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Braking distance with rear brake is three times longer than with front brake. So, the more you use rear brake the earlier you have to brake.
If you can use rear brake, without braking earlier, it just indicates that your current front brake usage is very inefficient. And that is one reason why your lap times are slow.
Also, to add to that, your BMW mechanic ripping you off charging twice the money's for same work.

All in all quit biking.
 

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Discussion Starter #82
@speedfinn
You clearly don't use the rear brake, nor understand its application. It does not work for everyone. Again, it's not about stopping power. Are you gonna keep dodging the question about load transfer, front, and rear?

Summary for those those looking for a TBS solution:
I have contacted race shops in US and UK, most of kits don't retain foot brake lever, except for IMA TBS using two MCs.

IMA does not come with complete hardware (tubes, banjos, etc...). I wanted a complete set, Accossato mounts to bar, fork seems to be a better option. That left me with three options:
Hel, Speedycom, and Sato. Hel makes quality brake lines, their fittings are used by L74 underslug caliper race kit I am using, so decided to go with Hel.


Ian at speedycom (setups up BSB bikes on GSXRs) explained well on why not to retain foot lever, aside from superstock race rules, a single line from TB MC to rear caliper will have better pressure (as good as foot brake) without going through T fittings & 2nd MC. Few riders use both foot and TB, most use TB only. He pointed me to various dirt bike TB kits, most of which don't retain foot lever either. SPEEDYCOM THUMB BRAKE

Danilo Petrucci confirms thumb brake is needed for taller riders that use the rear brake. So I'm giving this a shot since it's a new build. Worst case, I remove TB, put back foot brake.
 

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Of course there is a connection. We are using the rear brake to reduce load on front, help tighten the line, we are not using it for stopping power.

For the third time: you have not provided an answer. I have answered your question.
You clearly don't use the rear brake, nor understand its application. It does not work for everyone. Again, it's not about stopping power. Are you gonna keep dodging the question about load transfer, front, and rear?
Yeah, physics does not work for everyone, especially if you do not understand physics.

If you want to tighten the line, you must brake/ use stopping power/ decelerate, with front brake or rear brake, and deceleration will reduce load on rear and increase load on front.

There are also small additional forces related to braking while turning:
If you use rear brake, the rear brake force "generates a torque which tends to align and stabilize the motorcycle". So, the actual rear braking force causes the motorcycle to go straight forward, not tighten the line.
vs
"the torque generated by the front braking force and the inertial force tends to yaw the motorcycle". So, the actual front braking force helps the motorcycle to turn, and tighten the line.

Fourth time the same question:
So, you do not see any connection between front brake, load transfer and rear brake?
 

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Discussion Starter #86
If you want to tighten the line, you must brake/ use stopping power/ decelerate, with front brake or rear brake, and deceleration will reduce load on rear and increase load on front.
Wrong. Rear brake reduces load on the front.

Yes, front brake could help yaw the bike. But the part you are missing is that rear brake is used after the bike lean is initiated (not full lean nor full up right).
Braking pressure is inversely proportional to lean angle, substituting trailing front brakes with rear helps not overload the front. Remember the rear brake only works at certain corners, not saying to use it at every corner.

I have already answered your question, repeating my answer won't change it. It could be the wrong or right answer, that's why I asked so others can share their opinions.

@vneyer Qnuim is nice, but wanted the push not pull type thumb brake, while leaned over push type works better.
 

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Rear brake reduces load on the front.
Wrong.

So the real problem all along has been that you really do not understand the connection between front brake, load transfer and rear brake.

Try to understand that braking with front or rear brake causes deceleration, and deceleration causes load transfer, and load transfer increases load on front.

Remember the rear brake only works at certain corners, not saying to use it at every corner.
Yeah, physics does not work for every corner, especially if you do not understand physics.
 

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Discussion Starter #89
Try to understand that braking with front or rear brake causes deceleration, and deceleration causes load transfer, and load transfer increases load on front.
This whole time I'm referring to corner entry, a given apex requires a certain corner speed, to get there deceleration is needed assuming entry speed > corner speed; Let's say only the front brake is used, under braking bike forks compress, increasing load on front. More lean angle, causes forks to compress, more load on front. When the rear brake is applied, rear shock compresses, reducing load on the front. The last section of trail braking with front brake can be replaced with rear brake. For certain corners that is more stable, less risky, less load on front than using front brake alone.

