| Author |
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Jlnance
| | Posted on Monday, December 05, 2005 - 06:37 pm: | 
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Thanks Anonymous. That makes sense. |
Steve899
| | Posted on Thursday, December 08, 2005 - 09:55 pm: |
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Blake, I think you won that parade lap. |
Blake
| | Posted on Thursday, December 08, 2005 - 11:01 pm: |
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Damn straight! No little kid is going to deprive me of MY glory!... However imagined it might be. ![: ]](http://www.badweatherbikers.com/buell/clipart/proud.gif) |
Pressureangle
| | Posted on Friday, June 09, 2006 - 09:24 pm: |
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There's so much to this question-so far I haven't seen any input which isn't valid, IMO. My suggestion is that you find a racetrack where you can get some time in an environment which is safe to study this.
That said; my personal opinion is that front wheel trail braking knowledge and practice is a life-saver on the street, but playing go-racer on the street with it is a sure way to ruined paint. Pay your money, take your shot. Anyway, it's vital to know how your bike likes trail braking-my S-2 racebike (in '98, very poorly set up) was horrid braking into corners. My 883 racers were every one the funnest tire squealing, rubber painting, front-wheel-sliding corner smokers on the planet. The big difference was that an 883 was biased towards oversteer at neutral throttle, so the back was loose before the front anyway-you could bury it in a corner, snap it to the pegs and nail the throttle while the back end was stepping out on the front braking. (sigh) Anyway, learn it but try to learn it where the penalty for miscalculation is minimal. Public roads are too unpredictable to use this technique very hard regularly.
YMMV. |
Josh_
| | Posted on Friday, June 09, 2006 - 10:15 pm: |
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Reg Pridmore's take is: "I didn't try it until Freddy Spenser talked it up with me.
Try it, if you like it, keep with it. But I don't suggest it in the wet."
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Rocketman
| | Posted on Saturday, June 10, 2006 - 05:16 am: |
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If you want to improve your braking skills on two wheels, and adapt that to trail braking, it's a most simple action to undertake and learn easily and safely.
Of course, no doubt there'll be some who see controversy in what I'm about to tell you, and Keith Code probably hasn't got a clue, so here goes.
Trail braking, or any other correct form of braking for a given circumstance is all about applied pressure.
Get in your car and go for a drive. At any time you feel the need to brake to a standstill, when you press the pedal do so so as the car doesn't dip, or dips no more than necessary until you reach the point where you want the car to stop. If at the very last moment, just as you let the brake pedal off, the nose of the car lifts up with a slight jerk or more, you were too heavy footed. Inch perfect and smooth glide type stopping is your aim. Imagine a glass of water on the 'hood'?? you don't want to be spilling a drop.
If you have this skill with your feet, or at least one of them, you now need to apply this same technique to your right hand when riding. Learn this well and you will find trail braking is all about two things. The feel factor and the applied pressure.
Learn the science on four wheels so as your brain understands the physics of interacting man to vehicle, then introduce the skill to two wheels and you'll soon get the hang of it, even when leaned over in a corner.
Rocket |
M1combat
| | Posted on Tuesday, June 27, 2006 - 12:14 am: |
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Another thing is that different tires react to trail braking differently. The original Dunlops would stand pretty hard when on the front brake. Not so bad with just dragging the rear a bit (I prefer this way). They weren't "too" bad when using the front while hanging off, but got worse as the lean angles increased. The Metzeler M1's and M3's I've used don't do this anywhere near as much but to be honest, I think that may be due to a setup more developed for street riding and my style.
I use the method where I just drag the rear brake and use everything on the front for rotation or avoidance (still rotation). I think anything that stands a bike in a corner can lead to bumper tasting. A very bad thing. That said... If you come into a corner hard and are on the front brakes, rear brakes, using some engine braking and "trailing" them off as you add lean angle (typically on a tightening corner where you need to stay outside longer but you're trying to "make time") you can use the brakes to help tune the lean angle. Namely, drop the bike in at the official "turn in" of a tightening radius turn by letting off the brake lever. You should then be getting on the gas soon because the apex goes by quickly.
If you have decent tires though (back to the street)... I've learned that the XB (even with my 200lbs on it) sticks to the road very well. After a while I just realized that if my toes aren't scraping I can lean over further. I stopped doing that when I started riding with the balls of my feet on the peg on the inside...
I suppose it all depends on your style. That said I pretty much agree with the posts that suggest practicing everything. I noticed that my front pads were getting a little thin so I just mostly quit using the front for a month or so until my rear pads were in need of replacement. I wasn't riding hard by any means, but I explored the feeling of the chassis at medium speeds. Once you know a corner is clean (NEVER assume) you can enter it on a normal line but outside a little, then just press the rear pedal very lightly and learn what will happen... Try a parking lot that's empty (and clean...) and just ease into it. I like to check the pavement first looking for any places that are slippery or more grippy. An addition of grip can also be bad. If you're sliding around just a bit and all of a sudden the front has more traction it can suprise you. Same with lines/cracks.
Anyway... approach it safely and carefuly. I say learn it, but be careful initially. |
Steve899
| | Posted on Tuesday, August 15, 2006 - 10:11 pm: |
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It is all about being Smooth ,I have heard it said Fast guys have slow hands. That is definitely true. |
Pressureangle
| | Posted on Wednesday, August 16, 2006 - 07:08 am: |
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3 - (a)Braking requires traction, which reduces the amount of traction available for leaning the bike.
(b)Thus if you could make it around the corner with the brakes applied, you could have made it around the corner by leaning further and not braking.
(a)False. Leaning doesn't require traction. OK, I'm nitpicking semantics here. Given good surface, traction isn't an issue until you are leaned pretty far over.
