Trail braking

[glib]

I watched a couple YouTube vids on trail braking and I’m trying to figure out when it would really be useful. One said all the time but since they are using the front brake going into turns “trailing” off the lever after the pressure of the brake has increased the contact patch of the front tire, I dont see it useful in the twisties because the front brake—even light pressure—sits me up. The rear brake pulls me down into the turn and seems especially helpful if I’ve entered a bit too hot. The video said it was dangerous to use rear brake in a turn and showed a guy run into the guardrail but it looked exactly like he used front brake and lifted out of his lean.

So so I understand the explanation of the technique but it feels counterintuitive in practice. I am thinking maybe better on the track?

[Buffalo Bill]

You're right to adjust this advice for your bike's reaction to it. Different bikes respond in different ways. Plus a most of riding advice is dumbed down for novice rider's safety.
On the track but not racing, trail braking is my last resort fix for an off line entry.
In racing it's a tactic for maintaining maximum speed until the last possible instant.
The sit up effect is different depending on the bikes rake angle and weight distribution. The GS has a mild rake angle and trail plus high weight, sport bikes have a steep rake, shorter trail and low weight.
Using the rear brake is fine and good on the track 'cept you have to move your right toe out to the peg end for right turns. It can be used for left turns.
Me on the track, I only use the rear brake before corner entry, and keep my right and left turn technique symmetrical. I trail the front brake lightly.
Public roads are so unpredictable, I never get closer than 30% of race track intensity.

[RichDesmond]

Trail braking is method of exploiting the traction available at the tires in the most efficient way possible. A useful concept from car racing is the "friction circle" or "traction circle". It doesn't carry over completely to bikes, but it's good to understand the concept.

https://virtualracingschool.com/academy/iracing-career-guide/second-season/the-traction-circle/

So, what we're trying to accomplish in trail braking is travelling around the friction circle, as close to the perimeter as we can get. When you first hit the brakes for a corner, it's not too hard to get the tire right on the edge of lockup. At that point you can't turn the bike at all, because you're using all the available traction and if you introduce a side load you exceed the tire's capability. You could let off the brake completely and then snap the bike over to max lean. Two problems with that. First, there's that transition time where you're not utilizing most of the available traction. Second, you're porpoising the bike on the suspension, the front end rising as you let off the brake and then compressing as the lean angle increases. That varies the load on the tire, and with that the traction.
What you want to do instead is let off the brake at about the same rate that you're increasing the lean angle. That way you're travelling around the perimeter of the circle, not wasting traction that's usable and keeping the front suspension compressed roughly the same amount.
On the track, the practical consequence is that you can brake much deeper into corners since you don't have to have all the speed scrubbed off at the turn-in point. Also run a bit more lean angle since you've been smooth on entry and the chassis and suspension aren't upset.
Important to realize that if done correctly, you are always releasing pressure on the brake lever throughout this process, never increasing it. If you do have to increase braking, perhaps you get cut off or someone crashes in front of you, then you also have to stand the bike up a bit to keep the sum of the forces below the traction limit.

That's all well and good on the track, but what about the street? There, IMO, the technique is a lot less useful. There's a lot of risk in feeling your way to the outer parts of the forward quadrant, if you go over the line the front folds and you crash with little to no warning. (unless you're Marc Marquez ) If I'm riding at a brisk pace I do it a little, mostly to keep the suspension settled. I don't have much interest in exploring that part of the traction envelope on the street. I do maintain just a bare amount of pressure on lever all the way to the apex. That makes it easier to be very smooth in increasing braking mid-corner if there's a need to.

I never, never use the rear brake when riding fast. Much too difficult (for me at least) to modulate it effectively.

As for "entering too hot", most street riders end up in that predicament because they're on the wrong line, usually a too-early turn-in point, especially on left handers. If that's happening to you more than extremely rarely you need to figure out why.

