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Trail Braking---not That Fastest Way, But They All Do It


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Oh, great post, Carl.

 

I'll reply when I have a bit more time.

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The bottom line is that while being on the brake may steepen the steering angle, it also increases stress on the contact patch reducing traction and, by defnition, dictates a slower entry speed and slower, not quicker, turn-in in with a more shallow entry line. And, in most circumstances, I believe the goal you describe can be accomplished with more efficient techniques that have been discussed at some length here.

 

racer

 

IMHO, adding more load to the front wheel doesn't necessarily reduce traction. For maximum *potential* of quick turning, you need as much vertical force on the front as you can apply, to get maximum traction for the fast steering input. The issue with breaking is that while it does transfer weight to the front, it also applies backward force on the tire (well.. that's what breaks are for afterall) which is consuming valuable traction resources which are needed for the steering action.

 

Perhaps what trail breaking contributes is adding this extra weight on the front which cannot be achieved otherwise (consider a rear BP and it's contribution to weight distribution while approaching a turn at a fixed entry speed without using the breaks). As an exaggeration of this technique, imagine the amount of vertical force applied to the tarmac during a very balanced rolling stoppy with no breaks, which still consumes zero traction resources (no lateral force applied to the tire).

 

So the break is released right on entry exactly for reducing this lateral force, but the weight distribution might still be more forward than a natural one, therefore allowing to apply more force for the steering input because more traction is potentially there. It's kept slightly on though to prevent the offloading of front fork after the spring decompresses, and not necessarily for the extra breaking force at the beginning of the turn.

 

Personally though, although I still steer relatively slow, I do find that keeping the break lever feathered on entry prevents the front from offloading on releasing the break. The other option is break, release, wait for the front to stabilize after possibly offloading it, start turning. With the breaks, it's just break, release 95% of the breaking force while keeping 5% to prevent offloading, start turning while releasing the rest 5%. I might be wrong, but I feel that it saves a lot of time on entry over a technique at which you completely release the breaks before applying the steering input, due to the required stabilization period.

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Didn't Keith write about releasing and doing a quick turn "before" the suspension had a chance to rebound? I also think I remember him writing in a post above about matching the final brake force to the force that the quick turn would put on the front end so the suspension would remain stable. That's substantially different from letting the front end rebound and stabalize before turning in (and why I mentioned his method was "almost" trail braking in my mind).

 

As to getting or reducing traction by loading the front end. I'm finding loading a wheel can increase grip some (spreading the contact patch a bit and driving the tire down into the texture of the road some will increase grip)..... until it doesn't...... then it reduces traction from overload. As with most things in riding, there seems to me to be a sweet spot to find with most stuff.

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The bottom line is that while being on the brake may steepen the steering angle, it also increases stress on the contact patch reducing traction and, by defnition, dictates a slower entry speed and slower, not quicker, turn-in in with a more shallow entry line. And, in most circumstances, I believe the goal you describe can be accomplished with more efficient techniques that have been discussed at some length here.

 

racer

 

IMHO, adding more load to the front wheel doesn't necessarily reduce traction. For maximum *potential* of quick turning, you need as much vertical force on the front as you can apply, to get maximum traction for the fast steering input.

 

Mmm... not quite.

 

"For maximum potential of quick turning", you need *some* weight or vertical force on the front wheel. As you allude, when applied with skill, the front brakes are powerful enough to lift the rear off the ground without a loss of traction at the front. Clearly, that is too much vertical force on the front for maximum *potential* quick turning.

 

Also, the key here is vertical force in that once you begin to lean the bike over, the added lateral force negates the whole "bigger contact patch" deal. If you think through the "bigger contact patch" deal... once you begin to lean the bike, that "vertical force" is no longer vertical and the "bigger contact patch" due to vertical force created by braking shrinks in direct proportion to lean angle.

 

So, if one is carrying enough speed to be at maximum traction upon quick turn, that is on the verge of sliding or "pushing" the front at the turn point (which is the goal of a really fast rider... by definition, maximum speed), adding brake force/stress on top of the lateral cornering force/stress must reduce traction and dictate a slower speed.... or, obviously, you will lose the front.

 

Like Carl alluded, once you lean over, being on the brake is a game of diminishing returns.

 

 

Personally though, although I still steer relatively slow, I do find that keeping the break lever feathered on entry prevents the front from offloading on releasing the break.

 

Yes it does. But... could that be because you "still steer relatively slow"? Turn-in and cornering force will compress your suspension far more than braking (attach a zip-tie to your fork leg if you wish to test this theory). Can timing your turn-in at the moment of brake release accomplish the same thing?

