Trail Braking?

[Twisties]

When I took rider training I was told:

 

1.  Trail braking is using the rear brake to stabilize the chassis from after turn entry until the apex.

2.  That it was for standard suspension bikes with nose dive on front braking, and unnecessary or even bad on a BMW with telelever front suspension that doesn't dive.  

 

Today I encountered a thread where riders are referring to using trail braking with the front brake.  They speak of entering the curve with some front brake and trailing off of it as they approach the apex.  I think this is still under the principle that entry speed is set before entering the curve, and this braking is about stability in the turn, not adjusting speed.  

 

This came up in the context of a rider saying he was using trail braking with the front brake before the apex, and then transitioning to rear brake on the exit.  

 

So now my mind is full of questions.

 

What is trail braking?  Do you do it?  How do you do it?  What bikes do you use it on (BMW Telelever or no)? Why do you do it and what does it do?

[chrisolson]

27 minutes ago, Twisties said:

Why do you do it and what does it do?

 

Helps me  trying to keep up with Whip in the corners 

 

My usage is mostly front brake as its easier to modulate although I do use both on initial deceleration if the entry speed is maybe a bit too great

 

And yes, for me,  its about speed, not stability.  Its continuing to apply a diminishing brake pressure into the apex rather than releasing most/all pressure at tip in.  This means you gain a few feet at a higher speed.  But the danger is to over do it and possibly tuck the front.  

 

As with a lot of riding techniques, individuals may apply their own unique style that suits them.

 

 

 

 

A fairly good link about trail braking  

 

 

 

[9Mary7]

Another......

 

[dduelin]

I understand and use trail braking up to the apex to manage available traction after tip-in . As apex approaches and lean angle increases less traction is available for braking so we bleed off brake. Depending on the speed and which motorcycle I am riding I use one or both brakes in concert.

[wbw6cos]

According to my extensive Trail Braking training at  the UnRally XX,  the process involves using the front brake going into a turn and then easing off and rolling on the throttle all in one smooth action.   The theory is to set the suspension up for the turn and not disrupt it as you exit.  Smooth in, smooth out.   It was great to feel it on the 125 cc Grom-clone bikes in a parking lot, but with the linked braking and Telever suspension, the reactions on my RT are slightly different.  

 

A good habit that came out of the class is the muscle memory.   Being prepared for braking into a curve sets you up for any surprises around the corner, which decreases reaction time.   

 

It turned out that I was already following the trail braking principles all along.  I did enjoy the training course and I am always open to learning better ways to ride and speed safely.

[dirtrider]

10 hours ago, Twisties said:

When I took rider training I was told:

 

1.  Trail braking is using the rear brake to stabilize the chassis from after turn entry until the apex.

2.  That it was for standard suspension bikes with nose dive on front braking, and unnecessary or even bad on a BMW with telelever front suspension that doesn't dive.  

 

Today I encountered a thread where riders are referring to using trail braking with the front brake.  They speak of entering the curve with some front brake and trailing off of it as they approach the apex.  I think this is still under the principle that entry speed is set before entering the curve, and this braking is about stability in the turn, not adjusting speed.  

 

This came up in the context of a rider saying he was using trail braking with the front brake before the apex, and then transitioning to rear brake on the exit.  

 

So now my mind is full of questions.

 

What is trail braking?  Do you do it?  How do you do it?  What bikes do you use it on (BMW Telelever or no)? Why do you do it and what does it do?

Morning  Jan

 

When someone says they are trail braking like this or like that then it somewhat depends on the brake system on the motorcycle they are riding & their line into & out of the curve or corner vs THEIR apex. 

 

A LOT of street motorcycle riders use an early apex, or use an incorrect apex for their entry line so use the brakes to get some added stabilization or to assist with turn-in. With the early apex riders they typically fight a line change (or couple of changes) mid corner as an early apex doesn't give them a smooth linear lean-in, or proper exit line. 

 

The type of braking system figures in on this also as with the (BMW) fully linked brake systems it is impossible to get just rear brake without some front brake added in. 

