Braking, Front? Rear? Both? Neither? Options

[Chip]

could you please put that into english. sounds like physics all over again (i like physics). from what gather at the second high point of a double turn? still makes no sense
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Nepster,

Now that you have a bike you'll start paying a lot more attention to how corners (AKA turns) are constructed. It's both physics and three dimensional (or Euclidean) Geometry.

Turns can be off camber. That means as you go through the turn, the turn slopes away from the inside which means if you enter the turn with a constant lean angle, you would actually drift to the outside because you're sliding down that slope (so to speak).

On camber means the turn slopes toward the inside and this is how most turns are on the street. They slope this way (e.g. like a NASCAR oval) to help keep vehicles on the road. The centrifigal forces that would push you off the outside of the road on an off-camber turn, actually help hold you to the road on an on-camber turn.

If you hear someone talk about an off-camber turn, pay attention.

The other two interesting aspects of turns are radius and apex. Like all circles, curves are also defined by their radius. A big sweeping turn has a large radius while a tight hair pin has a small radius. However, what is more interesting is when you enter a turn that has a decreasing radius. Again, watch out for these.

My first street accident was in a decreasing radius turn. Up to that point, I had been riding nice, constant radius (ergo predictable) turns. I could enter the turn and maintain a constant lean through the turn. No problem. However, when I went through this particular turn, the turn actually tightened up on me just beyond my field of view. I was carrying too much speed (for my skills at the time), I panicked, target fixed on the fast approaching outside of the turn and promptly went over the bank. Ouch. Decreasing radius turns surprise people all the time.

OK, that just leaves double apex turns. The apex of a trajectory is where the slope changes by passing from a positive slope to a negative slope. When the slope is zero, that is the apex. With riding the apex is actually a little more subjective. The easiest way for me to think about it is like this.

You can divide up the turn into two parts -- the first part and the second part. The first part is that section where the distance between you and the inside of the turn is decreasing. The turn is getting tighter. Once you pass the apex, the turn actually starts to open up again and the inside of the road starts moving away from you. After you pass the apex, you can begin to see further down the road than you could before -- that's what riders mean when they say "the road opened up."

Watch racers on the track and if you measure that distance to the inside of the turn, you'll be able to mark the apex points of each turn.

So, what is a double apex? Turn 7 at I/SP is a great example. If you look at the turn, it's actually in the shape of a square U. Rather than being a nice, constant radius turn, the turn apexes early then starts to open up for a few feet before you have to tighten up your line again to hit a second apex before hitting the next straight. It's like having two turns in one but you never really get to put your bike vertical in between. With double apex turns, you usually have to adjust your lean angle during the turn to make the second apex.

So what does this have to do with the rear brake? On lefthand, double apex turns, I can use my rear brake to initiate that change for the second apex. Again, this is something I learned in Freddie Spencer's Sport Rider II class. I'm not sure it has much application on the street but it's something to think about, I guess.

My brain hurts.

Cheers,
Chip

[sunseerie]

Nepster, 

Now that you have a bike you'll start paying a lot more attention to how corners (AKA turns) are constructed.  It's both physics and  three dimensional (or Euclidean) Geometry. 

Turns can be off camber.  That means as you go through the turn, the turn slopes away from the inside which means if you enter the turn with a constant lean angle, you would actually drift to the outside because you're sliding down that slope (so to speak).

On camber means the turn slopes toward the inside and this is how most turns are on the street.  They slope this way (e.g. like a NASCAR oval) to help keep vehicles on the road.  The centrifigal forces that would push you off the outside of the road on an off-camber turn, actually help hold you to the road on an on-camber turn.

If you hear someone talk about an off-camber turn, pay attention.

The other two interesting aspects of turns are radius and apex.  Like all circles, curves are also defined by their radius.  A big sweeping turn has a large radius while a tight hair pin has a small radius.  However, what is more interesting is when you enter a turn that has a decreasing radius.  Again, watch out for these. 

My first street accident was in a decreasing radius turn.  Up to that point, I had been riding nice, constant radius (ergo predictable) turns.  I could enter the turn and maintain a constant lean through the turn.  No problem.  However, when I went through this particular turn, the turn actually tightened up on me just beyond my field of view.  I was carrying too much speed (for my skills at the time), I panicked, target fixed on the fast approaching outside of the turn and promptly went over the bank.  Ouch.  Decreasing radius turns surprise people all the time.

OK, that just leaves double apex turns.  The apex of a trajectory is where the slope changes by passing from a positive slope to a negative slope.  When the slope is zero, that is the apex.  With riding the apex is actually a little more subjective.  The easiest way for me to think about it is like this.