 

The other option is break, release, wait for the front to stabilize after possibly offloading it, start turning. With the breaks, it's just break, release 95% of the breaking force while keeping 5% to prevent offloading, start turning while releasing the rest 5%. I might be wrong, but I feel that it saves a lot of time on entry over a technique at which you completely release the breaks before applying the steering input, due to the required stabilization period.

 

Exactly... "due to the required stablization period". The period of time it takes the suspension to rebound. If you feel that period of time is big enough to cause a slower lap, is it big enough to fill with turn-in force?

 

And what about using your body to alter COG? Can using your body position to alter your COG and f/r weight distribution in conjunction with a rate of deceleration that is already weighting the front without the brakes create enough weight on the front wheel for a sharp and quick turn in? Don't forget, simply rolling off the gas transfers a significant amount of weight to the front wheel. And, if at the moment you lean into the turn, the cornering force brings you to max traction and you are pushing the front, trailing the brake is a very risky game that takes a lot of attention.

 

Bottom line, IMHO, if your sense of speed and traction isn't good enough to be confidently pushing the front at will without the brakes as a matter of normal course (*yawn* I slid the front ten feet into that turn *yawn*) or you "still steer relatively slow", using the brakes will, in 90% of the cases, overpower your attention and sense of speed and traction causing SR's and your entry speed to be too slow and your line to be too shallow (on top of an already shallow line due to "still steering relatively slow") ... and THAT is the final point.

 

IMHO, if you aren't already at the level where you can pretty much push the front at will without the brakes, you aren't really ready to be playing with trailbraking as a standard skill to go faster outside of standard trailbrake situations like a DR turn. You will only slow yourself down, limit your learning curve and stunt the development of your sense of speed and traction.

 

racer

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Yes it does. But... could that be because you "still steer relatively slow"? Turn-in and cornering force will compress your suspension far more than braking (attach a zip-tie to your fork leg if you wish to test this theory). Can timing your turn-in at the moment of brake release accomplish the same thing?

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I'd consider your proposal as a form of trail breaking as well. Timing the release of the breaks such that the turn-in point happens after the release but just before the front offloads is a delicate task, and IMHO not easier than the technique I've described. Basically, if I understand you correctly, what you suggest is more or less what I've described, but refined for better result and which requires better control and timing.

 

Regarding the rest of your post, there's a good chance you're right about getting first thing first and leaving trail breaking as a more advanced technique to master. So yes, I always listen and try to learn and improve, and putting that kind of entry aside might be the thing to try. Still, and possibly because I'm still far (I think) from flicking the bike fast, it does give me a better feel to keep touching the breaks very lightly on entry.

 

I need track time :)

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Yes it does. But... could that be because you "still steer relatively slow"? Turn-in and cornering force will compress your suspension far more than braking (attach a zip-tie to your fork leg if you wish to test this theory). Can timing your turn-in at the moment of brake release accomplish the same thing?

...

I'd consider your proposal as a form of trail breaking as well. Timing the release of the breaks such that the turn-in point happens after the release but just before the front offloads is a delicate task, and IMHO not easier than the technique I've described. Basically, if I understand you correctly, what you suggest is more or less what I've described, but refined for better result and which requires better control and timing.

 

No. Not at all. Trailbraking is defined as continuing to brake during and after turn-in.

 

It was not my intention to recommend a specific technique in the paragraph of mine you quote above. I was thinking about and asking question(s) about what Carl suggested Keith has written wrt to timing turn-in after releasing the brake and before the suspension can rebound, ie. considering it might essentially be using cornering force itself to counter the rise of the front suspension after coming off the brake.

 

Also, I was asking you to consider if "still steering relatively slow" might be a part of the issue wrt relying on the brakes to do something other than slow down. For instance, while it takes the average street rider about one second or even more to lean a motorcycle into a turn, a fast rider does it in about one quarter of a second. Not much braking gets done in a quarter of a second, eh?

 

As I said above, IMO, smoothly letting off the brake lever to control the rise of the front suspension is definitely a valid and useful skill. However, doing it while turning-in is an exceptionally delicate, complex and risky operation when at or near the limit of traction already. While timing your flick as close as possible to your brake release point may seem more "delicate" or more precise than trailbraking to you, trust me, it really isn't. Trailbraking involves balancing several limits at once, while letting off the brake first reduces that number. And it's an inherently less risky proposition that would result in more available traction... which would lead to higher cornering speed, of course.

 

Please bear in mind I am trying to approach this subject within the parameters of the thread title which questions whether or not trailbraking (as a standard technique for every turn) is the fastest way around a race track. Not what feels easier. And that is a point that Keith covered here (in this thread, I think).

