you WILL NOT get round the corner.
Ditto in a car.

In a car, you could go into 2nd or 1st before you get to the bends, but it's very much overkill.
Just stay in top gear and dab the brakes on the corners.
Ditto on the bike.

Just brake. You MUST brake, as you'd be off on the other side of the road if you didn't.

Say you stopped just before the bend.
Off you go, but you'd still be braking to get round.

[Audax67]

I remember having an unpleasant moment descending the Grand Ballon in the Vosges, when I set myself up for a regular hairpin only to find that on the bend itself the smooth tarmac gave way to setts (blocks of paving stone) which required a much slower speed than I was taking into the corner.

Yes, it's famous for that. I suppose it's more durable than tarmac but it makes some folk downright irate. I knew about it in advance but I still got p'd off.

[roubaixtuesday]

One thing not mentioned specifically (as far as I could see) is the "line" taken through corners.

If you just follow the corner you may have to keep tightening up the turn, and if you drift a bit then you have to tighten even further to avoid taking to the hills. This isn't always the most stable way to corner.

If you watch F1, for example, there is a "racing line" through the corners. At least, some corners.
Roughly, come to the corner straight, brake hard, turn to cut across the apex of the corner in a straight line, turn again as you come out of the corner. In effect making it two sharp corners with a straight bit across the apex.

If you have a clear road and sufficient view you can do something similar on a bike.
Approach the corner wide, braking hard.
Ease off the brakes and turn sharply aiming at the apex.
Brake hard again (if required) in a straight line.
Ease off the brakes and turn sharply aiming down the road.
When I manage this correctly it seems to make the corners easier.

This.

Nervous descenders tend to hug the kerb, a lethal strategy. You should always enter corners as wide as the road allows. As well as requiring a much less sharp turn, reducing the risk of crossing into any oncoming traffic, it also gives much better visibility of the road ahead, and makes it far less likely to encounter gravel or unexpected potholes.

IMO this includes going on the "wrong" side of the road into left handers (in the UK), or if not safe to do that, at least taking the centre. It applies whether attempting a fast, or a leisurely descent.

I once did an alpine descent in a mass participation event and was quite stunned by how poor the descending was. Most people seemed to be kerb huggers and every hairpin near the top featured bloodied cyclists. It's a mystery to me how you can get to be fit enough to cycle up mountains yet unable to descend in a safe manner.

[Brucey]

if you want to see the best racing lines for bicycles then you should look at a motorcycle race where the bikes are not very powerful. Currently Moto3 is quite like this.

They try to carry as much speed as possible through the corners and in essence this means describing the biggest possible radius through the turn, consistent with staying on the tarmac. The more acceleration and braking you have available, the more the line tends to approximate to a parabola than a constant radius.

You can't often use full racing lines on public roads, but on some descents with hairpins, you can get a good enough view of the road ahead that you can use all the road if you like.

The racing lines described by F1 cars and MotoGP bikes are very misleading; these machines have super brakes and are very powerful; furthermore they only accelerate and brake properly when they are 'going in a straight line' and 'more upright than you might imagine' respectively. So these powerful machines tend to take thruppenny bit lines through some corners. This is often referred to as 'squaring the corner off' or similar. Often they talk of 'getting the car/bike turned' before using much throttle; in an F1 car even a small amount of steering lock can have a profound effect on the acceleration.

If you try and copy these F1/MotoGP lines on a bicycle, it is a very long way from the fastest way through most corners, and in the company of others, you are liable to cause an accident.

cheers

[Marcus Aurelius]

Try to get your braking done in a straight line. Break the corner down into segments. 1. braking zone. Try to brake in a straight line as much as possible.2 Turn in point. Pick a point at the edge of the road which enables you to lean in and reach the apex of the corner with minimal turning of the wheel. 3. The apex ( geometrical middle of the curve ) is the point of the road you’re aiming at, trying to maintain as straight a line as possible, the clipping point is the point where you actually touch the apex, and the point at which you need to be getting the power back on, then 4. aim for a point on the opposite side of the road which you can get to without steering too much. Use all of the road. You can ‘trail brake’ where you don’t brake until the turn in point, and keep the brakes on until you reach the clipping point / apex, then release and get the power on, but that’s a bit tricky to get right, although it means you can brake later, and harder, so carry more momentum into the apex. Then keep the power on until you reach the steady position you normally ride in. Think slow in fast out, get the power on whilst exiting the corner / as soon after the clipping point as possible.
Here it is explained graphically.