(b)False. This fails to account for the reduction in traction which accompanies a greater lean angle.
My responses to a and b seem diametrically opposed; it's important to know when you cross the point where available traction is less than necessary. Your bike won't skid the front tire while vertical, and it will still lift the rear tire before skidding while at significant lean angle (this and too much rear brake are responsible for a good percentage of highsides)but at some point, the front tire will skid before the rear lifts.
Closer to reality is to state that if you couldn't make it around the corner with no brakes, you probably wouldn't have with them either. I roadraced sportsters for years, and the front had so much traction that we modulated the entry slides with no rear brake at all; a bit more front brake, a bit more rear slide. That was usually very near the point where the footpegs were on the pavement. Bottom line is you have to know the road, and your bike.
I took Keith Code's Superbike school twice, in the '80s and own everything he's written. His training is pearl; but you have to pry open your own oyster to truly understand what he says. His writing is unclear and oblique. That said, you should read what he's written, slowly and carefully. Ass-u-ming consistent traction in a constant-radius turn, transitioning from brakes to turn to brake release should move the suspension very little. That is to say that once you've compressed the forks with the brake, they should stay compressed until you apply the throttle; this requires that you release the brake at a rate proportional to the g-force imparted by the turn.
There are a hundred ways to learn trailbraking-the racetrack is the best place. I learned it by beating a '74 KZ400 around the trails and dirt roads of Southeast Michigan.  |
Blake
| | Posted on Wednesday, August 16, 2006 - 12:38 pm: |
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Excellent stuff! May I add some more to the discussion. It is very interesting.
What fast smooth racers (like Steve899  ) do is use trail braking to allow later braking thus helping to pass competitors and/or achieve quicker laps times. There is a significant amount of time involved in transitioning between full on stood-up braking and full lean cornering at the apex. That significant amount of time required to achieve the transition to full lean allows for continued application of the brake(s).
An expert racer, Sam McDonald, father of young AMA racer Tyler McDonald instructs new CMRA racers that when racing, one should always either be on the gas or on the brakes, never just coasting; braking all the way to the apex, accelerating away from the apex. Yes very lightly and in a smooth controlled variable manner. Like our resident CMRA Expert Racer Steve899 advises.
MotoPhysics question:
When trail braking, available traction is consumed by the combined total of cornering and braking acceleration forces (g-forces).
If cornering (turning while leaned over) is consuming 80% of the total available traction g-force, what percentage of the total traction g-force is then left available for braking?
Hint #1: The answer is not 20%.
Hint #2: Anony already educated us on this.
I think good advice is to never plan on trail braking on a public road as a matter of course. Reserve it for panic situations. Take it to the track to learn and practice, or an open parking lot as M1 suggests. |
Jlnance
| | Posted on Wednesday, August 16, 2006 - 01:04 pm: |
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Blake: 202 + x2 = 1002
I'm glad to see this thread getting some more traffic. I did a thousand miles this weekend in the mountains. I'm convinced trail braking is a skill I need to master. The idea of braking before the turns is all well and good. But there are just too many times when you're behind someone else and they brake in the turn. Then you're sort of stuck. There was one curve this weekend. We weren't going that fast because it was blind. But it ended up being about a 300 degree turn. So it took a long time and I was leaned over reasonably far. I was running up on the bike in front of me, and starting to decide if it was better to try the brakes or cross the double yellow. Fortunately, m2nc moved over about then. But I don't like situations like that and I want more options for getting out of them. |
Bigdaddy
| | Posted on Wednesday, August 16, 2006 - 02:49 pm: |
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Jim,
We'll practice,,,,soon too. Just scored me a new contract in RTP. Look for the black Uly @ the same hotel :-)
G2 |
Blake
| | Posted on Wednesday, August 16, 2006 - 04:03 pm: |
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Jim,
Good approach, but check your numbers. |
Steve899
| | Posted on Wednesday, August 16, 2006 - 10:44 pm: |
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Jim, I know I sound like a broken record, but, if you want to learn TrailBraking there is only one way I know of to do it. The Track, it allows you to go through the same turn again and again, it is this repetition that teaches you,and trailbraking is not the only thing you learn. The street simple can't offer you that much repetition, good luck Jim. |
Crashm1
| | Posted on Friday, August 18, 2006 - 02:35 am: |
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} |
Crashm1
| | Posted on Friday, August 18, 2006 - 02:38 am: |
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Well that sucked I had this nice follow up post and it disappeared. I'll try again tomorrow.  |
Blake
| | Posted on Friday, August 18, 2006 - 01:25 pm: |
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I hate it when that happens! Have considered many times implementing a keystroke logger. I feel your pain. |
M1combat
| | Posted on Wednesday, September 20, 2006 - 08:09 pm: |
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.8x.8=.64
.6x.6=.36
.64+.36=1.00
.7x.7=.49
.71x.71=.5041
.49+.5041=99.41%... Not fast enough for qualifying...
.2x.2=.04
.98x.98=.9604
.04+.9604=100.4%... Probably just right . |
Blake
| | Posted on Thursday, September 21, 2006 - 07:45 am: |
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You got it!
"If cornering (turning while leaned over) is consuming 80% of the total available traction g-force, what percentage of the total traction g-force is then left available for braking?"
0.802 + x2 = 1.00 so...
x = (1.00 - 0.82)1/2
x = 0.6 or 60%
Not sure what the rest of your numbers are showing, the progression of trail braking to full lean at the apex? |
Berkshire
| | Posted on Monday, December 11, 2006 - 09:10 pm: |
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I think the other numbers are mapping out the edge of the traction circle - aside from an 80/60 split, you could go 71/70 or 98/20. It could apply to braking in to a corner or accelerating out. |
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