Anyone know anything about disc brakes?

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  • likely the caliper heating up and the pistons not retracting as well. maybe worth giving the pistons a bit of a careful clean (google sticky piston bicycle shimano or similar)

  • I need to swap SRAM AXS hydro from one identical size frame to another. What's the best way of moving the hydro brakes over? Unbolt the hose at the shifters, try and plug the hose, pull out hose from the back of the frame with the hose still connected to the callipers. Then push the hose up through the new frame and reconnect to the shifters? As I haven't cut the hoses do I just bleed the system then?

    Or is it best to disconnect at the callipers? I imagine it would be easier to feed the hose down the frame rather than up, but from what I've heard its better to leave the callipers connected and disconnect at the lever?

  • i'd imagine you need to replace the 'olives'

    aliexpress copy of park tools internal cable kit is decent or floss and a vacuum cleaner

    1. Removing at the levers is best. They have a connectamajig which seals the lever and therefore DOT doesn't piss out everywhere.
    2. You probably won't be able to seal the hose, but keeping the end up means you should lose too much fluid.
    3. You can cut the olive off (red bit) if you're careful and re-use the barb, but if the holes in your frame are big enough, leave the olive on and re-use them both.
    4. If you're not careful, cut the whole lot off, losing about 1cm of hose length and re-install a new barb. Or if you're feeling pro, use a Reverb Barb to seal the hose when you're maneuvering it.
    5. You might not need to bleed afterwards, especially the front one if you're careful. Only squeezing the lever will tell you this.
  • Hot tips thanks @amey @chiroshi

    It looks like the frame holes (SSEVO) are 'just' wide enough to allow a connectamajig through, so I'll try leaving them on and plugging back in if reusing them wont result in fiery death.

  • Very unlikely (at least the fire bit)

  • Another tip to reduce the loss of fluid is to unbolt the caliper and make sure it drops as you pull the hose through the frame, so that gravity is trying to keep the fluid from siphoning out.

  • If you're moving an internally routed handlebar to another frame I'd disconnect the calipers, if you using a new bar, or externally routed unplug the shifters.

  • Sorry for the dredge but I'm having exactly the same issue with an 8070 lever. It doesn't seem to spring back as far as it should (has quite a bit of play at the end of its return travel) and braking has got progressively worse over the last few weeks.

    Tried to bleed it but just can't push fluid up from caliper to cup, I've pushed quite hard on the syringe but it feels completely blocked. When I press the lever, fluid flows out of the caliper so it seems like there's a block between the master cylinder and the reservoir in the shifter rather than the hose/connectors. The free stroke adjust also doesn't do anything as you mentioned.

    Was your fix as easy as removing the shifter from the bars? Any idea what this did to free the blockage? Has it been ok since?


  • I’ll try to elaborate tomorrow, but essentially yes. And it has been fine since.

  • That's a huge relief to hear! Was worried something might have snapped off inside and jammed it up. I'll try detaching it from the bars but if you have any further details or clues, that would be really helpful.

  • Re reading my post and thinking back, there was not much more. I used the plastic bit dangling off the bleed hose to secure the tube on really tight to be able to force the liquid through. I removed the lever and all the hose from the bars so that I could move it around freely. Not sure exactly what sorted it though.

    I would also try and (carefully) put the freestroke and reach adjustment in a neutral position. I read somewhere that in certain positions it can cut off or limit the flow within the lever.

  • Right, just unwrapped my bar tape and had a mess around with it. As soon as I unclamp the shifter, all play in the lever is gone! Once I reclamp it and pump the brake a few times, it comes straight back. Repeated this a few times to confirm.

    I have the hoses attached under the tape on my Canyon Aero bars with electrical tape and I wondered if clamping the shifter was pulling the hose so I clamped the shifter higher up the bars to give the hose some slack, and, as if by magic, no play :)

    I won't have time to try a bleed until the weekend but I'm fairly confident that it will be ok now.

    My guess from how much bar tape was bunched up under the front of the shifter is that I've hit a pot hole and the shifter has moved down the bars slightly, pulling the hose with it. No idea why this would cause the symptoms that we both experienced though I'm so glad I found your post!

  • Glad you got it sorted. Still don't really get what was causing it as my hose run was smooth, no kinks etc.

  • Thanks for all your help. There's no kinks on my hoses either (they're still taped in the same place).

    No idea how this stuff really works but I wonder if pulling at the hose outwards of the shifter causes some kind of vacuum in there that pulls the 'cover' between the reservoir and the master cylinder shut? In my head this cover springs back against the shifter when it's released so when it's permanently pulled by the vacuum, the lever has nothing to push against at first creating the play in it. That would also explain why we couldn't push fluid into the reservoir.

  • Get in touch with Canyon.

    I'll say that probably the position of the levers on the bars is applying pressure on the hose or the levers have been over tightened.

  • To be fair, I fixed the shifters to the bars myself when I swapped for a longer integrated stem/bar. There's plenty of hose between the frame and where it'staped to the bars but obviously not quite enough between the taping and the shifter and this pulling on the hose is causing the block inside the shifter somehow.

  • I replaced the pads on my cross bike and the new pads are rubbing on the rotors all the time. I pushed back the pistons with a tyre lever but I still only get about 1 wheel rotation when I spin the wheel. I realigned the callipers which made a marginal improvement but not much. Is there anything else I should do or do I just need to ride them a bit to wear the new pads down?

    (Brakes are sram rival from a few years ago, pads are sram organic pads)

  • Spread the pistons more, I find SRAM don't like to retract but if you can manage to spread them and lightly squeeze the lever on and off a bit they usually go.

  • Cheers, will try again

  • Bring it to your LBS with a 6 pack in hand and ask if they'll have a look at it, you'll probably have to pay for their time too but the beers make things go faster!

  • Always figure out the mechanics favourite beer.

  • Is that a reference to when I've consumed too much limoncello but forgotten?

  • My LBS tried to bleed it, couldn't, and gave it back to me. They came to the same conclusion that I initially did, that something was broken inside the shifter so this forum has been much more helpful!

    I actually bled it yesterday and rode it today, had a few issues with the bleed (pushing the lever all the way in, when opening and closing the caliper bleed nipple for example, seems to block the shifter up again) but I managed it and seems all good now :)

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Anyone know anything about disc brakes?

Posted by Avatar for Sanddancer @Sanddancer