You can divide up the turn into two parts -- the first part and the second part.  The first part is that section where the distance between you and the inside of the turn is decreasing.  The turn is getting tighter.  Once you pass the apex, the turn actually starts to open up again and the inside of the road starts moving away from you.  After you pass the apex, you can begin to see further down the road than you could before -- that's what riders mean when they say "the road opened up." 

Watch racers on the track and if you measure that distance to the inside of the turn, you'll be able to mark the apex points of each turn.

So, what is a double apex?  Turn 7 at I/SP is a great example.  If you look at the turn, it's actually in the shape of a square U.  Rather than being a nice, constant radius turn, the turn apexes early then starts to open up for a few feet before you have to tighten up your line again to hit a second apex before hitting the next straight.  It's like having two turns in one but you never really get to put your bike vertical in between.  With double apex turns, you usually have to adjust your lean angle during the turn to make the second apex.

So what does this have to do with the rear brake?  On lefthand, double apex turns, I can use my rear brake to initiate that change for the second apex.  Again, this is something I learned in Freddie Spencer's Sport Rider II class.  I'm not sure it has much application on the street but it's something to think about, I guess.

My brain hurts. 

Cheers,
Chip
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so does mine...

[Matt]

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so does mine...  
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Sheesh, mine too. Nice one Chip.

--matt

[Kensaku]

So, what is a double apex?  Turn 7 at I/SP is a great example.  If you look at the turn, it's actually in the shape of a square U.  Rather than being a nice, constant radius turn, the turn apexes early then starts to open up for a few feet before you have to tighten up your line again to hit a second apex before hitting the next straight.  It's like having two turns in one but you never really get to put your bike vertical in between.  With double apex turns, you usually have to adjust your lean angle during the turn to make the second apex.
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Hey Chip - do you take T7 wide (i.e. enter wide and hit the second apex) or do the double-apex thing? I've noticed people do both and I've tried both and I don't know which is better. Last time Tim (snoggin) showed me the wide version but he told me he has since started to take the traditional double-apex path. It seems that double-apexing is faster but a little more mechnically involved, which doesn't necessarily make it a bad thing, but what are your opinions on taking T7 wide?

Thanks.

[Waterboy]

Chip, you get an "A!"

[Chip]

Hey Chip - do you take T7 wide (i.e. enter wide and hit the second apex) or do the double-apex thing?  I've noticed people do both and I've tried both and I don't know which is better.  Last time Tim (snoggin) showed me the wide version but he told me he has since started to take the traditional double-apex path.  It seems that double-apexing is faster but a little more mechnically involved, which doesn't necessarily make it a bad thing, but what are your opinions on taking T7 wide?

Thanks.
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I adjust my entrance to T7 depending on the situation and I've seen fast people round off the square but still hit both apexes but going deeper in the middle. When racing, if you go deep on the entrance of a turn, then you're opening yourself to get stuffed on the inside so I don't see a wide entrance that much unless someone overshoots or gets pushed out by traffic.

What I tend to do is to convert the double apex into more of a dog leg. The most important part of T7 is the second apex because it opens up onto a fast section of track. The first apex, just gets you to the second apex. By squaring off the second apex and hitting it on the back side, I'm actually pointed more down the straight so I can take away lean angle sooner. I don't always get it right though and sometimes I end up just rounding both apexes.

If you want to talk about track cornering some more, maybe we should start a thread over on the "Riding Techniques for the Track" section.

Cheers,
Chip

[acme rider]

Chip... that boy's got some smarts. You been schooled reeeeaaal goooood in this stuff!

Seriously... I've never met anyone with more intellectual knowledge of riding. Thanks for all the great information. Personally I really want to focus on tecnnique this summer. I think we should setup a group ride where we consciously pick an area we all want to improve on and focus on that for the entire ride. I know Dan (Bronze) suggested a lecture before but I think if we had a quick briefing followed by sharing feedback with each other during the breaks... I know for myself, I would benefit greatly!

Now if I could just remember this stuff while I'm riding instead of.... "beer...... donuts....... beer....... donuts....... beer....."

[DMc]

Trail braking has good points and bad points. I stumbled into this thread that had some good info:
http://www.southbayriders.com/forums/showthread.php?t=12327

[Kensaku]

Trail braking has good points and bad points. I stumbled into this thread that had some good info:
http://www.southbayriders.com/forums/showthread.php?t=12327
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Stop stirring the poo pot.

[DMc]

One thing about the intraweb. Everybodies got an opinion

[Chip]

Trail braking has good points and bad points. I stumbled into this thread that had some good info:
http://www.southbayriders.com/forums/showthread.php?t=12327
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I think that's a pretty good thread. I agree with the MSF not teaching trail braking -- enough is being taught in there already -- but I also agree that a rider's education should not stop there. I think I've already said this but I'll say it again; Trail braking is an advanced technique but it's not that hard, really. The key is to have mastered a decent level of riding experience and good habits.

