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Spongey brakes-advice please
#1
hi people,
im looking for a bit of advice about my shimano deore hydaulic brakes. i've only been riding on them for around 20 miles or so and i'm aware that they take time to bed in along with the disks. When i pull either lever there seems to be quite a lot of travel before the bite point about an inch or so leaving about an inch between the lever and bar, the rear lever feels slightly spongey but not to bad, the front one is stiffer but still travels about an inch before the bite point. I have tried bleeding them as per shimano's instructions but it doesn't seem to of made much difference. Is about an inch of lever travel right?? i've never had hydraulic brakes before so i don't know, do i need to re-bleed them to make the lever stiffer or is it just a case of letting the new disks and pads bed in? Sorry for all the questions but i'm pretty new to all of this.
any help appreciated
thanks
Si
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#2
My disc brakes also seem to have a fair amount of travel before they bite. Provided they have plenty of stopping power and the lever can't be pulled to touch the handlebar, I wouldn't worry too much.

I think it takes a bit of getting used to if, like me, you adjust your cable brakes so that they start to bite with quite a small amount of lever travel.
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#3
That amount of travel sounds about right for Shimano hydros.

However they shouldn't really be that spongey at that age, and if a bleed hasn't done anything then it's a setup issue.

A quick way of doing this is to loosen the bolts that connect the caliper to the adapter so the caliper can slide side to side a bit. Squeeze the brake lever about 5-6 times and then hold (I'd recommend pushing the pistons back in first, take the wheel off and put a flat screwdriver in between the pad and the piston, push on the back of the pad, NOT the piston, this will reset the piston on the other side, repeat). With the lever held down re-tighten the caliper mounting bolts, and this should minimize any bending of the rotor when the brake is applied and aligning the caliper better, reducing the sponginess.

You won't get rid of all the sponginess in Shimano brakes (but you can reduce it to the stage you won't notice), I've got 2-pot Saints (expensive Downhill brake) and they're still a little bit spongy (though the front one has a braided hose and is a fair bit better). This is in part down to the hose used on the brake, which will expand a little when the pressure builds up, thus making it a little more spongy. Shimano hoses aren't the best out there (though they are better than Avid it has to be said), but as long as it isn't damaged will do the job fine.

In short, try setting up the caliper again. You won't get really get a definite sold bite point on Shimanos (I've had several sets but I now use Avids mainly because I prefer the feel of the levers and the definite accurate feeling when you find the bite point). You may also find the bite point moves a bit further from the bar once you've set the caliper up again.

Oh and by the way it doesn't matter whether pads and rotors are bedded in, that simply determines how much power is on tap, and this will increase as they bed in. Even with poorly bedded in pads and rotors the feel of the lever should not change at all. Get this right and it actually makes it easier to bed the pads in as you can apply more force through the pistons and increase friction (and thus wear, which is what bedding in effectively is)
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