 

On the older partially linked (BMW) systems the front brake lever brings on both front & rear with the rear pedal just operating the rear without the front. On the older (BMW) partially linked you can ride in braking with both front & rear, then start  letting up on the front as you start your lean but there can be some instability if the rear braking pressure changes as the front linking to the rear lets up & the rear apply takes over. On these type systems some riders use more rear brake going into the curve (pre apex) so they don't get a rear brake pressure change when the front brake is released.    (kind of a learning thing on what feels the most stable)

 

On the later (BMW post EVO) partially linked systems there is still that possible rear brake pressure change mid corner as the rear brake is controlled by the end supplying the most pressure to the rear.  If you can get the correct rear brake pressure going in then you can get a smooth brake pressure transfer to the rear as you release the front brake.

 

Obviously the engine braking going into the curve or corner or  power apply coming out post apex can have a BIG effect on the braking & stability. 

 

There are other factors in play also as riding at easy speeds for a curve or corner you have plenty of reserve tire traction to brake about any way you like & not lock the front wheel up or slip wide. But a lot of riders that ride somewhat easy typically don't use the correct apex for the entry speed so need to make a few line changes mid corner then use braking apply changes to get a decent corner feel. 

 

On the BMW linked or partially linked systems if riding somewhat easy then I just use the front lever then let the braking computer figure the front/rear braking bias out  (it usually does a pretty good job without help). If riding faster or harder then I typically use enough rear brake apply entering so I can have a little more rear remaining as I let up on the front as I start my lean in then smoothly pick the power up.  I typically start picking the engine power up before full rear brake release so there is no free-roll mid apex.

 

I'm probably not the best to judge on this as I am a fairly aggressive rider that usually rides late apex so I brake very late & very hard (both front & rear brake)  while the motorcycle is still upright then smoothly pick the power up as I roll the apex. Even riding easy I tend to ride late apex with late braking so I can use more motorcycle lean through the apex & get a short smooth lean-in with smooth power pick up & a straight line out. 

 

 

 

 

 

 

 

 

 

[Twisties]

11 hours ago, 9Mary7 said:

Another......

 

Ok, so in this film, it is explained that prior to entry, when braking to establish entry speed, the nose has dived.  The purpose of trail braking is to keep the bike from suddenly rebounding as you release the brakes and enter the turn (stabilize suspension) and also make the bike more flickable (ease turn in on compressed front suspension).  This makes sense to me for non-telelever bikes, in a racing context.  On the street I'm seldom, if ever braking hard enough on entry to feel the rebound or upset the chassis as I release the brake.  But, at least it makes sense.

[Twisties]

11 hours ago, chrisolson said:

 

Helps me  trying to keep up with Whip in the corners 

 

My usage is mostly front brake as its easier to modulate although I do use both on initial deceleration if the entry speed is maybe a bit too great

 

And yes, for me,  its about speed, not stability.  Its continuing to apply a diminishing brake pressure into the apex rather than releasing most/all pressure at tip in.  This means you gain a few feet at a higher speed.  But the danger is to over do it and possibly tuck the front.  

 

As with a lot of riding techniques, individuals may apply their own unique style that suits them.

 

 

 

 

A fairly good link about trail braking  

 

 

 

 

Good link, thanks!  A somewhat broader explanation than in 9Mary7's video, and more oriented to street riding.

[Twisties]

2 hours ago, dirtrider said:

Morning  Jan

 

When someone says they are trail braking like this or like that then it somewhat depends on the brake system on the motorcycle they are riding & their line into & out of the curve or corner vs THEIR apex. 

 

A LOT of street motorcycle riders use an early apex, or use an incorrect apex for their entry line so use the brakes to get some added stabilization or to assist with turn-in. With the early apex riders they typically fight a line change (or couple of changes) mid corner as an early apex doesn't give them a smooth linear lean-in, or proper exit line. 

 

The type of braking system figures in on this also as with the (BMW) fully linked brake systems it is impossible to get just rear brake without some front brake added in. 