Load transfer is happening all the time while on a bike, just needs to be smooth. Going by your logic, even at 100% throttle or brake, uneven track surface will also cause load transfer. So what? A simple body weight shift by rider does the same (move on the seat).

The front needs some load to grip, it's abrupt over/under load that causes front to lose grip (I have crashed from both, roll off the throttle at lean abruptly, not touching brakes, front will tuck). So Dr. Physics, what am I missing here?

What do MotoGP riders do with thumb brakes?
For actual on track camera footage, many videos on YT. Here is WSBK Yamaha tech manager covering it:
 

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Here are a couple questions to consider:
1) How would the bike's trail be affected by the rear brake? More trail, less trail, no change in trail?
2) If the trail does change, how would that change of trail affect the bike's line mid-turn? Tighten line, widen line, no change in line?
 

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Unfortunately I think it matters not the post speedfinn will attack zoo.

Others chiming in get ignored
 

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When the rear brake is applied, rear shock compresses, reducing load on the front.
Wrong.

Try to understand that braking with front or rear brake causes deceleration, and deceleration causes load transfer, and load transfer increases load on front.

That physical fact does not change, no matter how many times you repeat your delusion.
 

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Unfortunately I think it matters not the post speedfinn will attack zoo.

Others chiming in get ignored
Braking with front or rear brake causes deceleration, and deceleration causes load transfer, and load transfer increases load on front.

Do you agree or disagree?
 

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Thanks for the video, z00

If the rear brake (conventional or thumb operated) is a worthwhile tool for WSBK riders, it certainly is certainly something we should consider as well. If the rear brake were worthless, WSBK and MotoGP riders would not use it.

Also I, for one, would like answers to Dylan's questions. I do not know and would like to learn.

Speedfinn's incessant shouts of "wrong" add nothing to the thread other than noise.
 

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Braking with front or rear brake causes deceleration, and deceleration causes load transfer, and load transfer increases load on front.
Interesting, I get what you’re saying. Is the load transfer happening when your body is being sent forward from the rear breaking?
 

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As a new guy on the forum, it's amazing the amount of bickering I see going back and forth.

I think we can all agree that it's a nice tool to have. If wsbk and Moto GP utilize it, then it's something to consider. What I also take from this is that it's riders preference. Some use the rear, some don't, and that's even in the big leagues.

So let's all get along and enjoy these amazing machines, yeah?
 

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Discussion Starter #98 (Edited)
Try to understand that braking with front or rear brake causes deceleration, and deceleration causes load transfer, and load transfer increases load on front.
My answer is detailed to explain my rationale. Stating what you said again without elaborating is not helping, so either elaborate, or there is no point of going in circles.

Here are a couple questions to consider:
1) How would the bike's trail be affected by the rear brake? More trail, less trail, no change in trail?
2) If the trail does change, how would that change of trail affect the bike's line mid-turn? Tighten line, widen line, no change in line?
Good questions Dylan! I'm no geometry/suspension guru by any means.
1- Assuming you mean rear trail (see pic). Since the rear rises with acceleration, it would pull down under rear braking (force is applied to rear brake caliper instead of pavement). So rear trail increases.

2- With increased rear trail, bike would hold the line better mid turn (widen = longer wheel base = stability).

Watching a K67 swing arm angle on dyno, validates what I'm saying.

Thoughts?


214663
 

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My answer is detailed to explain my rationale. Stating what you said again without elaborating is not helping, so either elaborate, or there is no point of going in circles.
Simplified model:
Wheelbase 1400 mm
CoG height 700 mm
Weight distribution 50% / 50%
Friction coefficient 1.0

1. When traveling at constant speed:
Load on rear 50%, load on front 50%
Do you agree?

2. Maximum front braking:
Load on rear 0%, load on front 100%
Do you agree?

3. Maximum rear braking:
Load on rear 33.3%, load on front 66,7%
Do you agree?
 

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I don't agree with the loading. Your tieing max brake force being directly portion to load it's not

Unless your rear is off the ground you don't have 100% of the load on the front.

If you start with 50/50 and add rear brake would it not be more like 65r/35f
 
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