How to Handle Decreasing Radius Corners

Nothing gets a rider’s heart jumping into their mouth and their eyes opening out like saucers, then finding themselves in a decreasing radius corner going too fast. It can set off instincts like nothing else on a bike, with riders chopping the throttle and standing the bike up, causing more trouble than it fixes.

A decreasing radius corner is essentially a corner that tightens up. That means that if you take a normal mid apex line into the corner as you might on a constant radius turn, you’re going to find yourself running wide unless you have enough in ‘reserve’ to really lean the bike over. That’s not a good place to be if you have oncoming traffic (or other things to crash into).

So, how can you spot a decreasing radius corner? And what’s the best way to approach them? Well, read on (or watch on) to find out.

Spotting a Decreasing Radius Corner

It should go without saying that if you’re riding on unfamiliar roads, you should be going at 6/10ths of your limits to begin with.  That way, if you do find yourself in a tightening corner, you’ll have the ability to keep rolling on the throttle and lean the bike over to exit the corner smoothly.

That said, you can, with some practice learn to spot a decreasing radius corner on the road.

In a decreasing radius corner, you’ll find that the further you go into the corner, the vanishing point will appear to be coming towards you. This effect is quite subtle compared to how a vanishing point moves away in an increasing radius corner, but with enough practice, you’ll begin to spot a tightening turn, allowing you to position the bike correctly for a later apex.

Taking a Decreasing Radius Corner

A decreasing radius corner requires two things – late turn in and late apex. Have a look at the diagram below.

By turning in late, you cut down the lean angle required to make the turn. Same with the late apex. But putting theory into practice isn’t always easy, so let’s break it down.  We’ll cut the corner into three sections to help make it easier.

A Decreasing Radius Corner Image

The first part of the turn involves staying as wide as possible until you turn in. Some riders may find this difficult, as you’re well into the turn before you actually turn in and commit. The natural inclination is to look towards the inside of the corner straight away – but in this situation, it would mean you hit the apex around the midpoint, and as the corner tightens, it would throw you wide.

The best way to overcome this is simple – look where you want to go. As you enter the corner, spot your turn in point and look towards it.

Remember throttle control too. Again, a rider may be apprehensive about being wide so far into the corner and reduce throttle. That will lower speed and therefore the bike will move towards the inside of the corner. You’ll need neutral to slightly open throttle to maintain the wide line.

Upon hitting the turn in point, you’re in the second part of the corner. Flick the bike over quickly and head for your apex. Immediately roll on the throttle (don’t chop it whatever you do) and put in enough lean so you don’t run wide. Rolling on at this point will unload the front end and put as much grip as possible into the rear tire. Because of taking such a late turn in, you won’t need to lean in nearly as much and that allows you plenty of reserve should you need it.

Third, upon hitting the apex, continue to open the throttle and make a nice smooth exit. these steps will probably take some practice, as the approach to a decreasing radius corner can feel counter intuitive. If you have access at a local track that features such a corner, keep practicing by taking later and later turn-in points until you feel you’ve got it right. Alternatively, do the same on a quiet piece of road at lower speeds until you feel confident.


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  • BobtheDob

    One suggestion – you should probably treat every corner on the back roads as a decreasing radius one. That way, you can see further around all corners, which give you perhaps that extra bit of time to avoid something nasty.

    • Yeah, good point. It’s always best to be as safe as possible on the open road. Vision is a big component of staying safe.

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