The hydraulic brake caliper on my bike is slightly out of alignment. It's not fully rubbing, it more or less looks like the slight rub picture here - https://www.parktool.com/en-int/blog/repair-help/hydraulic-disc-brake-alignment. It doesn't appear to affect the bike's performance, except that occasionally there's a slight noise.

I'm a bit worried that as my brake pads wear out this might mean that there is enough clearance for one of the pistons to fall out completely/lose braking pressure. i.e., if one of the pads is further out than the other, and the brake pads are sufficiently thin.

Does anyone know if this is a possibility? I don't have a torque wrench so I'm a bit worried about properly reattaching the caliper if I align it.

Thank you

  • Getting the right torque is not critical for this application. By the way, when compared to the cost of new brake pads (due to early wear), the cost of a torque wrench is really not that crazy.
    – MaplePanda
    Commented Jul 27, 2022 at 5:11

1 Answer 1


No, no way the pistons can come out if the wheel is mounted, no matter how worn the pads are and how out of alignment the calipers are.

Misaligned pads cause extra pad wear and poor performance until the pads are worn to match the misalignment, but in doing so you loose a lot of useable miles. If you pads only have a few miles on them, I encourage you to align the caliper properly.

This job can be done without a torque wrench without much risk if you have a feel for correctly tightening bolts and don't go at it like a gorilla with a spanner. Bolts should be 6-8Nm (some specs go up to 10Nm), a hex wrench 100mm long needs about 10kg towards the end - enough to leave a small but not painful dent on the palm of you hand.

  • Great, thank you! The current pads are already quite asymmetrically worn so I think I'll wait until I replace them before aligning it, but I'm glad to hear they're not going to fall out on me. Commented Jul 27, 2022 at 6:05
  • 1
    "a hex wrench 100mm long needs about 1kg towards the end" -- hmm, is that right? i believe that's just 1Nm
    – Robert
    Commented Jul 27, 2022 at 17:35
  • Thanks, you are correct - typo...
    – mattnz
    Commented Jul 27, 2022 at 21:18

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