 

On the older partially linked (BMW) systems the front brake lever brings on both front & rear with the rear pedal just operating the rear without the front. On the older (BMW) partially linked you can ride in braking with both front & rear, then start  letting up on the front as you start your lean but there can be some instability if the rear braking pressure changes as the front linking to the rear lets up & the rear apply takes over. On these type systems some riders use more rear brake going into the curve (pre apex) so they don't get a rear brake pressure change when the front brake is released.    (kind of a learning thing on what feels the most stable)

 

On the later (BMW post EVO) partially linked systems there is still that possible rear brake pressure change mid corner as the rear brake is controlled by the end supplying the most pressure to the rear.  If you can get the correct rear brake pressure going in then you can get a smooth brake pressure transfer to the rear as you release the front brake.

 

Obviously the engine braking going into the curve or corner or  power apply coming out post apex can have a BIG effect on the braking & stability. 

 

There are other factors in play also as riding at easy speeds for a curve or corner you have plenty of reserve tire traction to brake about any way you like & not lock the front wheel up or slip wide. But a lot of riders that ride somewhat easy typically don't use the correct apex for the entry speed so need to make a few line changes mid corner then use braking apply changes to get a decent corner feel. 

 

On the BMW linked or partially linked systems if riding somewhat easy then I just use the front lever then let the braking computer figure the front/rear braking bias out  (it usually does a pretty good job without help). If riding faster or harder then I typically use enough rear brake apply entering so I can have a little more rear remaining as I let up on the front as I start my lean in then smoothly pick the power up.  I typically start picking the engine power up before full rear brake release so there is no free-roll mid apex.

 

I'm probably not the best to judge on this as I am a fairly aggressive rider that usually rides late apex so I brake very late & very hard (both front & rear brake)  while the motorcycle is still upright then smoothly pick the power up as I roll the apex. Even riding easy I tend to ride late apex with late braking so I can use more motorcycle lean through the apex & get a short smooth lean-in with smooth power pick up & a straight line out. 

 

 

 

 

 

 

 

 

 

 

Thanks for bringing up linked brakes.  I had meant to do that in the OP, above, and forgot.  On my hexhead RT it's the system where the front lever actuates both front and rear brakes, but the rear brake actuates only the rear brake.... so you can either add rear braking pressure to the mix or use the rear independently.  Very useful in some situations, like on dirt where rear braking may be called for.  This is the system you call partially linked.

 

I had assumed it was the same on my 2020 (and Sharon's 2021) GS.  Now, I don't know which system the GS's have.   Fully linked or partially linked post-EVO (and what is EVO?)?  

 

My riding style is mostly late apex. 

 

 

[Twisties]

Ok, so to summarize, then:  Trail braking is about easing the transition from the major pre-turn-in braking to the apex and it's purposes are to keep the suspension more stable (prevent rebound as you come off braking) and improve turn in ease.  Also, to allow an increased entry speed, allow for more speed adjustment in the turn, and more ability to react.  It is about balancing the available traction, most in straight line braking, and reducing as lean angle increases towards the apex... hence trailing braking pressure as you approach the apex.  

 

Ok, I probably don't have it all, but I've learned a lot.  Thanks!

[dirtrider]

55 minutes ago, Twisties said:

 

Thanks for bringing up linked brakes.  I had meant to do that in the OP, above, and forgot.  On my hexhead RT it's the system where the front lever actuates both front and rear brakes, but the rear brake actuates only the rear brake.... so you can either add rear braking pressure to the mix or use the rear independently.  Very useful in some situations, like on dirt where rear braking may be called for.  This is the system you call partially linked.

 

I had assumed it was the same on my 2020 (and Sharon's 2021) GS.  Now, I don't know which system the GS's have.   Fully linked or partially linked post-EVO (and what is EVO?)?  

 

My riding style is mostly late apex. 

 

 

Morning Jan 

 

"so you can either add rear braking pressure to the mix or use the rear independently."  --- This doesn't work quite like most riders think. 

 

The rear brake on the later I-ABS gen-II 1200 RT (hexhead) is not an addition type system. It is basally an either/or system. 

 

Seeing as the rear brake is a single input caliper (only one pressure line going in) it can only have one braking input at a time. 

 

So it can EITHER be controlled by the front brake linking (using the rear servo pump) OR controlled by the rear brake pedal (direct rear master cylinder control). It can't have both controlling at the same time.

