Anyone know anything about disc brakes?

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  • What is the best recommendation for flat bar hydro brakes, ideally a front/rear for under 100 quid?

  • Shimano BL MT501/ BR MT500 can be found for around £100

  • Flat mount GRX caliper with seemingly the correct mounts (all OEM) - doesn't seem to fully sweep the rotor? What gives, do I have 165mm rotors?


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  • You don't want the pads to sweep the edge of the disc, that can cause all sorts of trouble


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  • Inner or outer edge? I've not had such a pronounced area of unused disc before.

  • Inner or outer edge?

    Either. You want the rotor to sweep the entire area of the pad. You could always measure, those rotors might be >160mm over the high points, but if they're clearing the caliper body and pad pins, there's no foul.

  • The rear brake on my cross bike is playing up a bit, it loses pressure frequently, but is rectified by a few pumps of the lever. It's then fine until it's left for a bit, then you have to repeat.

    Am I right in thinking there is probably some air in the system that is the root cause?

  • Sounds like it, if it's shimano whack the bleed cup on and pump it a bit and any bubbles will likely burp out.

  • #fuckingsram

    @andyp Mini-bleeds can be carried on SRAM levers too if you have a bottle of fluid with a nozzle, I find the Fenwicks 80ml work well. DOT isn't very nice stuff though so you have to be a bit more careful than with Shimano.

    https://www.pinkbike.com/news/tech-spotl­ight-5-minute-bubble-bleed-2014.html

  • Yup, what the others said.

    It may help to move any air bubbles to the lever end of the system by holding the bike up towards you and bouncing it on its rear wheel while pulling and releasing the lever.

    The lever will firm up and all the air will all be in one place ready to bleed

  • It’s Shimano, thankfully.

    Thanks all, appreciate the responses.

  • Lemme know if you want to borrow a funnel etc in that case!

  • I've had success getting air bubbles out of SRAM with a syringe on the lever and a bit of pumping and toing and froing with the fluid (ooh eer). Sometimes stubborn bubbles can be guided up by tying the lever down and leaving it higher than the caliper then doing a bit of burping after an hour or 8.

  • Thanks, but I’ve got everything I need. Was just looking for validation that my prognosis was correct.

  • prognosis

    Diagnosis. The prognosis is that bleeding will fix it.

  • Anyone got experience of the Juin tech f1 and GT? F1 is quite cheap in comparison (about half the price) but my brain says 4-pot calipers will be better.

  • I was a fan of my juintechs pre GRX, I'd say they're the best semi-hydros you can get but they're not a patch on proper hydros, never tried the GT ones.

  • Thanks. My problem is I've got a pair of 6870 shifters as well as an 8070 shifter and a couple of ultegra calipers (one of these may also be leaky). LBS told me the shifter was leaky too (only started leaking when they fitted my hope calipers tho)

    So I've got two choices, roll the dice and get another shifter and set a full hydro setup but potentially find both ends have a leak... or juintech.

  • I'd go full hydro if you can but it sounds like you've had a rough time with them.

  • I have the gt's. I now love them but that has been after a lot of time spent getting the right compression less housing and inners. I also Installed galfer pads and rotors. Breaking is so much better than before when I was on standard pads and SRAM rotors.

    There aren't any great videos online to get them set up perfect but their are some good little tricks. Really solid ferrules with a hole just big enough for the brake cable also make a difference

  • Bought an R7070 calliper to replace one with a leaky piston seal, only to find out this one also has a lovely piston leak too. Do I gamble and buy a third Shimano calliper? Whatever I do I think I want it to be ‘official’ and done by the lbs. Both the previous two callipers were bought ‘new and unused’, and installed by me. With this lack of warranty I’ve been left up the creek twice


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  • i may have a couple in my shed, yours if you can collect

  • I’ve got your hydro cutters still! Need to return them to you anyway so maybe I’ll take you up on that.

    I’ve given the bike back to the shop who bled this calliper yesterday (after I installed it the day before but couldn’t be bothered to nail the bleed as it was being a PITA - which I now see why…) so that they can test the calliper and sort it tomorrow. I’m guessing they’re going to charge me for another bleed and a new calliper, I’ll probs just say yes so that it’s just done and dusted. But would love to have the willpower to grab one off you and do another bleed….

  • Thinking about swapping from TRP hyrds to shimano rs505 fully hydraulic system- can anyone advise how much improvement I'm likely to see ?

    My Hyrds have never properly self adjusted so have always been quite a pita.

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Anyone know anything about disc brakes?

Posted by Avatar for Sanddancer @Sanddancer

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