Trail braking.

[klaviator]

I'm just curious.  Who understands what trail braking is and who here uses it?

[rjs987]

I know what it is but don't do it. I figure it is a band aid approach to coming into a sharp turn too fast. I learned long ago how to go into a turn at the right speed to avoid using any brake unless some obstacle was around the curve that wasn't expected. I prefer to use engine drag if possible. If I use any braking I try to get my bike as upright as possible and still stay safe.

I do know many ST1300 and BMW riders who do trail braking. And it is regularly done in motorcycle racing to get around curves faster. But those riders are REALLY skilled in braking technique.

[Stig / Major Tom]

My simple understanding is that it is cornering combined with braking at the same time.
Braking is decreased...then gone completely when nearing the apex, after which power is applied.
What bike was it that I first saw the electronics prevent the bike from trying to "right" itself  (stand up vertical) while braking in s corner......and leading to a runoff. KTM I think it was?

I have one tight steeply downhill turn which I approach cautiously in my frequent rainy dark rides after big winds.
Do my braking before I encounter the possible road debris ahead....never in the corner 🫣
Stig

[Alan F.]

My understanding was that trail braking is used to shift weight to the front suspension by braking as necessary before a turn, reducing the need to brake during the turn, but also the effect of the weight shift basically changes your suspension geometry by lowering front ride height by compressing your forks (just a little does it) decreasing the front suspension's amount of trail, which gives better handling and more front wheel grip through the turn.


Trail is the horizontal distance from where the front wheel touches the ground to where the steering axis intersects the ground.



Other ways of reducing trail are by using a larger diameter rear tire or a smaller diameter front tire, or by slipping fork tubes up a tiny bit in the triple clamp.


Lots of sport bikes in the 80s had a 16" front wheel and an 18" rear to reduce trail.

I cut throttle back at the last minute before a turn to accomplish this weight shift to the front end, usually this is enough to effectively reduce trail at low speeds. It's even enough on my motorcycles, I guess I don't ride that hard even if I'm pushing the speed limits, this is more of an open road or track technique that doesn't play well in traffic.

[Stig / Major Tom]

Stig

[klaviator]

I see there are a lot of misconceptions about trail braking out there.  That's not surprising considering that not that long ago a lot of "experts" were teaching that riders should get all their braking done before entering a curve.  Those "experts" included the MSF and Keith Code who wrote "A Twist of the Wrist" and founded the California Superbike School.  I thought it was crap when the MSF taught it when I took their courses back in the 80s and 90s.  I also took California Superbike School back in 91.  Common sense finally prevailed and neither the MSF or Keith Code teach that anymore.  There are a few MSF instructors out there who never got the word and still teach that outdated technique but they shouldn't be doing that.  Go to any advanced riding school and they will most likely be teaching trail braking. 

This video is over 13 minutes long but its worth watching and sets the stage for what I'll be posting later. 

[Neil955i]

Interesting vid Klav, thanks for posting.

[klaviator]

So what exactly is trail braking?

Trail braking is when a rider starts braking before entering a curve and continues braking into the curve.  Done correctly the rider will be decreasing brake pressure as he increases lean angle and will be off the brakes before the apex.  Normally trail braking is done with the front brake only, especially on the track and when done by sportbikes or other high performance bikes.

If the rider releases his brakes before entering the curve then it is NOT trail braking.

If the rider is already in the curve and applies his brakes, that is NOT trail braking.

Many riders, probably due to the BS the MSF used to teach, consider using the brakes while leaned over to be a dangerous technique that should only be used by experts.  This is simply not true and is a potentially dangerous attitude.  Trail braking as well as braking while in a curve are techniques that every rider who has gotten past the beginner stage should be able to do.  It's not rocket science but before attempting these techniques a rider should be comfortable with countersteering and riding curves as well as using his bikes brakes.  Understanding the dynamics of braking is important but far too many riders simply don't understand braking dynamics beyond which lever(s) to pull to slow their bike down.

It is also important to understand tire traction, not only for trailbraking but for riding in general. 

I'll cover all these topics in future posts.

