Who uses the rear brake pedal?

[Bendy toy]

I've found on a Telelever suspended bike, it's possible to brake right up to the apex, if necessary, using the front brake.

I almost always use the front brake and when pressing on will brake right up to the bend apex, then off the brake and onto power. the bike will do this on any ESA setting. I could not even think about doing that on a normal fork bike. The forks have to settle before going on the power or you'll cause the front end to wash out. On gravel, I'm more careful and moving more slowly (obviously) but again it's front brake. The back has minimal slowing effect and does nothing useful to stabilise the bike. The Telelever has no need to be stabilised so I don't bother.

Telelever is good but Hossack gave the same handling effect with less weight and less cost. Road handling would be even better if the back end did not dip/squat under power. Presumably BMW programmed the rear end squat to improve offroad ability.

 

[RedRick Esq.]

Trail braking to keep the power on and pulling but settling the bike when in too hot

 

[robb]

Hoggle Choggle

That must affect your fuel consumption....

 

[Bendy toy]

I don't get this "rear brakes steady the bike before a bend" thing. If you need more steering then counter steer it down. If going too fast you need to lose speed. Only the front brake will do that in the time/space available.

I did a load of Alpine passes few years ago. The rear brake was handy to hold the bike on hills (front brake just got dragged down). Beemer is the same in Devon where we have some very steep back lanes. Riding downhill the rear was/is all but useless. I did the Alps an Aprilia Pegaso 650 with nothing special front forks. Rear tyres had virtually no chicken strips and fronts wore the shoulders long before the centreline so must have been making proper use of the roads.

 

[Reggie P]

Yep I still use my rear pedal too for the final halt which helps prevent diving.

I take it you have a non-telelever bike? I don't experience dive on the GS, imho its the bikes best feature.

 

[Reggie P]

Trail braking to keep the power on and pulling but settling the bike when in too hot

You are not alone in doing this. But power against brakes ?

What's the point ?


PS are the guys who use the rear brake against open throttles, the same guys who complain the rear pads only last 3'000 miles ? Curious !

 

[GS TRV]

I don't get this "rear brakes steady the bike before a bend" thing. If you need more steering then counter steer it down. If going too fast you need to lose speed. )

What if you haven't reached the turn yet?

 

[AlexG]

I don't get this "rear brakes steady the bike before a bend" thing.

It is generally used when in a bend rather than before the bend.

As I understand it the main reasons it is recommended are two-fold:

• Using the back brake minimises the weight transfer to the front wheel/tyre, which should help to reduce the risk of the front tyre exceeding its grip level and washing out.
• Applying the front brake will cause a change to the steering input*, which effectively makes the bike stand/straighten up. In theory a corresponding opposite steering input at the bars will counteract this, though I am not convinced it is a practical option.

*When cornering the tyre contact patch is off to the side of the wheel's centre line which means there will be an off-centre force, whereas when upright it is aligned with the the centre line of the wheel, which is why when upright there will be no steering input (irrespective of single or twin disc setup).

A deceleration from the rear brake will transmit the forces to the front wheel through the centreline of the forks and as such there is no direct steering input in the same way.

Or at least I think that is how the science works!

 

[Reggie P]

[*]Using the back brake minimises the weight transfer to the front wheel/tyre,

Sorry , no disrespect Alex, but thats "bollox."
The weight xfer to the front wheel is a result of deceleration. Nothing to do with which brake is used.

 

[Bendy toy]

As I understand it the main reasons it is recommended are two-fold:

• Using the back brake minimises the weight transfer to the front wheel/tyre, which should help to reduce the risk of the front tyre exceeding its grip level and washing out.
  Only because the R1200GS rear brakes is too weedy to slow the bike enough to have any useful decelerative effect
• Applying the front brake will cause a change to the steering input*, which effectively makes the bike stand/straighten up. In theory a corresponding opposite steering input at the bars will counteract this, though I am not convinced it is a practical option.
  That applies on a bike with normal forks because about 10% of the braking effort goes into compressing the front springs. It has minimal compressive effect on a Saxon (sorry) Telelever fork.
  

*When cornering the tyre contact patch is off to the side of the wheel's centre line which means there will be an off-centre force, whereas when upright it is aligned with the the centre line of the wheel, which is why when upright there will be no steering input (irrespective of single or twin disc setup).
Try powering out of a bend on a big normal folks bike and it will pick itself up. On a Saxon fork the power and brakes don't affect the steering so rider has to consciously counter-steer the bike out of the bend.
Tyre contact patch is always under the bike centre of gravity so it makes no steering difference whether front or rear brake is used.
The only effect is tyre loading always an issue near the limit

A deceleration from the rear brake will transmit the forces to the front wheel through the centreline of the forks and as such there is no direct steering input in the same way. . Its all about tyre contact patch See previous comment

Or at least I think that is how the science works!