I have also noticed that some people talk about trail braking and they don't really know what they're talking about -- present company excluded. There is a speed where trailbraking isn't very useful or effective -- you're just going too slow. Trailbraking is also definitely more useful if you're going fast -- it extends your braking zone. However, I will often trail my brakes with the lightest of touch just to keep a little more lload on the front wheel -- the take some slack out of the front suspension, so to speak. I don't really need the brakes at that point but it works for me, it's a habit and it's a safety precaution to keep me from reaching out and grabbing brakes if something surprises me in the turn.

If you're a new rider, worry about braking while you're straight up and down first and be conservative with your turns. As you are more comfortable with riding, the bike, etc., practice keeping a little brake -- just the least amount -- on while you're turning but watch your lean angle.

Cheers,
Chip

[DMc]

Ive been thinking about how I enter turn at a good pace and trail braking is very natural for me.
The problem is you have to be going pretty fast inorder for it to be practiced with any effect. That is why I don't think nubbies should be doing it. In a car the debate is the same. Turn one @ T-hill is a good example of where I would use it in a car. At the end of the straight you are carrying a bunch of speed. Late and hard braking is the way to enter that turn and trail just a bit to the apex. Then floor it once the wheels are staight.




Ohh post count +1 Tom I will be fourth before this day is out

[Nep-Toon]

that's a lot to digest, that double apex turn. I guess it kinda makes sense. Maybe one day i will actually understand all of that stuff. And what is Euclidean geometry ? is that just a fancy term for 3d?

[Chip]

that's a lot to digest, that double apex turn. I guess it kinda makes sense.  Maybe one day i will actually understand all of that stuff. And what is Euclidean geometry ? is that just a fancy term for 3d?
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As I understand it, Euclidean geometry comprises 2d and 3d geometry -- real world stuff. Non-Euclidean geometry is the stuff that make my head hurt.

All in good time, grassahopper.

[DMc]

Wednesday night I'll bring a couple copies of a DVD I produced for Auto Track days. There is a section that talks about the "Late Apex" and setting yourself up for turns. It's for cars mind you but alot of the dynamics are the same.

[snoggin]

Wednesday night I'll bring a couple copies of a DVD I produced for Auto Track days. There is a section that talks about the "Late Apex" and setting yourself up for turns. It's for cars mind you but alot of the dynamics are the same. 
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From what I understand , most of the fast guys at the track trailbrake into just about every turn. One thing I haven't seen mentioned here and the new people should know is if you try this be very careful as some bikes have a major tendency to stand up when the front brake is applied in a turn. I think it has to do with suspension setup and geometry. Chip? Start very easily and see how your bike reacts to this technique before going into a turn hot.

[Chip]

From what I understand , most of the fast guys at the track trailbrake into just about every turn.  One thing I haven't seen mentioned here and the new people should know is if you try this be very careful as some bikes have a major tendency to stand up when the front brake is applied in a turn.  I think it has to do with suspension setup and geometry.  Chip?  Start very easily and see how your bike reacts to this technique before going into a turn hot.
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Tim, I thought I had mentioned the bike standing up when brakes are applied but that must have been the other braking thread. You're absolutely right, though -- if you are floating through a turn without any brakes and you apply brakes mid turn, two things are likely to happen.

• The bike will attempt to stand up and go straight. They demonstrate this in one of the MSF courses.
• You can apply an abrupt, instanteous force to the front tire causing it to exceed traction and you low side.

Bike suspension setup and geometry influence this behavior but you can't fix it with suspension or geometry changes, it's built into the design and physical limits of the bike and tires.

The key with trailbraking is to carry some brake pressure into the turn and then you can modulate it if you need. If you force a surprise, mid-turn stop the bike will still want to stand up but it will be more controlled. If you want to just slow down a hair because someone just took your line (e.g. at the track) or a slow car appeared in front of you (e.g. on the road) you can just squeeze a little more.

As Tim and DMc have pointed out, the most important thing to learn first is SMOOTHNESS! Be smooth with the brakes, be smooth with the throttle and keep your weight off the handlebars by using your lower body. If you have too much weight on the handlebars or are abrubpt with the brakes leading in or the throttle coming out, you will pay the price. Bikes will reward you when you're smooth.

If you start experimenting with trailbraking, start with the lightest touch you can on your lever and progress from there. Grab too much brake for your traction (which is less in a turn) and you're going to dump yourself on your ear.

Cheers,
Chip