[Neil955i]

A “bagger”? Never come across this nickname before, but it describes the hard case-equipped HDs well. Seeing racers hustling them around a race track is a hoot.

As an aside, are those machines modded for improved ground clearance?  I well recall the Electra Glide I rode around Colorado decked out at very modest lean angles!

[klaviator]

A “bagger”? Never come across this nickname before, but it describes the hard case-equipped HDs well. Seeing racers hustling them around a race track is a hoot.

As an aside, are those machines modded for improved ground clearance?  I well recall the Electra Glide I rode around Colorado decked out at very modest lean angles!

A Bagger Racing league was started a couple of years ago for racing between Harley and Indian Baggers.  These are race bikes with bags on them.  In real life a bagger refers so a cruiser type motorcycle with hard bags but not a tail trunk like an Electra Glide or Tour glide, at least that is my understanding.

As for limited ground clearance, this really varies a lot with stock Harleys.  Some start dragging as soon as you start leaning, others do pretty well.  A couple of years ago a couple of Harley baggers passed my on the dragon, the first time a Harley has ever passed me on a twisty road.  It's an interesting story:

I was taking a break at the overlook near the bottom of the dragon and getting ready to ride back up to Deal's Gap.  There was a Concours 14 also getting ready to go.  I wanted to let the Concours go first because I was on my Like 150i.  He was so slow getting ready to go I finally went first but I was expecting him to catch me.  After a few miles I did see some headlights behind me.  I also started hearing the distinct Potato.potato sound of a Harley.....Hmmm.  After a mile or so they caught up to my so I used a pull off to let them by.  It was two harley baggers followed by the Concours 14.  I pulled in behind them and tried keeping up.  Eventually the two baggers pulled away but I kept up with the Concours 14.  OK, I was on a 150cc scooter but I am still faster than most motorcycles on a twisty road.  These Harley riders knew how to ride and their bikes had decent cornering clearance.  It goes to show its more about the rider than the bike.

[klaviator]

Before going back to trail braking I'm going to discuss some real basics.  There is nothing more basic to riding a motorcycle or scooter than tire traction.  Without tire traction you couldn't accelerate, brake or turn.  Tire traction is a function of three things, Your tire, the road surface and the weight on the tire.  Tires varies from sticky race tires to very hard tires.  Once you go riding you are stuck with whatever tires you have on your scooter.  Road Surface.  This varies from clean dry pavement to wet to oily or gravel or debris covered.  You do have some control over this as you can choose to avoid patches of gravel or other slippery stuff.  Of high importance is recognizing stuff on the road that will affect traction.

Last is weight on the tire.  The more weight that is on a tire the more traction it will have.  The weight on your tires is not static.  It changes as you ride.  As you accelerate weight transfers from your front tire to your rear.  As you decelerate or brake the opposite happens.  This all sounds pretty simple right?  However, I don't think most riders really understand tire traction all that well.

Here's a video by Nich Ienatsch that hopefully explains things better than I do.

[Neil955i]

Your last sentence Klav? "It goes to show its more about the rider than the bike."

Absolutely. When riding in groups (I don’t anymore), I always felt any fool with a litre plus sportsbike could blast past me on the straight, but take me in the twisties? Then I’d be impressed.

These days I much prefer solo riding or with one other.  Safer and more enjoyable.

[klaviator]

I'm going to re post a diagram that stig posted because it is a good one.



The numbers in this diagram are just an example.  The actual used in trail braking can vary a lot.  This diagram shows a fairly aggressive street rider using trail braking.  How do I know that?  Two reasons.  A racer would be probably be braking harder than 70% approaching the curve.  A racer would not normally used a delayed apex line as shown.  A delayed apex is not the fastest way around the track but it is considered the safest line on the street.

So what exactly is happening in the diagram.

The rider is braking pretty hard approaching the curve.  Before starting to turn the riders lightens up on the brakes from 70% to 50%.  Then as he goes more into the curve he lightens up on the brake as he leans more until he is off the brake by the apex and then accelerates after passing the apex, increasing acceleration as he starts to straighten the bike up.  He used a delayed apex to stay outside and increase his sightline longer.  By the time he hit the apex he could probably see the corner exit before starting to accelerate.  If he was racing he would have apexed midway through that curve.

