BMW R1200RT/R1250RT Forum

Hi all


As this bike is new to me, still learning.  I find the rear braking odd, am I right in thinking the front brake when applied, applies the rear brake also?  So why have a rear brake pedal? 


Also, if they are linked, does applying the rear brake affect the front brake?


General braking at very slow speeds I use the rear, helps control the bike obviously.  But normal 30mph plus when braking, I use front with rear applied quickly after. 


But I feel the rear brake pedal moving as if I didn’t need to press it???


Anywhere I can read up on this or can you guys help me out.  Thx

I believe the 2010 RT has I-ABS Gen 2 and so  has linked brakes from the front lever only.

If you only apply the front brake lever, you are mainly controlling the front brake pressure, then the ABS computer is applying the rear  brake using an electric  servo pump. The computer is designed to monitor front braking pressure as well as wheel deceleration, and then match the rear braking to give you even front to rear braking....if that makes sense!

If you step on only the rear pedal then you only get rear braking, with no servo.

If you use the rear pedal while using the front brake lever, the front still controls the rear brake through a servo, but as soon as you apply more pressure to the rear pedal than the front is supplying, a valve closes and you take control of the rear brake using the brake pedal.

If you ease off the rear pedal while still using the front lever, as soon as the rear pedal pressure drops below the front pressure it reverts back to front control of the rear brake - whichever end  is supplying the most rear brake pressure has control over the rear braking.

Of course, the ABS system overrides both ends if the computer senses impending wheel lock-up or excessive rear wheel lift.

I think! 


Pete

Found this on another forum, a similar question was asked about a 2008 1200RT.  Much the same as milleplod described.






"BMW's Integral ABS (Anti-Lock Braking System)
BMW Motorrad’s new Integral ABS technology has been developed separately from the previous system and the entire layout of the system has been newly conceived from the ground up.

Capitalizing on progress in technology in both hydraulics and electronics, the development engineers have succeeded in simplifying the architecture of the system while at the same time enhancing its functions to an even higher standard. The result is supreme stopping power and very short stopping distances even without electrical power assistance on the brakes.

BMW Motorrad’s new Integral ABS is no longer based on the plunger principle or, respectively, the ram pressure process used on previous generations, but instead is conceived as a valve system. Carried over from automotive applications, this control concept is now able to ensure a very high standard of all-round comfort and convenience in every respect.

In particular, feedback of brake pressure modulation on the brake lever has been reduced by recent development of the control valves and management to such an extent that it no longer has any kind of adverse effect, thus paving the way for introduction of the new system also in the topmost segment of BMW motorcycles.

The new Integral ABS system applies brake pressure on the front wheel brake solely by means of a hydraulic circuit, thus acting entirely in response to the operating forces applied on the hand lever. This, in turn, ensures a more direct feeling of the brakes particularly important to the sports-minded rider. And now the rider no longer has to get used to any change in control or operation of the brakes when switching over from a motorcycle without ABS.

The new system naturally maintains the proven semi-integral function, that is automatic activation of the rear-wheel brake when operating the front wheel brake. Pressing the foot brake alone, however, the rider, as in the case of a conventional system, activates only the wheel brake at the rear.

As with the previous system, the advantages of this integral brake are ideal brake force distribution on both wheels under all conditions, naturally taking load conditions into account, as well as enhanced control enabling the rider to detect at an early point the risk of the rear wheel lifting off when applying the brakes all-out, and to take appropriate counter-action.

To provide the desired integral function, brake pressure for the rear-wheel circuit is generated and built up by an electronically controlled hydraulic pump. This offers the advantage of pressure management and control completely independent of the front wheel circuit – which is the prerequisite for dynamic, adaptive and, ultimately, consistently ideal brake force distribution to the rear wheel as well as fully independent brake management and control.

In the event of any deficiencies in the hydraulic pump or electrical components, the rear-wheel brake acts hydraulically as with a conventional system, overriding the integral function. This has no effect on the proper operation of the front-wheel brake, the only difference being that the ABS function is no longer operative in the event of such a deficiency."

And we wonder why it's expensive to fix when it goes wrong! 

Pete

Thanks very much. You guys are the best.  I suppose I’m more clued up now on it. 


So basically I don’t really need to apply the rear foot brake at all as the computer will detect front brake application and servo applies pressure to rear, correct?


Anything else different with these bikes to “ normal “ techniques?


Gears don’t changed down on their own too do they lol


Yes, I can see why abs could cost lots, fingers crossed my 17000 miles 2010 will be ok for another 17000 lol.


 

I very, very rarely use my rear brake via the pedal, I never have done on whatever bike I've had. On the RT, as you say, the bike will apply it for you - I'd say don't overthink it, stick with the lever only. Being a big twin engine, an awful lot of deceleration can be done with engine braking anyway. If you're in the habit of misreading bends though, you might want to use the rear a bit......  ;D

Pete

Wouldn't a 2010 be non-servo ?  My 2007 is non-servo and linked as millipod said.

Rod wrote: Wouldn't a 2010 be non-servo ?  My 2007 is non-servo and linked as millipod said.

I believe it would be 'non servo' in the sense that it doesn't have the full-servo system that the earlier bikes had - my '06 has servo brakes that become particularly ineffective should the servo fail.....ie they're virtually non-existent without it!  :wonder:


I think it's the terminology that's slightly confusing. iABS 2 has an electrically-controlled pump to provide rear brake pressure, so, in that sense, it's 'assisted' - 'servo' is a bit of a misnomer really.
Pete

milleplod wrote: <snip> iABS 2 has an electrically-controlled pump to provide rear brake pressure, so, in that sense, it's 'assisted' - 'servo' is a bit of a misnomer really.
Pete

We'll that's the new thing I learnt today, I had incorrectly assumed it just split the pressure from the front master cylinder.

Rod wrote: Wouldn't a 2010 be non-servo ?&nbsp; My 2007 is non-servo and linked as millipod said.

It would indeed be non servo, but it would have ABS, which is the thing you loose when you perform a Servoectomy on servo equipped bikes.

Rod wrote:
We'll that's the new thing I learnt today, I had incorrectly assumed it just split the pressure from the front master cylinder.

I gleaned that info from BMW's own blurb on the then-new iABS2 system - RealOEM describes what I'd call 'the ABS unit' as a 'pressure modulator', so presumably there's some electrickery in it that boosts rear pressure when needed.

Interestingly, I was considering having my full-servo setup removed when I first got the bike earlier this year, rather than waiting for it to fail. I spoke to Steve at Rainbow Workshop (ex-Rainbow BMW mechanic) about it, then did a bit of research with the old Southport Superbikes dealer (now Bowker) who supplied and serviced it from new - glad I did, they told me it had had a new modulator fitted only 2 years ago! It was supplied and fitted under the BMW Insured Warranty, so there was no invoice for it with the bike when I bought it - well over £2k! Bowker very kindly eMailed me a copy invoice to put in the history folder. Steve's hopefully going to do a fluid flush and change soon - looking in both reservoirs, the fluid's still crystal clear, a good sign that all's well internally, apparently....so, I'll keep the system a bit longer! It's very powerful - one-finger braking, fully laden - but I find it quite snatchy at low speeds and don't seem to be able to recalibrate my brain to suit!&nbsp; :alas:


Pete

Why change something that isn’t broke and works I say.&nbsp; I was riding earlier today, and it certainly feels much better under braking.&nbsp; Clever German Twonks lol.&nbsp;


Thanks again all.&nbsp;