My bike has disc brakes connected to the lever by cable. I've found I've been tightening the screw by the lever more and more to the point that there's not that much more room to tighten.

  • Are your brakes hydraulic, do you have a make or model of the brakes to help us work out what might be wrong. Even a pic would be a great help. – Dan K Aug 15 '19 at 9:22
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    @DanK it has to be a cable system, hydraulics don't have an adjustment screw (barrel adjuster) – Andy P Aug 15 '19 at 9:32
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    @Andy P good point, I'm having a proper blonde day today – Dan K Aug 15 '19 at 10:06
  • Then again, TRP HY/RD brakes have both cables and hydraulics, and shouldn't have the cable over-adjusted or something – Swifty Aug 15 '19 at 18:51
  • The underlying reason is "general decline". Why should brakes be different from ourselves? – Peter - Reinstate Monica Aug 16 '19 at 13:01

On most cable disc brake systems there's a moving pad and a fixed pad. The moving pad presses against the rotor and bends it slightly towards the fixed pad. The rotor is made of rather springy steel, and is probably where the feeling you experience comes from.

The barrel adjuster only addresses wear to the moving pad, but the fixed pad also wears in use. The rotor has to bend more to contact the worn fixed pad. This means that tightening up the fixed pad is necessary (about every other time I tighten the barrel adjuster on mine, but it depends on the pads and mechanism). It can be a bit of a pain as it's not very easy to get at.

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    I would expand the answer slightly, to indicate the barrel adjuster only moves the moving pad closer to the rotor. Over time the gap between the fixed pad and rotor will get larger through wear if the fixed pad isn’t adjusted as well. This is why the OP noticed the brakes were more squishy (i.e., more rotor flex) – Rider_X Aug 15 '19 at 16:35
  • @Rider_X good thinking. I've obviously spent too much time fiddling with them to explain properly. – Chris H Aug 15 '19 at 16:51
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    In most cases the moving pad also has an adjuster. The barrel adjuster whould not be used to adjust for wear. parktool.com/blog/repair-help/mechanical-disc-brake-alignment – mattnz Aug 16 '19 at 0:47
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    @mattnz one very common (and often copied) design is the BB5 which does use a barrel adjuster for the moving pad, mounted on the moving caliper. So the barrel adjuster might or might not be the right way to adjust the moving pad. If the OP tells us which model I could be more specific. Until then I don't won't to suggest that what they've done so far is incorrect – Chris H Aug 16 '19 at 6:02

There are two reasons why this happens with cable disc brakes.

The first is that the pads wear, and since cable systems are not self adjusting, you need to tighten the cable to bring the worn pads back closer to the disc.

Secondly, cables stretch over time, which again requires you to tighten the screw to take the slack out.

If you've reached the point where there is no adjustment left, then you need to check the brake pads don't need replacing. If the pads are good, then you'll need to un-clamp the cable at the caliper and re-tension it that way.

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    I would stress that in some mechanical disc brakes it is not advisable to tighten the cable. One should instead use the pad adjusters to bring the pads closer to the disc, especially when the change is in the pad wear and not cable loosening. – Vladimir F Aug 15 '19 at 12:28

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