[glib]

Excellent answers. I feel a bit better--except that I cover the rear brake quite a bit and find that it takes very little pressure to help me get leaned down in a corner. My rear brake is not very sensitive so there's that. I'm not worried about locking it up with a little pressure. Getting too hot in a turn for me usually involves back to back twisties with one being significantly tighter than the others.

In a recent ride, a friend slid off into the gravel after going too hot into a corner. It was a left turn immediately after a right and I don't see how trail braking could have helped at all. I think using the front brake is what put him to the outside of the turn and ultimately in the gravel. I believed at the time that a light touch of rear brake would have gotten him around the corner safely. Don't want to be giving bad advise though.

[RichDesmond]

Excellent answers. I feel a bit better--except that I cover the rear brake quite a bit and find that it takes very little pressure to help me get leaned down in a corner. My rear brake is not very sensitive so there's that. I'm not worried about locking it up with a little pressure. Getting too hot in a turn for me usually involves back to back twisties with one being significantly tighter than the others.

In a recent ride, a friend slid off into the gravel after going too hot into a corner. It was a left turn immediately after a right and I don't see how trail braking could have helped at all. I think using the front brake is what put him to the outside of the turn and ultimately in the gravel. I believed at the time that a light touch of rear brake would have gotten him around the corner safely. Don't want to be giving bad advise though.

Quick transitions like you describe are a really easy place to get it wrong. Run a bit wide on the exit of the first turn and you're way off line for the second, a bit like turning is too early, only worse. The key to sequences of corners like that is to use very late apexes on all the turns except the last.

A little front brake would have helped your friend more than the rear, IMO. As soon as he realized he was in trouble he should have tried to scrub off some speed, the best way to do that is using a little front brake and lifting the bike just enough to give you the traction needed to keep the brake on. How much brake, how much lift, that depends on the exact situation.
I don't agree with using the brakes to adjust lean angle. I do that mostly with countersteering, a little with weighting of footpegs. Brakes are for losing speed. I know how the bike is going to react to the brakes, and then use the proper technique to keep the lean angle where I want it.

[Buffalo Bill]

The key to sequences of corners like that is to use very late apexes on all the turns except the last.

I wonder if that would work at Grattan Michigan through the ZZs?
See 0:47 through 1:09.

[RichDesmond]

I was really just referring to street riding.
On the track, you work backwards. By definition, the last corner in a sequence leads onto a straight, so the critical thing is exit speed out of that last turn. So you figure out right line for that, and the line for turn before that feeds into that line and keep going backwards until you're at the straight where the whole sequence started.
Typically you end up with later apexes on all but the last turn, but not always.
This is also why chicane entrances are good passing zones, because the fastest line usually involves a wide entry.

[hannibal]

I was going to ask for your definition of trail braking. I always considered trail braking as braking into the corner as opposed to braking before turning into the corner.

The traction circle that Rich posted seems to agree with my initial idea, but goes far deeper in explaining the concept. Super awesome description of the trade offs in braking and cornering!

[glib]

Quick transitions like you describe are a really easy place to get it wrong. Run a bit wide on the exit of the first turn and you're way off line for the second, a bit like turning is too early, only worse. The key to sequences of corners like that is to use very late apexes on all the turns except the last.

A little front brake would have helped your friend more than the rear, IMO. As soon as he realized he was in trouble he should have tried to scrub off some speed, the best way to do that is using a little front brake and lifting the bike just enough to give you the traction needed to keep the brake on. How much brake, how much lift, that depends on the exact situation.
I don't agree with using the brakes to adjust lean angle. I do that mostly with countersteering, a little with weighting of footpegs. Brakes are for losing speed. I know how the bike is going to react to the brakes, and then use the proper technique to keep the lean angle where I want it.

