Trail braking

[glib]

Well, I was responding to your description of your friend's event.

Riding well and safely takes effort, concentration and practice. I raced for a very long time and all that time at the limit let me hone skills and habits that aren't second nature for a street rider. They certainly weren't for me before I started racing.
And the practice never ends. Every ride I make a number of mistakes. Things I didn't see as soon as I should have, lane positions that could have been better, not as smooth as possible on the controls...on and on. So I work on those things and try to be better.

Just want to be clear, Rich, that it's a privilege to be able to access your advice and I appreciate it and I do listen.

 

[RichDesmond]

...If for some reason you have add braking to avoid running wide simply get used to countersteering to keep your line.

YES!

If for some reason you have widen the corner due to obstacles or something unanticipated just release the brake to widen your line.

NO!

I said this above, but it's not a good idea to get used to using braking adjustments to change your line. It only works well if you have the happy coincidence of needing to lessen your braking and change your line together, by the exact amount that just the braking change will produce.
If you need to change your line mid-corner it's almost always because of something you didn't anticipate. Really rare for that to result in you wanting less brake.
Use counter steering and foot pressure to steer, use brakes to adjust speed. Be aware what changes in braking are going to do to your line, but don't use it as a primary steering input.

I'll get off my soapbox now.

 

[Sandy]

YES!
NO!

I said this above, but it's not a good idea to get used to using braking adjustments to change your line. It only works well if you have the happy coincidence of needing to lessen your braking and change your line together, by the exact amount that just the braking change will produce.
If you need to change your line mid-corner it's almost always because of something you didn't anticipate. Really rare for that to result in you wanting less brake.
Use counter steering and foot pressure to steer, use brakes to adjust speed. Be aware what changes in braking are going to do to your line, but don't use it as a primary steering input.

I'll get off my soapbox now.

Absolutely, just meant that it's good to know what the motorcycle will do given different situations. Not that you have to or want to depend it. As said, if you are depending on it you're going too fast for the street or not paying attention.

 

[Sam 78 GS750]

Wow! Lot of good info here. Thanks for taking the time to lay all this out, Rich. Not just helpful to Glib, the OP, but to a lot of folks here on the forums...like me.

 

[bwringer]

Building on what Rich and Bill have explained above... I'm going to wander away from the "trail braking" point a little.


Everyone is (hopefully) familiar with the concept of the "traction circle" or "traction pie". However you draw the diagram, the idea is that you only have a certain amount of traction at each tire at any given moment, and if you exceed that traction budget (the classic example is getting startled and adding braking to a high cornering load) you will become a passenger of physics.

In the same way, you only have so much mental "bandwidth" at any given moment; the human brain can only cope with a certain number of factors at once, and it can only process so fast.

So rewind a bit to the point when the OP's buddy got into a set of two corners too hot and exited the pavement on #2. Let's take a peek inside his brain at the moment he emerges from corner #1 and suddenly feels his entry speed for corner #2 is too high. You know, the "Oh <golly>!" moment.

Let's even assume corner #1 was perfect -- he emerged exactly where intended at the velocity intended, but he made a serious error in judgement back before entering corner #1 and has just now become aware of this. (Of course, if he popped out of #1 discombobulated in any way or "behind the bike", then it's even worse.)

At that moment, his mental bandwidth is pretty much full with sudden panic and various counterproductive "survival reactions" (see "A Twist of the Wrist 2" by Keith Code). Out of all the options available to him, he does not have the mental budget for a subtle, advanced technique like trail braking, nor can trail braking really provide much that's useful in an unfamiliar corner, like added traction or cornering clearance. Trail braking didn't have anything to do with the original error, and it won't fix this situation. And unless the rider is very well trained, any attempt to use the rear brake at this point is also VERY likely to become more like a panicked stab, leading to the classic, often-seen straight black line pointing to disturbed vegetation.

OK, so trail braking was totally beside the point. What was his best option?

Most likely, it was to simply ride around the damn corner. There's a saying in aviation -- "keep flying the airplane" -- many lives have been lost because pilots get so distracted by some problem that they neglected to keep driving the airplane. "Aviate, Navigate, Communicate". The same applies to motorcycling.

In a very, VERY high percentage of street crashes in corners, the bike could have made it, but the rider stopped riding. Perhaps the rider nailed the brakes, perhaps they got target fixated, perhaps they were leaning the wrong way (incredibly common; pavement hurts and your body's reaction is to shy away from it).

