Using the apex

[Dr Jekyll]

I was watching an 'advanced riding' demo on youtube (I'll post the link when/if I find it again) and the police rider on a twisty road referred several times to 'using the apex'.

This surprised me because I always thought the roadcraft attitude was 'apex? what's an apex?'.

How do you 'use an apex' on the road? These didn't seem to be wide open bends where a racing line might be acceptable.

[Martin A]

A good way of using the apex (in this description, the furthest that part of the kerb or centre line of the road appears to be toward the centre line of the car the when approaching a bend, and not the middle of the bend nor clipping point) is as a reference point rather than a target point. Aiming for the apex (unless the exit is visible) will usually result in less smooth, and therefore less stable cornering.

Aim to have a margin of error on the inside of the bend at the apex. As you approach this point you will gain more information as to what the road does further ahead.

Hope this helps

Best regards

Martin A

[davepoth]

The apex does give you a margin for error - usually it will mean less steering and braking, giving more traction.

[RobM77]

Any cornering line is going to have an entry, apex and exit, it doesn't have to be a racing line. On the public road one should aim for the safest line around a corner, which is determined by three things, in no particular order:

1) your visibility (out of your car)
2) visibility of your car to other road users (or potential road users - e.g. pedestrians).
3) maximising the speed around a particular corner where the limit of grip will be reached, so whatever speed you choose will be as far away from the limit speed as possible.

By the use of the word "use" in "use the apex", rather than "aim at the apex" it sounds like the instructor was quite rightly talking about what Martin mentions above. Entry, apex and exit are waypoints/references, not targets. If you stare at any of the three your driving will tend to become jerky and lose its flow, which applies on track and road. On the road one of the major differences is that if you're staring at your chosen apex, then you might miss hazards up ahead.

[Dr Jekyll]

So for example.

Suppose I am approaching a left hand bend, staying as far out to the right as seems prudent until I can see through it.

Once I get visibility I see that the exit is clear and the next hazard is a right hand bend, I decide that in the circumstances I want to approach the next bend from a left hand line. So I turn in from the crown of the road to just clear of the gutter and maintain this position until the next bend.

Is the apex in this situation the point where I get as close to the left as I'm going to get?

[RobM77]

Dr Jekyll said:

So for example.

Suppose I am approaching a left hand bend, staying as far out to the right as seems prudent until I can see through it.

Once I get visibility I see that the exit is clear and the next hazard is a right hand bend, I decide that in the circumstances I want to approach the next bend from a left hand line. So I turn in from the crown of the road to just clear of the gutter and maintain this position until the next bend.

Is the apex in this situation the point where I get as close to the left as I'm going to get?

It's the line you'd take on a race track for an extremely tight hairpin - a very late apex. You do it on a race track to give you grip for accelerating out of the corner, and you do it on the road to give you grip for the unknown part of the corner (you might suddenly spot gravel on the road, so it pays to plan to be cornering as little as possible in the bit you initially can't see), plus of course to maximise your visibility of the corner, and make yourself seen as much as possible for anyone that might be around that corner.

I agree though, the use of the word apex is a bit confusing. A focus on the three points I list in my first post is more prudent - it also keeps what you're doing in your mind, rather than just a line someone's drawn in a book.

[7db]

RobM77 said:

1) your visibility (out of your car)

Vision, usually, or sometimes view.

[RobM77]

7db said:

RobM77 said:

1) your visibility (out of your car)

Vision, usually, or sometimes view.

Sorry, yes, vocabulary block there on my part. See and be seen us what I think of :-)

[7db]

RobM77 said:

See and be seen us what I think of :-)

is

[Strangely Brown]

Dr Jekyll said:

Is the apex in this situation the point where I get as close to the left as I'm going to get?

Yes. The "apex" of any corner is not a fixed point on the ground. It is, perhaps, easiest to think of it as the point at which you have finished turning "in" and are now beginning to turn "out". i.e. applying the power and straightening your line. In relation to the physical corner, it can be early, late or anywhere you choose to make it depending on your particular circumstances.

[RobM77]

7db said:

RobM77 said:

See and be seen us what I think of :-)

is

iPhone knows best

Sorry - PH on the iPhone is infuriating, as it won't let you go back and edit your posts, even before you click submit, and it always changes my words into something else!

[7db]

Strangely Brown said:

Yes. The "apex" of any corner is not a fixed point on the ground. It is, perhaps, easiest to think of it as the point at which you have finished turning "in" and are now beginning to turn "out". i.e. applying the power and straightening your line.

I like this definition (the point of smallest radius of curvature), although it does tend to be supplanted by clipping point.