Im pretty sure this ends up a reflection of my lack of experience (you nailed it on the early entry to left handlers) but just so I’m clear about my friend going down, here is what I pictured. He is pushing himself (as I might more cautiously do), it’s slightly downhill and he realizes, already leaning in, that he is too hot and hits the front brake reducing his lean which sends him to the paint and then the gravel. Maybe if he was skilled with trail braking but he had told me previously that he lightly pumps the front brake to slow in the corner. Bad idea to my mind but even with a gentle touch I still don’t see how, once in the corner with lean initiated, the front brake could have helped whereas the rear would have slowed him and pulled him deeper into the lean allowing him to avoid the gravel. Trail braking needs to begin while upright and trails off to the apex correct? Seems like a finely tuned strategy rather than an adjustment in the turn. BTW, on a previous ride he had a pucker event with a decreasing radius turn and barely avoided gravel using the front brake.

Again, I’ve never been on the track and lots of these turns are blind so you don’t know exactly where the apex is (you did mention that the technique would be less useful on the street) and the rear brake works for me but I’m concerned about developing a bad habit.

[solarae]

https://youtu.be/gPE67XqGsV4

[RichDesmond]

Im pretty sure this ends up a reflection of my lack of experience (you nailed it on the early entry to left handlers) but just so I’m clear about my friend going down, here is what I pictured. He is pushing himself (as I might more cautiously do), it’s slightly downhill and he realizes, already leaning in, that he is too hot and hits the front brake reducing his lean which sends him to the paint and then the gravel. Maybe if he was skilled with trail braking but he had told me previously that he lightly pumps the front brake to slow in the corner. Bad idea to my mind but even with a gentle touch I still don’t see how, once in the corner with lean initiated, the front brake could have helped whereas the rear would have slowed him and pulled him deeper into the lean allowing him to avoid the gravel. Trail braking needs to begin while upright and trails off to the apex correct? Seems like a finely tuned strategy rather than an adjustment in the turn. BTW, on a previous ride he had a pucker event with a decreasing radius turn and barely avoided gravel using the front brake.

Again, I’ve never been on the track and lots of these turns are blind so you don’t know exactly where the apex is (you did mention that the technique would be less useful on the street) and the rear brake works for me but I’m concerned about developing a bad habit.

First off, I'll say that I wasn't there and didn't see it happen, so I'm just doing uninformed speculation...

That said, based on your description, there's a few red flags here.
First and foremost, we have a pattern of getting in too hot. If that happens more than once a decade you're riding beyond your skill level and need to slow the f^ck down until your speed matches your skills. If you want to go faster, improve your skills.

Pumping the brake mid-corner. Hard to think of a worse strategy. Loading and unloading the tire, unsettling the suspension, if you want to crash that's a good way to go about it. What I do, from previous post; "I do maintain just a bare amount of pressure on lever all the way to the apex. That makes it easier to be very smooth in increasing braking mid-corner if there's a need to." I do that not because I'm trail braking to any meaningful extent, but because keeping that slight pressure on means the I've already taken up the free play in the brake system, and because it's smoother to transition from a small amount of pressure to a slightly greater amount. Going from nothing to something is always going to upset the bike more.

"already leaning in, that he is too hot and hits the front brake reducing his lean which sends him to the paint and then the gravel."
This makes me want to gouge out my eyes so I don't read this kind of stuff any more. So much wrong...
Mostly, the very late awareness that there's a problem. Then the confusion about vehicle dynamics. Points to a lack of judgement and skill. Also, likely target fixation.

Second, "hits the front brake". You NEVER "hit" the front brake. You squeeze it on, smoothly, controlling the rate at which weight transfers to the front and how much of your total traction you're using.

Third, "front brake reducing his lean". Lack of anticipation of what the bike's going to do in response to a control input. Most bikes will want to stand up in response to increased mid-corner braking. You have to know that in advance, and as you increase braking pressure you also increase pressure on the inside bar to keep the lean angle constant. (Assuming that that's what you want.)

"lots of these turns are blind so you don’t know exactly where the apex is"
Seriously?? This is known as "overriding your sight lines" and may well get you killed at some point. Not seeing the apex is the least of your problems and, as should be obvious, if you can't see it you stay wide until you can. Corner entry speed is predicated on what you can see. THERE SHOULD BE NO SURPRISES!!

I know all this sounds harsh, and I'm sorry about that, but you guys have some serious problems and I'd be remiss if I didn't point them out. Ride safe.