Lean farther, get your weight to the inside as much as possible. Get your ass off the seat and get low if you have the time. If you're not already dragging an elbow Marc Marquez style, there's ALWAYS more cornering clearance to be found. And in any case, if you do crash trying to ride around a corner, it'll be a lowside, not a straight on target-fixated splat or a headfirst highside dive into whatever's out there.

Another option. depending on when the problem became apparent and lane position, might have been to stand the bike up briefly and scrub off as much speed as possible in a few feet. You can do a LOT of braking in the moments when you're at or near upright in a transition between two corners. Of course, this isn't easy, but managing traction while braking is much more do-able in moments when you're not asking your tires and your brain to cope with a lot of cornering at that moment.


So anyway, back to trail braking. What's the proper time and place for trail braking? The answer is pretty much "the track".

It's a question of priorities. Trail braking is a technique for extracting the last few percent of cornering speed. It is not a magic potion that will allow you to scrub off speed mid-corner. It's pretty subtle stuff, and a lot of people are pretty damn fast without worrying about it.

In order to make cornering speed your highest priority, so that expending the mental bandwidth to use trail braking is worthwhile, you need a couple of things that don't exist on any public road. For example, nearly complete predictability of the surface, what or who is on that surface, etc. "Stuff" still happens on the track, of course, but generally you can have some trust that there's not going to be an oncoming Buick around the next corner.

You also need repeatability, and this is the real key. Even if you're already highly skilled with trail braking, to get much out of it you need a lot of repeatable practice in the exact same corners under predictable conditions. On the street, you simply don't have the luxury of repeatability, and that mental bandwidth can usually be used in many far more productive ways; instead of spending 5% or 10% of your brain worrying about trail braking, assign that processing power to "scan and predict".

That's not to say trail braking is completely useless on the street; it can be a way to make the bike behave a bit better in certain situations, and it can be a way to be a little smoother. One of the neat things about vintage bikes is how much they reward a little added smoothness. Even at relatively sane street speeds, the smoother you can be the fewer effects you'll feel from chassis flex and primitive suspension.

Long, heavy vintage bikes need the rear brake to stop quickly, so good smooth rear brake technique is essential in other ways than trail braking. Heck, it can even make things smoother and more enjoyable for a passenger so you get to ride more.

 

[glib]

More excellent advice. Turning into a great thread here.

I had a really great day riding with my son?his first real ride of any significant distance and lots of twists and elevation changes?so a handful for a brand new rider. We just took an easy pace and I told him I?d be practicing entering corners as I?d been advised (by Rich) looking for the apex in the blind turns and setting up properly for each subsequent corner and for him to follow as he felt comfortable.

We we met a group of riders for a burger but really rode on our own so with no one to try to keep up with I tried trail braking also and although it wasn?t much of a test at cruising speeds I was able to see how subtle pressure on the front brake can be done without risk of affecting lean.

Also, Rich, if you?re still reading, I changed my emulator springs down to the blue spring from the stiffer yellow, set them at 2.5 turns and the front was smooth as butter.

There are some great experiences to be had but sharing your favorite activity with your son or daughter is way up there.

 

[RichDesmond]

Brian, great post. Really like that you brought in the mental aspect, and only having so much mental bandwidth available. In the first Twist of the Wrist book Code refers to it as your "$10 worth of attention". That's your budget, so spend it wisely. That's one of the reasons why practice and constantly running scenarios constantly through your head while your riding are so important. The more automatic the right responses are the less mental capacity they require, freeing some up for other tasks.
It's also one of the big reasons I never use the rear brake while riding hard. It's one more thing to monitor and control, and I'm better off spending that attention budget elsewhere. I do know people who use it and benefit, but they're all a lot more talented than me.

 

[RichDesmond]

More excellent advice. Turning into a great thread here.

I had a really great day riding with my son—his first real ride of any significant distance and lots of twists and elevation changes—so a handful for a brand new rider. We just took an easy pace and I told him I’d be practicing entering corners as I’d been advised (by Rich) looking for the apex in the blind turns and setting up properly for each subsequent corner and for him to follow as he felt comfortable.

We we met a group of riders for a burger but really rode on our own so with no one to try to keep up with I tried trail braking also and although it wasn’t much of a test at cruising speeds I was able to see how subtle pressure on the front brake can be done without risk of affecting lean.

Also, Rich, if you’re still reading, I changed my emulator springs down to the blue spring from the stiffer yellow, set them at 2.5 turns and the front was smooth as butter.

There are some great experiences to be had but sharing your favorite activity with your son or daughter is way up there.

Sounds like a great day.

Glad the spring change on the emulator helped.

 

[GabrielGoes]

you want to start with the pads just barely starting to graze the rotors ever so slightly