 

There is a valve in the rear brake circuit that controls the rear brake input by selecting what end supplies the highest pressure at that time. 

[Twisties]

2 minutes ago, dirtrider said:

Morning Jan 

 

"so you can either add rear braking pressure to the mix or use the rear independently."  --- This doesn't work quite like most riders think. 

 

There rear brake on the 1200 RT (hexhead) is not an addition type system. It is basally an either/or system. 

 

Seeing as the rear brake is a single input caliper (only one pressure line going in) it can only have one braking input at a time. 

 

So it can EITHER be controlled by the front brake linking (using the rear servo pump) OR controlled by the rear brake pedal (direct rear master cylinder control). It can't have both controlling at the same time.

 

There is a valve in the rear brake circuit that controls the rear brake input by selecting what end supplies the highest pressure at that time. 

Oh, wow!

 

So, what system is on the newer bikes, the current model GS's?

[dirtrider]

44 minutes ago, Twisties said:

Oh, wow!

 

So, what system is on the newer bikes, the current model GS's?

Morning Jan

 

I can't say for sure as I haven't dissected the latest ABS brake controller yet but my best guess is that it operates the same way as it still has a single rear caliper input & a single rear servo pump. 

 

With just a single input rear caliper it can only use one input at a time so it would almost have to still be an either/or rear system. 

 

If it didn't use a selector valve to use one or the other inputs individually, and  hydraulics being what they are, if both front linking & rear input were not specifically isolated & separated then the front linked servo side would blow brake fluid out of the rear brake fluid reservoir every time the front linking applied the rear brake.  (pretty simple hydraulic fundamentals)

 

The thing is, you can still use the rear braking to your advantage if used with knowledge of operation & good riding feel. 

 

If you can find the point that the rear brake pedal takes control of the rear brake over the front linking then it will retain that rear brake control even after the front linking pressure drops as front brake is released.

 

Of it you can get the rear brake input pressure close to the front input then it will simply drop the rear brake pressure to what the rear is currently supplying as you release front pressure. (not a big step down as the front is released).

 

The biggest problem is with those riders that try to add just a little extra pressure on the rear brake pedal as then the rear braking force will drop off suddenly to that lower rear braking pressure as the front is released.  

 

Now if the rear brake pedal is supplying slightly more rear barking pressure than the front linking is supplying then there is no change in rear braking pressure or braking force when the front linking pressure is released as the linked pressure wasn't doing anything on the rear anyhow. 

 

Just to clarify: once the system goes into an ABS event then the ABS controller shuts the rear brake foot pedal input off & takes full control of the rear braking until the ABS event is over (traction is restored)  or braking is released. 

 

 

[Twisties]

Thanks DR!

[dduelin]

3 hours ago, dirtrider said:

Morning  Jan

 

When someone says they are trail braking like this or like that then it somewhat depends on the brake system on the motorcycle they are riding & their line into & out of the curve or corner vs THEIR apex. 

 

A LOT of street motorcycle riders use an early apex, or use an incorrect apex for their entry line so use the brakes to get some added stabilization or to assist with turn-in. With the early apex riders they typically fight a line change (or couple of changes) mid corner as an early apex doesn't give them a smooth linear lean-in, or proper exit line. 

 

The type of braking system figures in on this also as with the (BMW) fully linked brake systems it is impossible to get just rear brake without some front brake added in. 

 

On the older partially linked (BMW) systems the front brake lever brings on both front & rear with the rear pedal just operating the rear without the front. On the older (BMW) partially linked you can ride in braking with both front & rear, then start  letting up on the front as you start your lean but there can be some instability if the rear braking pressure changes as the front linking to the rear lets up & the rear apply takes over. On these type systems some riders use more rear brake going into the curve (pre apex) so they don't get a rear brake pressure change when the front brake is released.    (kind of a learning thing on what feels the most stable)

 

On the later (BMW post EVO) partially linked systems there is still that possible rear brake pressure change mid corner as the rear brake is controlled by the end supplying the most pressure to the rear.  If you can get the correct rear brake pressure going in then you can get a smooth brake pressure transfer to the rear as you release the front brake.

