Author Topic: Braking system  (Read 505 times)

0 Members and 3 Guests are viewing this topic.

Offline DougD

  • XR Member
  • **
  • Posts: 35
  • Town / City: Sri Racha
  • Country: th
Braking system
on: November 20, 2021, 06:58:51 AM
Hi, I find the rear brake to be rather useless. Its contribution to all out slowing the bike nearly none. Now I understand that the front brakes do all the heavy work. Fine. But at times trail braking for example into a tight corner lightly with the rear brake may help a bit with turn in again particularly on the tight stuff. But the feel and usefulness is absent. I routinely use the front brake only the vast majority of my riding. Some youtube reviewers have commented about "linked braking" on the F900XR. I can't find anything about this. In other bikes I've owned with linked brakes grabbing the front brake would divert some pressure to the rear for more balanced braking just using the front brake lever. Does the F900XR have linked brakes? And if so how do they work? Thanks,,,

Online rcb78

  • XR Master
  • ****
  • Posts: 733
  • Country: us
Re: Braking system
Reply #1 on: November 20, 2021, 04:11:33 PM
If your referencing, I think his name is Scott, on the Nothing to Prove YouTube acct, he's wrong.  That's the first place i heard it mentioned and even though i contacted him directly he's never addressed it.  Linked braking is a pretty big selling point, big enough for a manufacturer to brag about it in marketing.  Our bikes do not have it.  The only link is how the ABS has control of both independently (2 channel) and can release the rear if you grab to much front due to the rear lifting, this is NOT linked braking, just normal 2ch ABS function.
I'm not sure why everyone thinks the rear brake is so bad  It's not grossly overpowered like in some bikes where just tapping it will skid the back tire but that doesn't mean it's not powerful enough.  Turn off the rear ABS and try for yourself.  It does seem to build power at a more extreme angle for the ankle making you point your toe more, but that's a real easy fix with a 'pedal enlarger' that effectively raises the surface about 10mm.
I would also recommend swapping out the rear pads to an HH sintered compound since the OE pads are organic.  Sintered has slightly more initial bite making them easy to feel with light pressure.

Offline DougD

  • XR Member
  • **
  • Posts: 35
  • Town / City: Sri Racha
  • Country: th
Re: Braking system
Reply #2 on: November 20, 2021, 04:32:16 PM
Hi, Many thanks for the reply and clarification!  :152: I suspected that linked braking was not incorporated into the F900XR brakes. I recall my Moto Guzzi grabbing the front brake did something like 70% to one front rotor and 30% to the rear and the rear pedal provided more to the rear and the rest to the other front disc. But my memory may not be perfect on that!  :033: What you describe is helpful and the suggestions on brake effectiveness with larger foot attachment and different pads, sound reasonable. As an example when testing I released the front brake while coming to a stop light relying solely on the rear brake and nearly hit the car in front of me! It really didn't offer much at all. Perhaps I should have taken up more of the travel of the foot brake lever more aggressively. The switch for the canceling of the cruise control at the foot brake lever seems a bit overly sensitive at times so I don't want to mess around with the lever too much. In any case its not a huge issue but still a bit curious as this is not my first BMW but strangely different. The knowledge on this board is really cool.  :062:

Online rcb78

  • XR Master
  • ****
  • Posts: 733
  • Country: us
Re: Braking system
Reply #3 on: November 20, 2021, 04:57:52 PM
Rule of thumb is that only 90% of your power is from the front so you can't expect much from that leftover 10%.  Like i said, try disabling the rear ABS (assuming you have Dyn Pro) and see what happens.  I think you'll be surprised at how easily you can lock the rear wheel,,, and still not come to a stop. 

Offline DougD

  • XR Member
  • **
  • Posts: 35
  • Town / City: Sri Racha
  • Country: th
Re: Braking system
Reply #4 on: November 21, 2021, 07:24:04 AM
Hi, I just went for a short ride and did precisely as you suggested. In Dynamic Pro with the ABS disabled I was able to lock up the rear brake and leave a nice fish tail looking black line and scare a few stray dogs! The power just as you mentioned sufficient enough to provide the braking power expected and easily lock the wheel. (Not that I ever doubted you!)  :001: But where then does the deception lie? Its best described I think as my right hand and right foot feel like they're operating two different motorcycles. This come from the quite different characteristics on the lever responses. Bottom line? Just ride it as normal and forget it! My right foot will learn to adjust to the longer throw and different pressure compared with the front brake lever. Overall of course the bike stops exceptionally well and I just have to understand the back brake is contributing (appropriately) probably more than I think. Once I train my foot to accept the further travel and added pressure.  :138: All good. And thanks once again for the education! An old dog can learn new things!  :046:

Online rcb78

  • XR Master
  • ****
  • Posts: 733
  • Country: us
Re: Braking system
Reply #5 on: November 21, 2021, 05:26:36 PM
If I were to guess, manufacturers have increased modulation by spreading the power of over a longer stroke to give a more precise control at the rear.  This will make it easier to control the rear brake and less likely to slide out and low side in a turn.
If you can readjust your foot position to keep it away from the pedal, the enlarger really does make it better.  It moves the bite point higher up into the sweet spot for me.  My boots are size 13/48, if i can make it work then anyone should be able to.

Offline DougD

  • XR Member
  • **
  • Posts: 35
  • Town / City: Sri Racha
  • Country: th
Re: Braking system
Reply #6 on: November 22, 2021, 03:35:36 AM
Should be easy to follow in those footsteps!  :001:

Offline MotoJoro

  • XR Pro
  • ***
  • Posts: 86
  • Town / City: Sofia
  • Country: bg
Re: Braking system
Reply #7 on: November 22, 2021, 03:12:00 PM
There was another post with the same question - yes the rear break is not much but tell me one bike in that class which has "good" rear one?
I tried my wife's Tuono 660 and I have better chance stopping by the drag from hitting flies with the helmet than with the Aprilia's rear.

Online rcb78

  • XR Master
  • ****
  • Posts: 733
  • Country: us
Re: Braking system
Reply #8 on: November 22, 2021, 05:02:19 PM
I've ridden a few cruisers that had excessively powerful rear brakes, and I did not like them.  In a fwd control design it was way too easy to stab the pedal and lose the rear end.  My wife's current cruiser (Kawi Vulcan S) has a rear brake that feels about the same as my XR and it's perfect.  So easy to control with near perfect modulation.

Offline patgm

  • XR Pro
  • ***
  • Posts: 87
  • Country: us
Re: Braking system
Reply #9 on: November 23, 2021, 06:29:38 AM
*Originally Posted by rcb78 [+]
If your referencing, I think his name is Scott, on the Nothing to Prove YouTube acct, he's wrong.  That's the first place i heard it mentioned and even though i contacted him directly he's never addressed it.
I like Scott's channel, but I commented on that video about this and he replied but was pretty dismissive, sent me a link to a wikipedia page about linked brakes. I replied saying that there is a section on "integral ABS" in all of the R, K, and S-bike owner's manuals, and that no such section exists in the F900R, F900XR, or F850GS manuals, he didn't reply a second time.

I've never had any trouble with the throw of the rear brake lever, the feel, or the effort needed to modulate it. The varied experiences that people are having makes me wonder about the quality control of the rear master cylinder. 
My complaints with the rear brake are:
ABS gets involved too soon in every mode except Dynamic Pro - Disabled.
It makes a lot of bothersome noise when cold under light to moderate brake pressure. I am hoping that one can be remedied with better pads.

 



strongminded