Advanced Motorcycle Riding Course: Cornering - accurate lines

There’s always more than one line through a corner, but (usually) only one is correct. A steady throttle and a settled bike make staying on the right line easier and it makes adjusting a line quicker too

Posted: 23 August 2010
by Andy Morrison

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So far we’ve looked at the important decisions approaching corners; how we interact with the bike, general movement and weight shifting, as well as some of the elements affecting position, speed, braking and gear choices. This month we’ll look at what we can do in the corner and the most common problems encountered.

Slow in – Fast out

Let’s assume we’re just about to tip the bike into a fairly tight (sub-40mph) blind right-hander. We’ve followed all the advice given previously – being totally relaxed and in an ideal position. Now factor in a common rider error:  ENTERING THE CORNER ‘SLIGHTY FAST’.

The bike is tipped into the corner and because of its entry speed the line is fixed tight to the left while the angle of bank is quite acute. Some riders think this is the correct line if they need to stop quickly. However, with most of the tyre grip used up by speed and cornering forces, the amount of braking force available is almost nil. Apart from this, a lot of corner entry speed is rarely the quickest way through the corner. If we go in with a reserve of speed it can be used in our favour to open the line up, resulting in quicker exit speed. (Assuming there’s nothing to affect the line like opposing traffic in these examples).

Speed V Radius

The difference a change in speed makes to a bike’s radius is substantial, and much more than most riders appreciate. In the same way braking distances are governed by physics, (double the speed, quadruple the braking distance), cornering is governed similarly. If you lean a bike to a specific angle and maintain it while travelling at a certain spped, the bike will, assuming all other factors remain constant, go round the corner on a constant radius. Double the bike’s speed, keep the same angle of lean and you quadruple the radius.

In the next scenario the rider enters a fast sweeping corner and for whatever reason, at the point where the bike is tipped in, the rider feels uncomfortable with the speed. The result is they naturally enter the corner with a closed throttle. The chances of keeping a very accurate line until the view opens up is now almost impossible. The bike’s natural tendency now is to tighten its radius simply because it’s slowing down. The rider then tends to fight the bike’s natural course ending up in a series of line changes commonly called thrupenny-bitting (a 17th century coin like today’s 50p).

The trick is to be comfortable with entry speed so you can open the throttle and stabilise speed just before the bike’s tipped in. The bike then feels much more stable and minor variations in the natural radius of the corner can be dealt with easily. By subtle changes in speed, angle of lean, or a combination of both; smooth cornering can be achieved.

Linking corners together

Using throttle to adjust the bike’s radius is an advantage in a number of ways and really useful linking one corner to the next. It’s easy to get carried away in a series of corners and be tempted to drive the bike through and out of each successive corner. If we’re not careful we can easily push the bike into places we don’t really want to go. Statistically, mistakes taking left-handers are one of the major causes of crashes – so what you do with the throttle is really important. Whenever you are presented with a series of corners the most efficient way through them is generally to exit one corner in the correct position for the next. This is particularly important if there’s not much of a straight between the two corners.

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I've spent loads of thrupney bits in my time and I'm pretty sure I didn't grow up in the 17h Century.....

My missus also has a nice pair of threepeny bits, but that's another story


Posted: 22/01/2011 at 20:31

She has ;-)

Posted: 11/07/2013 at 10:14

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