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I was reading "Riding in the Zone" by Ken Condon last night, and he had an interesting way of talking about braking and turning. It's a good book - glad I added it to the collection.

Anyway, everything from MSF up tells you to brake before you turn, and this is the "gospel", so to speak. However, many people still don't really understand the destabilizing force that braking adds to the equation.

I think Condon does it perfectly with the concept of the "Traction Circle", namely:



  • The black circle represents the limits of traction
  • The red arrow is braking force
  • The green arrow is lean angle
  • The blue rectangle represents the force of the braking and lean vectors.
Note that as the red line lengthens (more braking force), the green line must shorten (less lean angle) for the blue rectangle to stay inside the circle. Note also that the blue does not touch the circle - you always want to operate at less than the limits of traction.

None of this is to say you cannot brake in a turn - but it shows that the more you brake, the less you can lean. The maximum lean angle can only be had with no brakes, and maximum braking with no lean. Obviously, better tires and suspension will make the circle bigger - but the same proportional restrictions apply.

So what does this really mean? Bottom line is that taking a corner starts well before you start to lean - you should be judging the corner and setting your speed up with the bulk of your braking before the turn. That way, you can coast through the turn or, even better, add throttle to lighten the front / load the rear so the bike will track better.

Condon's book goes over this concept in more (and better) detail, as well as providing a wealth of tips about staying safe on the street. It also includes a DVD that reinforces the concepts in the book.

Good Read!

Luke
 

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Since I see a circle, and not a half-one, the same idea can apply while applying forces moving forward?
It seems that the more you accelerate going out from a bend, the more lean angle decrease naturally...
 

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thats similar to how the book sport riding techniques explains it. he says you have 100 points of traction and for example if you're using 70 for lean, you only have 30 left for braking or accelerating i believe. that's definitely a good book too
 

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Discussion Starter #4 (Edited)
thats similar to how the book sport riding techniques explains it. he says you have 100 points of traction and for example if you're using 70 for lean, you only have 30 left for braking or accelerating i believe. that's definitely a good book too
Nick Ienatsch, right? I bought that one at the same time as the Condon book - it's next on my list. Good to hear someone like it, makes me look forward to it even more!

TheMente, I would think so, and DoubleRR referred to that specifically. Anything that loads the tire is going to decrease the traction available for leaning. Also, adding power tends to make the bike stand up anyway.
 

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I am sure there's an equation about this in phisics, I am interested in how things work, but I am not fond with phisics laws...

It's just something I have experienced on two wheels: while braking the inertial mass of the bike (and biker's) makes the whole thing to reduce lean angle. If I brake more progressively I can keep leaning, but the sensation of being pulled upwards is still there. Is it related on how rigid the frame is?
 

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I'm too busy concentrating on the SUV driver using a mobile phone, and the sports car not indicating but looks like it might turn right, and potholes, and bits of loose gravel and, and lumps of concrete left by over filled concrete trucks, and patches of oil, and that buffalo that is thinking of crossing the road, and that pack of dogs that is giving chase, and.... and.... to consider circles and coloured arrows, and paragraphs of explanation and the gospel and destabalising force and limits of traction and vectors and angles of the dangle and condom and bottom line.

Stick with administrating, moderating and writing software, Luke; as an instructor you don’t make the cut. In my opinion.

Like too many teachers I have come across, you seem to know a bit, but it gets lost in the communication.

I think what you are trying to say is this:

1 - brake before a corner
2 - back off the brakes through the corner
3 - use a bit of throttle to balance the bike

If you brake too hard while leaning into a corner, you’ll land up on your arse.
 

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They explained it similarly in MSF course. My background on bicycles (and some nasty spills) prepared me for this pretty well. Judging turns comes pretty easily to me now. :)
 

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Right.
since that reduces down to simply tracing a radius along a circle, then

braking force = SQRT(r**2 - (leaning force)**2)

I think that's a little too simplistic, but the idea that one limits the other is sound :)
 

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Stick with administrating, moderating and writing software, Luke; as an instructor you don’t make the cut. In my opinion.

Like too many teachers I have come across, you seem to know a bit, but it gets lost in the communication.

I think what you are trying to say is this:

1 - brake before a corner
2 - back off the brakes through the corner
3 - use a bit of throttle to balance the bike

If you brake too hard while leaning into a corner, you’ll land up on your arse.
This is good if you are trying explaining to a sheep :O (so for about 35% of motoristic people).
Going a little further, honestly I think that a vector is a simple enough way to graphically represent forces playing in that circumstances.

The circle just indicates (with arrows!) that the bike must keep the balance, clearly showing the limits. You are not going to doing maths on this, but a iconic nice looking picture will make you keep that in mind better than some text.

2cents
 

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Kind of standard rules for cars too. I can't even count the number of times drivers hit their brakes mid curve.
Ive seen quite a few spin outs in the winter when cars in front of me use their brakes while they're inside a bend.
 

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when I drive in the mountains in 180* curves I sometimes use a little rear brake at the very beginning of the curve, where there is not yet a lot of traction. I don't know the logic behind that, but I think it helps me to lean faster. what do you think about that?
 

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Kind of standard rules for cars too. I can't even count the number of times drivers hit their brakes mid curve.
Ive seen quite a few spin outs in the winter when cars in front of me use their brakes while they're inside a bend.
True.

However in an ABS equipped car the driver would have a reasonable chance of maintaining control (would be less likely to spin out), especially if the car also has traction control. Technology can make up for driver error or lack of skill on four wheels.

On a motorcycle, ABS or not, if you brake too hard mid curve you'll be off your bike. Technology is no substitute for technique on two wheels.

If you don't believe me, go out and try it.

Sorry, no vectors and circles and coloured lines and arrows along with a few choice quotes from some illustrious academic or another. I learned my motorcycling at the School of Hard Knocks, and was tutored by Common Sense.
 

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when I drive in the mountains in 180* curves I sometimes use a little rear brake at the very beginning of the curve, where there is not yet a lot of traction. I don't know the logic behind that, but I think it helps me to lean faster. what do you think about that?
It's called "trail braking" and is something I do all the time. It settles the rear end, makes it squat a little, and helps with rear end traction. Get off the rear brake at the apex of the curve and get on the throttle. It's a lot of fun!
 

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Discussion Starter #16
Why Michael, I apologize for offending you. I'll count you as one vote for me wasting my time. When I start getting negatives from folks that wear protective gear, you may get your wish.

As a firefighter instructor, I often run into individuals who claim to have "twenty years of experience" when in reality they have "four years of experience five times". Even though I'm 54, I'm still interesting in learning new things, both from books and from others.

Luke
 

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Protective gear? Unless youre in a state with helmet laws I bet the majority dont wear gear.
Sadly, you're probably right. I certainly do but I wish I didn't have to when the weather is this hot.
 
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