How to Handle Decreasing Radius Corners

[EBF]

Hi guys,

Thought it might be a nice idea to kick start some posts on riding skills.

I recently wrote an article on my blog about decreasing radius corners, which I've posted below. I've also made a video which I filmed in Thailand. Enjoy.

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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.

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.

Following 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.

[RubberSideDown]

The text is pretty much a re-wording of TOTW II (which I see you have on your reading list), but I quite liked the video- seeing it on the street as well as the track is a good way to illustrate the point.

[cooked]

? isn't this one of the first things you learn?

[VocalNeal]

On the open road the key would be slow in fast out, and then spotting the damn thing in the first place.

[EBF]

? isn't this one of the first things you learn?

Certainly isn't taught in any lessons to get a license in Australia where I first rode.

Maybe they teach it at Thai lessons?

[RubberSideDown]

? isn't this one of the first things you learn?

Certainly isn't taught in any lessons to get a license in Australia where I first rode.

Maybe they teach it at Thai lessons?

I thought that was a strange comment as well- properly executing a DR turn isn't a newbie skill.

So much of riding well is counterintuitive (i.e. training yourself to properly crack the throttle to maintain your line when hitting the brake seems like the right thing to do)- when I first read TOTW II, so many things became clear, and it illustrated how little you need in the way of skills to merely qualify for a license.

[EBF]

? isn't this one of the first things you learn?

Certainly isn't taught in any lessons to get a license in Australia where I first rode.

Maybe they teach it at Thai lessons?

I thought that was a strange comment as well- properly executing a DR turn isn't a newbie skill.

So much of riding well is counterintuitive (i.e. training yourself to properly crack the throttle to maintain your line when hitting the brake seems like the right thing to do)- when I first read TOTW II, so many things became clear, and it illustrated how little you need in the way of skills to merely qualify for a license.

So true. So much of it is physics. Who thinks about physics when driving a car? Yet it is essential with a bike.

[cooked]

I learnt it after falling off once and thinking about it. I did major in Physics, true, but it isn't rocket science.

[gmac]

All well and good but don't forget to factor in the sand and loose dirt found across many smaller roads in rainy season. The back roads outside Pattaya are especially bad at the moment with a lot of new building work going on.

[brfsa2]

I liked the video.

thanks for posting!

[pistachios]

For non native speakers, what exactly do "rolling the throttle" and "cracking the throttle" mean?

[nikster]

Huh? If you're racing on a race track this is undoubtedly a good skill to have.

But if you're on the road, only go as fast as you can see. It doesn't matter if you're riding on "unfamiliar roads" or familiar ones. They're roads, where the unexpected can happen. I think I read somewhere that the majority of accidents happen on the way home.

And that is actually the primary thing one learns doing a driving license where I come from. We have this extensive 40 hour mandatory course and I swear 20 of those hours were repeated drills of "ONLY GO AS FAST AS YOU CAN SEE".

If you do that, you will see the decreasing radius corner. You'll also see that truck parked behind the corner, and the cow on the road, and the fallen tree, and the oncoming truck.... you get the point. It's just common sense. It means go only so fast that you can still come to a full stop in your current field of vision.

[brfsa2]

For non native speakers, what exactly do "rolling the throttle" and "cracking the throttle" mean?

rolling the throttle => increase throttle -> accelerate

"Rolling on at this point will unload the front end and put as much grip as possible into the rear tire"

when accelerating, front end will try to lift, loosing contact with the road, the weight will be transferred to the rear wheel.

that's why you smootly accelerate when leaving the curve, so that the rear tires will be more like glued to the road. but too much throttle is not good either.

best movie ever is TOTW 2.

[RubberSideDown]

^^

Knowing how to properly execute a certain type of turn is a good skill anywhere, be it road or track.

Obviously on a racetrack speed is a factor, but on the street the important thing is being able to hold a proper line without running wide or cutting the turn too sharply (unless it's necessary to do that to avoid an obstacle)- whatever helps you to have better control of your bike increases your margin of safety, regardless of your speed.