 

The point: being on the brake feels comforting and reassuring. It gives the rider a way to feel in control of the situation throughout the process. "Easing their way into it...", as Keith said. Feeling the traction each and every millimeter of the way through the brake lever and being able to react by modulating the brake lever to compensate for any impending loss of traction as opposed to relying on their sense of speed and just "throwing it in" and "hoping for the best" with no way out, nothing to do if the front slides... except gas it more! I imagine that the front brake lever and trailbraking may become a very real "security blanket" that many riders resist letting go of.

 

In any case, how much compression does the fork really need to effectively quicken the steering? And is it possible to achieve that compression without sacrificing traction or potential flick speed the way that trailbraking does? Long and low? Kiss the mirror? Hook turn?

 

As I said above, rolling off the throttle will compress the suspension and weight the tire enough for flicking all by itself. And changing your body position to alter your center of gravity can amplify that advantage. In my opinon, carrying a higher entry speed while off the gas with the proper body position is more effective and efficient than turning-in and entering on the brakes for most turns.

 

 

Regarding the rest of your post, there's a good chance you're right about getting first thing first and leaving trail breaking as a more advanced technique to master. So yes, I always listen and try to learn and improve, and putting that kind of entry aside might be the thing to try. Still, and possibly because I'm still far (I think) from flicking the bike fast, it does give me a better feel to keep touching the breaks very lightly on entry.

 

Exactly. You said it all. It gives you a better feel.

 

 

I need track time :)

 

Don't we all!! :P

 

Get Keith's books and take the schools. There is no substitute.

 

 

Sincerely,

 

racer

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  • 5 months later...
From my experience, there are some turns that you really have to trail into to maintain your speed, Turns 3 and 9 at Fontana are good examples. In general, I try not to, but once in a while I don't see a way around it.

 

 

I agree, these corners would be good candidates for trail braking. In turn three your kinda leaned over going in there and it is closely followed by another corner. Turn nine is closely followed by another corner as well.

 

I'm not sure if maybe it was mentioned earlier in this thread, but to me any corner that leads into another corner can be a good candidate for trail braking. Mostly because I feel that getting into such corners fast is more important then getting a drive our of them or getting on the gas super early. As always there are exceptions, but it works for me as a rule of thumb.

 

If a corner is followed by a straight you need to think about your exit speed more. In these corners trail braking probably isn't such a good idea.

 

Like at Willow Springs, trailing the brake into turn three works OK, but I wouldn't trail brake into turn one.

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I agree, these corners would be good candidates for trail braking. In turn three your kinda leaned over going in there and it is closely followed by another corner. Turn nine is closely followed by another corner as well.

 

I'm not sure if maybe it was mentioned earlier in this thread, but to me any corner that leads into another corner can be a good candidate for trail braking. Mostly because I feel that getting into such corners fast is more important then getting a drive our of them or getting on the gas super early. As always there are exceptions, but it works for me as a rule of thumb.

 

If a corner is followed by a straight you need to think about your exit speed more. In these corners trail braking probably isn't such a good idea.

 

Like at Willow Springs, trailing the brake into turn three works OK, but I wouldn't trail brake into turn one.

 

Very long late apex decreasing radius turns are what comes to mind for single turns.

 

C

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  • 3 weeks later...
I agree, these corners would be good candidates for trail braking. In turn three your kinda leaned over going in there and it is closely followed by another corner. Turn nine is closely followed by another corner as well.

 

I'm not sure if maybe it was mentioned earlier in this thread, but to me any corner that leads into another corner can be a good candidate for trail braking. Mostly because I feel that getting into such corners fast is more important then getting a drive our of them or getting on the gas super early. As always there are exceptions, but it works for me as a rule of thumb.

 

If a corner is followed by a straight you need to think about your exit speed more. In these corners trail braking probably isn't such a good idea.

 

Like at Willow Springs, trailing the brake into turn three works OK, but I wouldn't trail brake into turn one.

 

Very long late apex decreasing radius turns are what comes to mind for single turns.

 

C

 

 

WOW, I just read all 5 pages on this trail braking tread. Can't believe it started 1 1/2 years ago!! Could it be that if you put a top Moto GP racer on the track by himself and said go run some fast laps, that the amount of trail braking would be a lot less then if it was a race situation? Adrenalin and competitiveness makes you push a lot harder, sometimes too hard into corners, when you have to trail brake. That doesn't mean it's the fastest way around the track it just means it was the only way to get the job done at that moment. To use Keith's saw/house building comment from a few pages ago. Lets say I'm building a house, and I'm up on the roof, and I need to cut one 2 x 4. My choices are go down to the truck, plug in the extention cord, haul it up on the roof, plug in my saw then cut the board. Or I could just use the hand saw that is on the roof and is available. The power saw is faster, except when it's not. To me the quick turn and trail braking are just tools that should be used when the time is right, not all the time or none of the time. Just my 2 cents.

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