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Disc brake virgin.....
 

[Closed] Disc brake virgin... how do I tell if I need to bleed?

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[#433219]

Fitted some new SLX brakes to my bike at the weekend, and shortened the cable hoses, taking care to try not to introduce air to the system. The only thing is, having never used disc brakes before I have no idea whether I need to bleed them or not. The lever feels softer than my old v's, but I really have no idea whether it's 'right' or not. They seemed OK on a test ride, I guess. Any tests I can do, short of finding a descent, cooking the brakes and killing myself?


 
Posted : 30/03/2009 9:07 am
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If the brake feels spongy...ie when you pull the lever you can't 'feel' the point where the pads make contact with the rotor then you probably have air in the system. Sometimes the brakes can feel OK one minute the next spongy depending where the trapped air is in the sysetm.


 
Posted : 30/03/2009 9:13 am
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Hmm, I can definitely feel the pad contact but it still feels a little spongy compared to V's for example. I guess I could have introduced air to the system, plus I don't know how carefully they were set up by Wiggle in the first place.

Next question... where can I get a little bit of plastic tube for bleeding, without buying Shimano's bizarrely expensive bleed kit?


 
Posted : 30/03/2009 9:23 am
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Pet shop (tubing for fish tank air feeds), car spares shop (windscreen washer tubing), model shop(IC engine fuel tubing).


 
Posted : 30/03/2009 7:35 pm
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Halfords does the tube (for windscreen washers) and the LHM mineral oil (labelled as citroen steering oil IIRC).

The SLX brakes do feel a bit more spongey than my LX discs. Think it's down to the servowave action of the levers.

Also, they were very difficult to bleed properly for some reason (much harder than LX or Avids). I would get a syringe and try a bottom up bleed if possible.


 
Posted : 30/03/2009 7:54 pm
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I think the problem bleeding these may be down to the transfer port between the reservoir and cylinder being on the side rather than the top, thus not letting air rise naturally into the reservoir. (don't really know how to solve it though, pointing the lever downwards is probably your best bet if possible)


 
Posted : 30/03/2009 8:02 pm