Too many riders are completely clueless in a DR turn (or any turn, frankly), and the tips EBF is trying to pass along are actually very helpful in any situation- notice the title of this thread isn't 'How to take a DR turn as fast as possible' but, rather, how to 'handle' one.

[monty1412]

good video, I think we have come unstuck on a corner that tightens on itself one time or another

[Johnsy]

Great post man, valuable info for any road user, this cornering skill is something everyone can improve. The only point I would expand on is; Go into the corner cold and come out hot. Too many people go in fast (hot) and have to brake and decelerate which gets the bike all out of shape, no bike likes that, all bikes like being driven through a corner and they're way more fun and stable if you are driving them through a corner.

[cooked]

Basically, the sharper the corner gets, the slower you drive. At the same time you try to increase the radius of the curve as far as is safe. I know that passengers I have taken over the years find this very strange, think I am dangerous. I used to drive behind a BMW regularly after work, going up into the mountains, in my little Citroen. (I knew the driver). I couldn't overtake her on the straights, of course, and on the curves I had to brake.

[RubberSideDown]

^

You can't equate cars and bikes as far as turns go.

Do you ride a motorcycle?

[mania]

Always good to have an idea before it is needed about how
to handle situations that may occur. Of course on a track is one thing

& easily practiced using the whole width of track but on the road it is
especially good to know your options for various scenarios.

Folks can easily find themselves panicked in a decreasing radius turns
& end up over the center line or worse depending on degree of panic as they
run wide.

I can only speak for myself but I follow usual braking before the turn, settle the chassis
get off the brakes & roll on throttle as exit appears type riding.

But I have been surprised in my life many times.

At those times I use slight rear brake for
speed adjustment while keeping leaned over & lean/tighten more as required.

I am not saying it is for everyone & many I am sure will disagree.
But for myself/ the way I ride it is how I do it preferring not to upset front/rear
weighting/balance.

edit : But to be clear 99% of the time I am in a turn at proper speed for that turn

& this rear brake trailing is a small adjustment. Of course it is not

meant to save someone who is in way too hot to begin with

[maximillian]

Thanks OP. It's good to come up with this. And the video is great too, EXCEPT for the loud background music that makes it difficult to understand what's being said.

Thinking of my motorbike lessons 47 years ago, I must say it was a joke. 2 hours on a scooter behind the car of the instructor. No communication while riding.

Yes, me too have come in situations when all of a sudden there wasn't enough street left. Lucky me, I never fell or rode into oncoming traffic.

Nowadays I ride very defensively, especially when I ride with a pillion.

Only the day before yesterday an aquaintance got instantly killed in a bike accident. Don't know the details yet.

Thanks again for your good advice.

[ATF]

For those that may be confused because the pic is really for a track. You won't see many hairpin bends on a public road unless you are ascending a mountain.

But this is the real danger, slowing down!

[soidogbob]

Good post and great vid.

While there is a lot of experienced riders about I see big bikes getting more popular and an increasing amount of posts involving accidents.

If even one person learns from this and saves some pain then result.

Can you do one on how to avoid crazy dogs that wander out in front of you?

[nikster]

It is a really good instructional video. It makes perfect sense - seeing the video none of this seems counter-intuitive at all.

I know what you mean when you say most people have no idea how to ride turns in general - they've never taken a riding course. I have a motorcycle driving license and spent quite a bit of time - well for a driving license - practicing. But they never taught me essential basics that you need in order to ride a motorcycle properly. My first bike was a D-Tracker and in hindsight I can say I had absolutely no clue as to how to ride it - pure luck that I got anywhere! I wrestled it around turns and I knew it felt wrong, and slow, but I didn't know how to do it better.

So I recommend everyone take a riding course. Honda, Kawasaki, Yamaha, and Ducati all offer them in Thailand. I've only been on the Ducati one but it was fun, very informative, and just as professionally done as you could imagine. We had more than 10 instructors, we had multiple stations with different skills to practice and one instructor on each end - the first tells you what you should do, then you do it, and then the one at the end tells you what you did wrong and what you need to do better the next turn. All participants left his course with skills way better than before.

