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I have a 10-year old bike, fitted with hydraulic disk brakes. The bike has been actively used for around 4 years only though.

Recently, my brake levers started to have more and more "play" before the bike actually starts braking. A kind of a "dead zone" where nothing happens, just like if there was not enough oil.

I went to the store to fix it, twice, but it keeps coming back. They say something may be stuck ("bourrage" in french, as ugly as it sounds). They told me they bled the brakes, but at this point I'm not sure anymore.

So now I'd like to fix this myself, once and for all.

The brakes are the only thing I've been afraid to fiddle with, so far, so that's why I'm coming here for advices.

Is there any "fixing your hydraulic disk brakes 101" or equivalent? A guide I could follow to check things in order. Shall I check brake pads first, then oil, then... A flowchart would be lovely!

tl;dr: What to check first to fix hydraulic disk brakes?

  • I went to the store to fix it, twice, but it keeps coming back. Can you clarify that statement? Who fixed it? What did they do? Why does it come back? – Ritch Melton Jun 10 '14 at 15:07
  • Define "play". Absolute free play or just a little resistance. If you have air in the line then it will be soft and you will need a longer pull (air is compressible). You may need to bleed the brakes. How to bleed varies and may require special tools. See the instructions for that specific brake. – paparazzo Jun 10 '14 at 15:29
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    I have a book I can recommend by a guy called Lennard Zinn, which gives a 101 in most everything to do with a bike (including disk brakes). There is a road bike version too, which I can also recommend. And by the looks of things he's done a TT one. Zinn & the Art of Mountain Bike Maintenance. I mean obviously you've got the expense of the book, but its a great reference if you're going to be doing your own maintenance – PeteH Jun 10 '14 at 19:59
  • "A kind of a "dead zone" where nothing happens, just like if there was not enough oil." Check oil level and bleed the brakes. And PeteH that is book is not just informative it is entertaining. – paparazzo Jun 10 '14 at 23:28
  • It would also likely help if you said what model of brakes you were running - certain models are more fidgety than others and tend to go out of spec in certain ways. – Batman Jun 11 '14 at 5:57
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If they are SRAM/Avid hydraulic brakes, you're screwed. The DOT 5.1 fluid attacks the o-ring seals, and makes constant issues. Storing the bike for a while, upside down or vertically, will also cause issues. If they are Hayes or Tektro, same deal with the the DOT 5.1. This means don't spend money on them, replace with a Shimano M596 or better. They use mineral oil, which is much better with rubber, moisture, and expansion. They also have the fewest issues of any other mainstream product out there, by far.

Now, SRAM currently allows a no-questions asked full replacement warranty with all current models. I don't recall how far back it applies. If 10 years, maybe not. But, still worth a try. Ask a reputable LBS to make the call to SRAM on brake warranty. Thing is, you're getting another SRAM brake, which will do the same thing again.

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    Tektro is mineral oil, not DOT3/4/5.1. – moshbear Aug 11 '14 at 1:08
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    They are now, thankfully. – Philip Pugeau Aug 11 '14 at 1:38
  • The problem with Avid elixirs is a design flaw that traps air (finally admitted this year) which make them difficult to bleed, but if bled properly are a very good brake. Avid use different seals to Shimano, each are suited to the type of fluid and neither is better or worse on their respective seal. DOT is harder to work with but more reliable. – DWGKNZ Aug 11 '14 at 2:09
  • Is that what it was, all this time? So simple. Well, I've seen way more issues versus Shimano, across many years of re-engineering. Especially with the front brake. Hopefully now they've solved the issue. – Philip Pugeau Aug 11 '14 at 4:12
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The seals will age over time, and air will leak in. Surprised (but not so much) that your LBS didn't suggest you have the seals replaced the second time you showed up. Undoubtedly available on Amazon.

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