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What Does This Knob Do? Deore XT M785 Brakes

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What Does This Knob Do? Deore XT M785 Brakes

Old 05-14-20, 08:12 AM
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jgf310
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What Does This Knob Do? Deore XT M785 Brakes

Several years ago, I put these Deore XT M785 hydraulic disc brakes on my MTN bike, but I haven't used it much since then - I'm mostly road riding instead.

Anyway, I don't seem to have the manual that came with them.

With my road bike, it seems i can always easily find shimano literature online to help with adjusting and so on - but with these brakes, i have found nothing that identifies this knob...

I know the little screw is the free stroke adjustment - if i understand correctly, it just changes the position of the lever, and how far it travels before the hydraulic brake is activated. I can use it to lessen the "throw", at the cost of moving the lever closer.

I want the brakes to activate sooner.., but keep the levers where they are. I think I need to do something with the hydraulic fluid - add more? - and I am prepared to do that, but first I would like to understand the brakes a bit better.

What does the knob do?

thanks


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Old 05-14-20, 08:48 AM
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It is sort of a dismount button. They were first developed by Astin Martin.
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Old 05-14-20, 09:01 AM
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I believe this allows the lever distance from the bar to be changed - smaller hands, less pull etc.
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Old 05-14-20, 09:08 AM
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Originally Posted by 100bikes View Post
I believe this allows the lever distance from the bar to be changed - smaller hands, less pull etc.
my understanding is that's what the little screw does..., so if that's true, then this knob must do something else...
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Old 05-14-20, 11:41 AM
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Originally Posted by jgf310 View Post
my understanding is that's what the little screw does..., so if that's true, then this knob must do something else...
the little screw adjusts the free stroke of the lever before the brakes engage. The knob adjusts the reach to the lever.
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Old 05-14-20, 02:58 PM
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The screw changes how far you need to pull the lever (distance from fully release lever to brake engagement).

The knob changes WHERE that range of motion takes place (closer of further from the bar.)

The latter (knob) can easily be messed with and as long as the lever does not hit the bar, just go with what feels good.

The former (free throw) is going to be limited by pads dragging. The shorter the free-throw, the less the pads retract from the rotor, and the more prefect everything needs to be for the pads not to drag.

Last edited by Kapusta; 05-14-20 at 03:14 PM.
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