I've learnt the following:

- Look where you want to go. If you ever ride figure eights, this is immediately obvious. If you look where you need to go, figure eights are easy. If you don't, they are impossible. This was the first lesson in the DRE riding course.

- Counter steering. Get the bike leaned over with minimal effort. Makes turns very easy.

- Throttle control - this is pretty counter-intuitive at first but staying on the throttle in turns makes for much smoother turns. 10% throttle or so is enough, just a little bit. Conversely you will mess up any turn if you brake once you are already in the turn.

Putting these together you'd ride decreasing radius turns exactly like in the video. Good to have that additional info but I would recommend to start with the basics that go into that solution.

PS: The only thing I object in the original post is this sentence: "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's false. If you are on the road, familiar or unfamiliar, never go faster than you can see. Most of the time that is a lot slower than the geometry of the turn would allow were it on a race track...

[dotpoom]

Now I get it..........I thought you were talking about horse riding.

[joshstiles]

soooooo....now you have moved your blog to TV

[BKKBike09]

"Never go faster than you can see". The best advice, and particularly so in Thailand.

Here's another instructional video on just that topic. Not entirely sure I'd have put this on YouTube if it was me, but he did, and here it is

[duanebigsby]

"Never go faster than you can see". The best advice, and particularly so in Thailand.

Love this advice!

I realized early on in Thailand that, as a photographer, I was going to try to look around a lot while riding.

Realizing that wasn't such a great idea I slowed down considerably while out looking for photo ops.

[ATF]

"Never go faster than you can see". The best advice, and particularly so in Thailand.

Here's another instructional video on just that topic. Not entirely sure I'd have put this on YouTube if it was me, but he did, and here it is

This has nothing to do with going fast or seeing in front. He obviously has never learned how to countersteer. Push right to turn right. Push left to turn left. He pulled right to turn right and went left which is what is supposed to happen.

His ABS probably saved him. If you have never ridden on a track you don't know how to properly ride a bike. Period.

[Johnsy]

"Never go faster than you can see". The best advice, and particularly so in Thailand.

Here's another instructional video on just that topic. Not entirely sure I'd have put this on YouTube if it was me, but he did, and here it is

Neither of them can ride, they both turn into the corner way to early which is what the OP was trying to point out. "ATF" says what needs to be said too; "This has nothing to do with going fast or seeing in front. He obviously has never learned how to counter steer. Push right to turn right. Push left to turn left. He pulled right to turn right and went left which is what is supposed to happen. His ABS probably saved him. If you have never ridden on a track you don't know how to properly ride a bike. Period."

[Dakling]

Good topic, some good info here. My 2 cents are that in non-track conditions you should always have enough lean angle in reserve to handle a DR curve without too much drama. The worst ones that I have ever had to deal with are the ones where you have a long sweeping high speed curve that near the end turns into a low speed tight DR curve. In those cases you need to scrub off speed before you get out of the high speed sweeper or you wont make the DR tight curve. The idea of simply staying on the throttle and correcting your line wont work if you are coming in too hot.

The other curves that are difficult to judge and execute properly are the curves that have a rise or depression in them, or if they are improperly banked. Likely the corkscrew at Laguna Seca is the most (in)famous example of this but when riding in the mountains it is common to have curves that do any or all of the following, decrease in radius, change grade, and/or change banking. It is near impossible to read a complicated curve correctly the first time over it and that's why riding at well below your limit is key on real roads. Never get too eager on the open road if you are not familiar with the stretch you are on and even then don't get too crazy. I think you are playing Russian roulette if you enter any curve aggressively in Thailand where you can't fully see the exit BEFORE you enter the curve.

Track days will increase your skill level (especially if it is part of a training program), but at the end of the day on the road your judgement and attitude count for more than pure skill. There are no concrete power poles on the edge of the track as there are on most roads in Thailand. not only that even if you do make it through the curve but you drift wide and run some other people off the road you are being irresponsible. If you can't make the curve without drifting out of your lane you are going too fast for the curve and/or your abilities.