A most perplexing problem: self re-contaminating brakes
Discussion
Evening all, I have an odd problem with the front brake on my bike.
I have a tektro hydro disc setup, which was working fine (if a little fade-happy due to super hard pads) until I left my bike in the indoor bike storage at my halls over the easter break. The first time I rode it when I came back, there was practically zero retardation unless I pulled the lever with all my might (by this, I mean the lever was still perfectly firm - it was a lack of friction at the business end), and despite it being dry the disc made the juddering squeak one would expect when they are wet on a rainy ride.
I thought this was odd, so I took the pads out, sanded a few thou off the surface, and thoroughly cleaned the disc with muc-off alcohol. This did precisely nothing to fix the problem on the next ride out, so I moved to plan B. I acted as if I was bedding in a new set of pads, and went for a run down the steepest hill in bristol. I got the disc and pads so hot by dragging the brakes with occasional hard squeezes, that I lost all friction whatsoever and had to stop with the rear.
Once everything had cooled, the problem had gone away and I had a nice amount of bite again. All was fine for about a week, during which I rode the bike once a day.
However, after a 4 day gap from riding I went out again and the problem had returned. The steep hill bedding in trick worked again. Rode a few days in a row, fine. Left it a bit again, problem returned and fixed with the same method.
My current theory is that something is contaminating the braking surface, for some reason only on the front, at such a slow rate that it only becomes a problem if left for a few days. But my question is what could be doing this? There is no visible evidence of a fluid leak, and the lever is still firm. whatever it is is obviously burnt off with a good bedding in. The bike is stored at all times in a warm, dry indoor bike shed.
Short of someone coming along and oiling the front brake for me, can anyone think what could be causing this as it is getting on my nerves!
I have a tektro hydro disc setup, which was working fine (if a little fade-happy due to super hard pads) until I left my bike in the indoor bike storage at my halls over the easter break. The first time I rode it when I came back, there was practically zero retardation unless I pulled the lever with all my might (by this, I mean the lever was still perfectly firm - it was a lack of friction at the business end), and despite it being dry the disc made the juddering squeak one would expect when they are wet on a rainy ride.
I thought this was odd, so I took the pads out, sanded a few thou off the surface, and thoroughly cleaned the disc with muc-off alcohol. This did precisely nothing to fix the problem on the next ride out, so I moved to plan B. I acted as if I was bedding in a new set of pads, and went for a run down the steepest hill in bristol. I got the disc and pads so hot by dragging the brakes with occasional hard squeezes, that I lost all friction whatsoever and had to stop with the rear.
Once everything had cooled, the problem had gone away and I had a nice amount of bite again. All was fine for about a week, during which I rode the bike once a day.
However, after a 4 day gap from riding I went out again and the problem had returned. The steep hill bedding in trick worked again. Rode a few days in a row, fine. Left it a bit again, problem returned and fixed with the same method.
My current theory is that something is contaminating the braking surface, for some reason only on the front, at such a slow rate that it only becomes a problem if left for a few days. But my question is what could be doing this? There is no visible evidence of a fluid leak, and the lever is still firm. whatever it is is obviously burnt off with a good bedding in. The bike is stored at all times in a warm, dry indoor bike shed.
Short of someone coming along and oiling the front brake for me, can anyone think what could be causing this as it is getting on my nerves!
I would start by changing pads, you might have completely cooked them. Also you may have oil on the rotor in the vent holes, as they get hot this will migrate into the pads. You might have oil around the piston seals which again will migrate when hot. Its a problem I had on Xt brakes when they were a few years old. I ended up stripping the calipers, bleeding new rotors and pads.
in short, your pads are shot. I doubt there is any contamination, just their performance level has hit the cliff edge, particularly if you have to get them hot before you feel anything. At a guess, the compound used to hold the pad together needs a heat cycle before it will perform. Same principle as super soft kart tyres really.
I'd be surprised if OEM pads werent rock hard sintered pads that are designed to last for ages. Try some organic pads which in general, have greater inital bite but will wear out a bit quicker.
Also given the winter we have had, constant freezing conditions and thaws, a fluid change might be in order?
I'd be surprised if OEM pads werent rock hard sintered pads that are designed to last for ages. Try some organic pads which in general, have greater inital bite but will wear out a bit quicker.
Also given the winter we have had, constant freezing conditions and thaws, a fluid change might be in order?
Edited by anonymous-user on Wednesday 8th May 11:05
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