Strangely Brown said:

In relation to the physical corner, it can be early, late or anywhere you choose to make it depending on your particular circumstances.

Pro tip: make sure the apex is on the tarmac.

[Strangely Brown]

7db said:

Strangely Brown said:

Yes. The "apex" of any corner is not a fixed point on the ground. It is, perhaps, easiest to think of it as the point at which you have finished turning "in" and are now beginning to turn "out". i.e. applying the power and straightening your line.

I like this definition (the point of smallest radius of curvature), although it does tend to be supplanted by clipping point.

Technically, it's not the smallest radius of curvature. In fact, it's actually a larger radius than the curve would be had you followed a line directly along the centre of the lane (this is a good thing). It is, as the OP suggested, simply the closest point that you will get to the inside of the turn. I was just trying to provide a different way to visualise it. Hope I didn't muddy the waters.

7db said:

Strangely Brown said:

In relation to the physical corner, it can be early, late or anywhere you choose to make it depending on your particular circumstances.

Pro tip: make sure the apex is on the tarmac.

Ah, yes, good point. Perhaps that is where I have been going wrong.


Edit to fix quoting.

Edited by Strangely Brown on Monday 6th September 08:33

[7db]

Strangely Brown said:

Technically, it's not the smallest radius of curvature. In fact, it's actually a larger radius than the curve would be had you followed a line directly along the centre of the lane (this is a good thing).

I think we all agree that the line taken by you and the line taken by the tarmac-laying machine might be different (hence my earlier advice). Apexes usually refer to the line taken by you, and as you travel along that line you will have a radius of curvature at each point. The apex lies where this value is a minimum.

Strangely Brown said:

It is ... the point at which you have finished turning "in" and are now beginning to turn "out". i.e. applying the power and straightening your line.

Strangely Brown said:

It is ... the closest point that you will get to the inside of the turn.

The points you have described are not necessarily the same points. The first is the minimum radius of curvature - the "elbow" of the line. The second is the clipping point: where the vehicle is nearest the inside kerb. There are co-located occasionally, and are in the "classic" symmetrical racing line. However for most practical slower corners - particularly on the road where one is looking for increased sight-lines rather than use of grip - the apex will be considerably earlier than the clipping point, where one might already be mostly straightened and at wot.

[Strangely Brown]

7db said:

Strangely Brown said:

Technically, it's not the smallest radius of curvature. In fact, it's actually a larger radius than the curve would be had you followed a line directly along the centre of the lane (this is a good thing).

I think we all agree that the line taken by you and the line taken by the tarmac-laying machine might be different (hence my earlier advice). Apexes usually refer to the line taken by you, and as you travel along that line you will have a radius of curvature at each point. The apex lies where this value is a minimum.

OK, I see how you're describing it now. This is true for corners where the radius of *your* turn varies. It is not true for a turn of constant radius where the apex and clipping point coincide. In that case the apex/clipping point are usually on the largest practical radius. I know what I meant to sat, I guess I didn't express it well.

7db said:

Strangely Brown said:

It is ... the point at which you have finished turning "in" and are now beginning to turn "out". i.e. applying the power and straightening your line.

Strangely Brown said:

It is ... the closest point that you will get to the inside of the turn.

The points you have described are not necessarily the same points. The first is the minimum radius of curvature - the "elbow" of the line. The second is the clipping point: where the vehicle is nearest the inside kerb. There are co-located occasionally, and are in the "classic" symmetrical racing line. However for most practical slower corners - particularly on the road where one is looking for increased sight-lines rather than use of grip - the apex will be considerably earlier than the clipping point, where one might already be mostly straightened and at wot.

Yes, agreed. My description did confuse that point.

[7db]

I think the radius of most corners varies in the real world (unless you're a *really* big fan of roundabouts). It's necessary for turn-in and powering out of the corner, although a nicely balanced mid-section might have a relatively stable radius of curvatur. I would expect it to have a fairly well defined apex, particularly so on road driving.

The confusion with the term "apex" is that it is often used to refer to where your line meets the apex of the tarmac (ie the clipping point), and in particular where this is relative to the natural apex. Thus a late apex line has an point of minimum curvature earlier than an early apex line...


And just in case you have an iPhone:

Strangely Brown said:

I know what I meant to sat, I guess I didn't express it well.

say

[LordGrover]

7db said:

an point ...

And just in case you have an iPhone:

Strangely Brown said:

I know what I meant to sat, I guess I didn't express it well.

say

a point ...

iPhone for you too?

[Strangely Brown]

7db said:

And just in case you have an iPhone:

Strangely Brown said:

I know what I meant to sat, I guess I didn't express it well.

say

No, just disobedient fingers.