What is important, although the diagram doesn't show it,  is that the rider never exceeded 100% traction on his tires.  That is the the reason so many people are afraid to brake and lean at the same time.  They think they will lose traction and crash.  They think it takes an expert rider to balance braking and turning and not crash. 

It does take an expert to do it if you are trying to use close to 100% of your tires traction as a racer does.  However, on the street even experienced riders try to leave a margin for error.  In the diagram the rider was only using 50% of his traction when he started turning.  He had 50% left.  I'll bet the average street rider rarely uses more than 50% of his available traction when turning. 

Let's suppose instead of 50% braking the rider only used 20% when starting the curve and then tapered it off.  That's still trail braking and certainly not dangerous.  Like any technique, trail braking should be learned by starting real easy and then increasing the level you are doing it at. 

But why not just just doing all your braking before starting the curve?  What is the advantage of trail braking?

I'll discuss that next but first another video:

[klaviator]

What bike was it that I first saw the electronics prevent the bike from trying to "right" itself  (stand up vertical) while braking in s corner......and leading to a runoff. KTM I think it was?

I think it was KTM that first introduced cornering ABS.  It had absolutely nothing to do with a bike trying to stand up and running off in a corner.  Cornering ABS is designed to prevent your tires from loosing traction if you use your brakes to hard in a curve or you are braking in a curve and hit something slippery.  If you are leaned way over in a curve and grab a handful of brakes you will most likely crash.  Cornering ABS MIGHT prevent that from happening but it can't change the laws of physics.  It is still a good idea to use your brakes properly while in a curve even if you have cornering ABS.

But that is not what trail braking is all about.  Trail braking is already having your brakes on when entering the curve and smoothly decreasing the brake pressure.  Can you still loose traction even if trail braking correctly?  Sure you can if you hit something slippery.  It can also happen if you are just leaned over in the curve with no braking involved.  You still have to pay attention to the road surface as well as your speed. 

Even if you prefer the old technique of completing your braking before entering the curve, trail braking is a useful tool to have at your disposal if you need it.  I know there are some riders out there who will claim they have been riding for many years without trail braking and they don't need it and they aren't going to start now.  I have met some of those riders who have been riding forever and know it all.  They are safe because they ride slow and safely.  I'll bet the two Harley riders in the next video fell into that category:

[klaviator]

I know that some of you are still unconvinced.  You learned that brakes should only be used when upright because braking and leaning at the same time are dangerous.  Let's look as some scenarios.

Here is an example stig posted:

I have one tight steeply downhill turn which I approach cautiously in my frequent rainy dark rides after big winds.
Do my braking before I encounter the possible road debris ahead....never in the corner 🫣
Stig

For this scenario I think what stig posted makes sense.  Steep downhill, wet, debris.  Yeah, I'd go slow too.

Now lets change the situation a bit.  A steep downhill curve but it is a dry and sunny day.  So how steep is it?  I know some roads that are so steep and curvy that you will be braking in the curves whether you want to or not, especially on a scooter.  Scooters don't have nearly as much engine braking as motorcycles so if it is steep enough engine breaking won't be enough.  Another issue with scooters is that if you go too slow the clutch will disengage and now you have no engine braking.  If you live in Kansas or Florida you may never have ridden a road like this but they are out there.  I have ridden a bunch of super steep and curvy roads where you pretty much have to brake in the curves.  It makes more sense to trail brake than to wait until you feel uncomfortable with your speed and then have to apply your brakes mid turn.

Let's look at another scenario.  Downhill curve but not that steep.  Again, sunny and dry day.  So approaching the curve you brake to what you feel is a comfortable speed and then release your brakes before entering the curve.  After entering the curve you see a bunch of gravel all over the road.  The speed you thought was slow enough suddenly isn't.  So you don't believe in braking while leaned over.  Now what do you do?