 

Obviously the engine braking going into the curve or corner or  power apply coming out post apex can have a BIG effect on the braking & stability. 

 

There are other factors in play also as riding at easy speeds for a curve or corner you have plenty of reserve tire traction to brake about any way you like & not lock the front wheel up or slip wide. But a lot of riders that ride somewhat easy typically don't use the correct apex for the entry speed so need to make a few line changes mid corner then use braking apply changes to get a decent corner feel. 

 

On the BMW linked or partially linked systems if riding somewhat easy then I just use the front lever then let the braking computer figure the front/rear braking bias out  (it usually does a pretty good job without help). If riding faster or harder then I typically use enough rear brake apply entering so I can have a little more rear remaining as I let up on the front as I start my lean in then smoothly pick the power up.  I typically start picking the engine power up before full rear brake release so there is no free-roll mid apex.

 

I'm probably not the best to judge on this as I am a fairly aggressive rider that usually rides late apex so I brake very late & very hard (both front & rear brake)  while the motorcycle is still upright then smoothly pick the power up as I roll the apex. Even riding easy I tend to ride late apex with late braking so I can use more motorcycle lean through the apex & get a short smooth lean-in with smooth power pick up & a straight line out. 

 

3 hours ago, dirtrider said:

I guess there may be reasons for an early apex but for street riding on two wheels I can't think of a reason to ever choose an early apex. Am I missing something?

 

 

 

 

 

 

 

 

 

[dirtrider]

28 minutes ago, dduelin said:

I guess there may be reasons for an early apex but for street riding on two wheels I can't think of a reason to ever choose an early apex. Am I missing something?

Afternoon dduelin

 

Then you need to patriciate in more group rides. Don't lead them, stay back in the rear & watch & observe. 

 

I think (my take anyhow) is that fear of riding into the curve or corner too far is the biggest driver of early turn-in then early apex. 

 

Another thing I have observed is slowing down too much before the curve so the entry speed is too darn slow to get a single correct apex. I see some riders that change their line through a curve 2 or even 3 times trying to get some sort of an exit line. 

 

Or, I have seen riders that are going way too slow through a curve but are still trying to kiss the inside mirror so then they have to try to make (force) the motorcycle do something that it naturally doesn't want to do. I have followed riders that are leaning way-in in curves that I have to actually use cross control to get my motorcycle to stay on it's natural line at the same speed. 

 

If a rider starts their turn-in too early, or on an incorrect entry-line for their speed, then hitting a correct apex is about impossible. 

[Hosstage]

Your comment to ride in back and observe other riders is right on, it is always interesting to watch the many techniques used. Some I can't handle watching anymore and must pass to get out in front and run my lines without being held up and making mental mistakes watching them screw up corners one after another.

[dduelin]

I guess I asked the question looking for a purposeful good reason to set up an early apex. I believe that on the street one can never go wrong choosing a late apex. It opens sight lines and leaves line options for surprises that might reveal themselves late in the turn. I learned that early and it is always reinforced in skill training books and range riding courses like Lee Parks Total Control and the high performance sport touring track day school my local MOA chapter used to put on. You extend sight lines, leave options open and lean the bike the most the least amount of time.

 

I learned a lot about smooth braking and throttle control with an R100 I owned 2006 - 2012. The combination of long travel softly sprung underdamped forks and shaft jacking inherent in the mono lever rear swing arm made throttle control and braking late into a turn very interesting if I got it wrong. Clumsy on and off the brakes and gas and it would bob and pitch like a hobby horse and heaven forbid if I had to chop the throttle after committing to a line. But if I got it right it was very rewarding. BMW's Telelever and Paralever are very forgiving in this regard.

[MikeB60]

2 hours ago, Twisties said:

Oh, wow!

 

So, what system is on the newer bikes, the current model GS's?

The latest BMW models have ABS Pro (Cornering ABS) or in the case of the RR, Race ABS. ABS Pro is a linked system that provides ABS function while cornering. This function is separate from trail braking more of a panic stop aid.

 

Search MotoJitsu and CanyonChasers on YouTube for some decent explanations of trail braking and why it's beneficial to learn and practice the techniques. 