 

[Bendy toy]

if anyone is sufficiently interested to know why bikes handle as they do. I have a mechanical engineer's lecture transcript from Damian Harty a vehicle handling expert.

 

[Bendy toy]

It is generally used when in a bend rather than before the bend.

As I understand it the main reasons it is recommended are two-fold:

• Using the back brake minimises the weight transfer to the front wheel/tyre, which should help to reduce the risk of the front tyre exceeding its grip level and washing out.
• Applying the front brake will cause a change to the steering input*, which effectively makes the bike stand/straighten up. In theory a corresponding opposite steering input at the bars will counteract this, though I am not convinced it is a practical option.

*When cornering the tyre contact patch is off to the side of the wheel's centre line which means there will be an off-centre force, whereas when upright it is aligned with the the centre line of the wheel, which is why when upright there will be no steering input (irrespective of single or twin disc setup).

A deceleration from the rear brake will transmit the forces to the front wheel through the centreline of the forks and as such there is no direct steering input in the same way.

Or at least I think that is how the science works!

This confuses the effects of braking and power on a bike with normal forks. It also does not explain why a normal forks bike will straighten up when you hit the brakes mid bend but also when you hit the power. It doesn't happen the same (or at least to the same extent) on a bike with Saxon or Hossack fork.

 

[The bigun]

I hardly ever use my rear brake because it will kick in the ABS with not a lot of pedal pressure.

I

That doesn't sound like a too weedy brake on a Gs

 

[robb]

I hardly ever use my rear brake because it will kick in the ABS with not a lot of pedal pressure.

I already get a high wear rate on pads and disc so the back is clearly getting a lot of use from the linked brake system. So apart from total panic stops (where another few % could save the day) the rear brake pedal is all but redundant.

Just because you haven't developed the skill to use the rear brake without causing the ABS to activate doesn't make the brake redundant. Give this a go you may find it useful https://www.lincolnshire.gov.uk/lin.../motorcycling/performance-plus/120336.article

 

[Captain Black]

Apart from slow stuff / setting off on slopes/ slow stops etc etc.
The back brake is there to be used, its about percentages , I'm about 80% on the front 20% on the rear variable on conditions etc etc.

 

[AlexG]

Sorry , no disrespect Alex, but thats "bollox."
The weight xfer to the front wheel is a result of deceleration. Nothing to do with which brake is used.

OK it's 'bollox' I agree...poor terminology on my behalf, there is no weight transfer - other than a small shift due to movement of fluids the weight distribution of a bike is fixed.

The change in loading is a result of the forces generated by applying the brakes...

Given that bikes are not symmetrical and generally speaking have different suspension systems front and rear, these forces will have a different effect (magnitude/direction) depending on where they are applied to the chassis (i.e. whether application of front or rear brake)...is there a flaw in this basic reasoning?

 

[Zorro]

Thanks. Test done... Yes, engine off, pull front brake and wheel still rotates. Does this confirm modulator? Big job? Cheers
Just in case, engine off, back brake on, the wheel does not rotate...

Is it the modulator that activates the rear brake when the bike is running because on the centre stand engine off and pull the front brake lever the rear wheel still rotates freely?
2008 R1200GS with ABS.

 

[Reggie P]

For anyone who wants to understand more about braking.... Keith Code is good value .

See here ; http://www.motomom.ca/keith-code-on-trail-braking-exclusive-interview/

 

[AlexG]

if anyone is sufficiently interested to know why bikes handle as they do. I have a mechanical engineer's lecture transcript from Damian Harty a vehicle handling expert.

I'll take you up on that, I am interested to see what it says...I'll PM you shortly.

With respect to the tyre contact patch and braking forces...I am not referring to diving or extending (so it is largely irrelevant what type of front suspension is used) it is to do with the fact that there is an equal and opposite reaction from the road surface through the tyre and into the chassis.

The practical effect of this reactive force is that the bike feels like it is trying to stand up when what is actually happening is that the angle of the reactive force (though the off centre contact patch) is such that as well as slowing the rotation of the wheel it is also imparting a twisting force which causes the bike to feel like it wants to stand-up...release the brakes and the equal and opposite reaction goes way and the bike will easily drop back into the corner.

If I was any good with CAD I'd do some diagrams, but I am not so I won't.

 

[tanneman]

Using the rear brake. The reason why #93MM doesn't crash going quicker than any other Honda rider in MotoGP.