[NATURAL ANKLING]

Hi,

I have driven in some hilly places but not in Cornwall
I read some advice: use the same gear to drive up as to drive down, seems to make sense maybe, one should not use the brakes much

In a car, you could go into 2nd or 1st before you get to the bends, but it's very much overkill.
Just stay in top gear and dab the brakes on the corners.
Ditto on the bike.

Not my advise Mick, unless I misunderstood you?
I do not use the brakes much on the camper, the braking from a normally aspirated diesel engine with a long stroke crank is colossal!
I commonly use 2nd gear (although its 30 max speed 2nd, 45 in 3rd) on steep downhills in devon and cornwall.
I thought thats what good safe drivers do?
Failure to use gearbox correctly will lead to brake failure and loss of control leading to skids etc.

My mate drived his diesel by not changing down on hills.........result was driving into a stationary vehicle waiting patiently for him at bottom of hill

Like I said maybe I misunderstood what you were saying?

[thatsnotmyname]

Use all of the road.

....and get hit by a truck coming the other way. Great idea.

[Cyril Haearn]

Right again Mr Ankling, I seem to remember something in the driving test about using the gears correctly

[roubaixtuesday]

Use all of the road.

....and get hit by a truck coming the other way. Great idea.

Using all of the road makes it less likely you'll get hit by a truck. It is, genuinely, a great idea.

[foxyrider]

There are a surprising number of hairpin (or close to) bends in the UK, somewtimes in the most unlikely places, so there is opportunity to hone your skills before hitting the big mountains abroad. Do make sure you are happy with how the brakes are set up, i like mine set with minimal lever movement before biting, its less tiring on multiple braking descents. Fast, wet descending can kill brake pads very quickly if not done properly so make sure you have some adjustment left - you may need it

I've done Alpine passes with 20 plus turns, fatigue can then be a factor in your safe descent! i would echo a lot of the advice given and of course, practice is the key to improving!

So first thing with any corner, look at where you want to be, at least 20m ahead of you. The time to look at the view is on the approach or after exiting, not through the turn!
As we are talking descents, push your weight backwards to load the rear of the bike
Speed reduction braking should be smooth and completed before you start the turn
Control braking through the turn, again smooth and likely just skimming
Inside leg up, you get extra ground clearance and better balance
Wide in, then clip the available apex point (this may be the whiteline if its an outside turn) then allow the bike to drift to the exit point
Accelerate or at least un brake only as you exit the turn

With a bit of practice you can descend a series of 'pins as fast as any 'sane' car driver, they might be faster on the straights but you can get through most turns quicker. The turning point for me was a descent of the 28(?) turn Silvretta pass on a fully loaded bike in very wet conditions, a lot of the turns are under 200m apart with steep ramps - the only thing that passed me was a motorbike that i then caught on each succesive bend! Since then i've had the confidence to get around and down much quicker, once or twice i've misjudged a little and found myself on the tarmac edge but i've done that on just twisty roads too!

Other points worth mentioning, the stability of a slacker angled, longer wheelbase touring iron will make fast descending quite sketchy, the bike will drift to the outside of almost any bend however hard you try not to. Weight high up on the bike can result in somestrange handling characteristics on tight turns, a low centre of gravity will give better stability and control.

[Marcus Aurelius]

Use all of the road.

....and get hit by a truck coming the other way. Great idea.

Using all of the road makes it less likely you'll get hit by a truck. It is, genuinely, a great idea.

Quite right, experience has taught me this. If you remove the possibility of a hit ( by using all the road ) you reduce the probability of a hit.

[NATURAL ANKLING]

Hi,

Use all of the road.

....and get hit by a truck coming the other way. Great idea.

I see ban coming soon
But I digress....back on subject.
I commonly use as much of the road I need as long as you are not inconveniencing other users, and are safe about it to all road users.
So I don't ride / drive on the wrong side of blind corner forcing others to brake or ditch in hedge to avoid me!
That means I am happy to overtake cleanly, but restrict using all the road if someone might see me, like the fuzz