[glib]

First off, I'll say that I wasn't there and didn't see it happen, so I'm just doing uninformed speculation...

That said, based on your description, there's a few red flags here.
First and foremost, we have a pattern of getting in too hot. If that happens more than once a decade you're riding beyond your skill level and need to slow the f^ck down until your speed matches your skills. If you want to go faster, improve your skills.

Pumping the brake mid-corner. Hard to think of a worse strategy. Loading and unloading the tire, unsettling the suspension, if you want to crash that's a good way to go about it. What I do, from previous post; "I do maintain just a bare amount of pressure on lever all the way to the apex. That makes it easier to be very smooth in increasing braking mid-corner if there's a need to." I do that not because I'm trail braking to any meaningful extent, but because keeping that slight pressure on means the I've already taken up the free play in the brake system, and because it's smoother to transition from a small amount of pressure to a slightly greater amount. Going from nothing to something is always going to upset the bike more.

"already leaning in, that he is too hot and hits the front brake reducing his lean which sends him to the paint and then the gravel."
This makes me want to gouge out my eyes so I don't read this kind of stuff any more. So much wrong...
Mostly, the very late awareness that there's a problem. Then the confusion about vehicle dynamics. Points to a lack of judgement and skill. Also, likely target fixation.

Second, "hits the front brake". You NEVER "hit" the front brake. You squeeze it on, smoothly, controlling the rate at which weight transfers to the front and how much of your total traction you're using.

Third, "front brake reducing his lean". Lack of anticipation of what the bike's going to do in response to a control input. Most bikes will want to stand up in response to increased mid-corner braking. You have to know that in advance, and as you increase braking pressure you also increase pressure on the inside bar to keep the lean angle constant. (Assuming that that's what you want.)

"lots of these turns are blind so you don’t know exactly where the apex is"
Seriously?? This is known as "overriding your sight lines" and may well get you killed at some point. Not seeing the apex is the least of your problems and, as should be obvious, if you can't see it you stay wide until you can. Corner entry speed is predicated on what you can see. THERE SHOULD BE NO SURPRISES!!

I know all this sounds harsh, and I'm sorry about that, but you guys have some serious problems and I'd be remiss if I didn't point them out. Ride safe.

Sorry to make you want to gouge out your eyes but I was just painting a picture of what I thought happened.

Once I came over a hill and there was a big-ass calf in my lane. Running at me. That was a pretty legit surprise. Anyway, if I didn’t want your honest input I wouldn’t enter into the conversation. I have been trying to stay wide as I see others do. I have to fight the habit of hugging the inside of the turn.

I’ve been reflecting on whether I’m as bad as you make me sound. I wasn’t the one in the gravel you know. But I’ve been using the rear brake as a crutch in case I need to slow down mid turn—which is what motivated me to start this thread. So I tell the truth and deal with the feedback.

So thank you. I appreciate your candor and I will think about this on Sunday when I ride 26 with my son for the first time. I’d like to be a perfect example for him to follow—but I’ll have to do my best anyway.

[glib]

https://youtu.be/gPE67XqGsV4

That was one of the videos I watched.

[glib]

I wonder if that would work at Grattan Michigan through the ZZs?
See 0:47 through 1:09.

I want to do that.

Been trying to figure out what the indicator with the bouncing red ball is indicating.

[Buffalo Bill]

That's a G Level indicator. Looks like the instant read is too confusing and it's too sensitive, it should be re-set for a longer time span and less sensitive average.
Those readouts are for the crew engineers back in the pit.
Some coaches want tachs and speedos taped over, because they're distracting. The only place I can take a blink of time look at my tach and speedo is mid straight.
This track in Grattan Michigan, is diabolical, designed to X-up riders who think by the book, maybe the most technically demanding track in the Midwest.
What this video don't show is how blind the rider's vision is because of the steep up hills. Coming out of some turns I can only see 50 feet of pavement, and have to choose a line based only on memory and experience.
Mentioned by many advanced riders as their favorite.