[chrisolson]

1 hour ago, dduelin said:

I guess I asked the question looking for a purposeful good reason to set up an early apex.

 

I'll offer ...blind right hand turns on mountain roads.  An early apex and continuing to hug the inner line is a defense against an approaching vehicle suddenly appearing on or over the line into your lane ...   it has happened 

 

Conversely, on blind left hand turns a later apex does give a better sight line and extra time / room if needed to stay away from any wayward vehicle.

[dduelin]

17 minutes ago, chrisolson said:

 

I'll offer ...blind right hand turns on mountain roads.  An early apex and continuing to hug the inner line is a defense against an approaching vehicle suddenly appearing on or over the line into your lane ...   it has happened 

 

Conversely, on blind left hand turns a later apex does give a better sight line and extra time / room if needed to stay away from any wayward vehicle.

I agree that is a good practice on blind right turns but by definition an apex is the closest point of the line to the inside of the corner. We clip apexes not hug them for some distance. Hugging the inside of the turn is describing an arc with the radius being the roughly the same as the inside edge of the road. There isn't an apex in this circumstance but I see your point. On my first trip to the mountains my mentor told me to mentally reduce the lane width by half and imagine the lane 6 or 7 feet wide instead of the actual 12 or 14 feet. He admonished me to stay 3 or 4 feet away from the center line at all times if I could not see all the way through the corner due to terrain or foliage. In a blind right hand corner it is still safer to plan a late apex but do not use the outside half of the lane. You'll see further into the turn before committing and still have a large margin of lane outside of your line to account for center line crossers.

[gmcjetpilot]

Unless you are riding hard and fast like a raped ape treating the street like a race track (dumb in my opinion go to track to play Valentino Rossi) you don't need this brake technique. There are other techniques. 

 

To go fast you race, accelerate as hard as you can between turns, brake hard late as you can,  release brakes at some point before or as you enter turn, accelerate out of turn... no brake on exit of course. So how and when you release brakes to slow for turn is tye question? Depends.

 

First if speed in straight before turn  is at or bellow a speed you can take the turn then no brake. If you are going as fast as you can in straight at speed we'll above speed you can safely do turn, then brake... a lot.

 

in theory you enter a turn slow enough you don't crash. Can you keep slowing after you lean in? Yes. You can leave some brake on. Front brake is normally what you use for trail (off) braking. You start first part of turn with front brake and slowly release (or trail off) as needed as yiu roll on throttle. What does it do for you?

 

 It compresses front forks and changes rake/trail of bike making it easier to turn in (in theory). Yes it works on BMW with leaver. They still have forks. You still changed geometry. In theory it makes turn in easier, in theory. Again all this is going fast, braking hard, accelerating hard. Cruising no or little braking is needed entertaining turn.

 

BTW "in theory" means on paper it is true but how practical or effective in real world varies. Some go fast riders it may help. Average riders not riding fast will get less benefit, some, just less. In other words fo you need this technique. May be not. It takes more effort.

 

It also changes the weight distribution, putting more on front, increasing tire contact patch area.

 

I will check speed before turning in, with roll off (engune braking) and/or brake. However I normally release brakes before leaning in, no brake and neutral or slight acceleration.

 

Normally if riding at speeds that aren't insane, turn exit viable, known turn,  I may not slow down or brake. In other words constant speed, no brakes.

 

Trail ( off ) braking is not something you need all the time. Some riders never need this. However the take away is you can brake in a turn and may need to do it for many reasons. So riders should explore braking in the turn (carefully). You can brake any time. Normally most don't need or want to brake leaning over, but you can.

 

I do trail braking sometimes. If I brake hard before a turn and release all brake the front suspension extends abruptly. That is OK if the bike has time to get stable and settled before turning in.

 

However trail brake is about a technique to brake late and into start of turn, go faster (well above posted speed limit). If you are a good rider I doubt it will make you faster on a group ride. Track day? Yep shave a second off laps, may be.

 

All this is in theory and pushing limits. If you are cruising no brake or rolling off throttle, or checking speed with brakes and releasing fully before turn, it will work fine...  BEFORE you practice check your brake pads.