Hope Mono 4's

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  • Hope Mono 4's
  • DickBarton

    The original M4s were intended to do that – small pistons first then with more lever pull the bigger pistons would work.

    Give them a service/bleed and they should be fine.


    They're not high maintenance at all. Quit fiddling with them and judge them by how they work when they're used as intended. If you find that you have problems with drag or noise, then check the operation of the seals. Like all Hopes, they are eminently serviceable.

    To save me repeating myself, here's a link to the caliper overhaul, which begins with a short description of how to clean pistons and seals.

    The small/ large piston is to even out pad wear – leading edge of a long pad wears more so putting different size pistons evens this out. All 4 should move at the same time – but a simple clean and lube and all will be fine

    Love Tubs


    Just purchased used Mono M4 F&R, in vgc. Now I've actually thought about the purchase I'm not entirely convinced it was…erm, the best choice…they seem OK but can't help thinking 'high maintainance'?
    I'm assuming the small-large piston combo concept was to 'smooth' power delivery to the disc (is this 'modulation?)? During initial 'play-fiddle-disassemble' session it was clear that the smaller pistons were moving way ahead of the 'seemingly stuck' larger ones?? However, upon fitting the larger ones came into play…I think?

    Anyone still using these units? Tips would be welcomed 🙂

    Perhaps a service will restor mechanical equilibrium?

    Love Tubs

    Thanks all, obvious now you've pointed it out ,,, I aint no dufus ? Cheers for the linky too.




    if your comment is true, how come the Tech M4 has the same size pistons?

    or did you make it up?

    Love Tubs

    perhaps his logical step transferred over from brake pad wear on rims, as these are positioned off parallel in order to reduce squeal and the like…as you know.

    Maybe the leading edge wears due it being the first edge taking the dust build up?? I have no research to back that up btw.

    Shimano XT 4 pots from the same era had pistons all the same diameter and didn't suffer excessive pad wear with the same pad profile as M4's.
    When brakes were not made to such high tolerances, big pistons would twist in the bores and stick. I think 4 pots were introduced to give the same piston surface area without sticking in the same way as large 2 pots, and different companies had their own ideas for curing this problem. Shimano used 4 the same size, and Hope went with different sizes.
    Tech m4's are all about piston surface area/power. more area = more power.

    From motorcycle brakes – this was the explanation I read when multi piston brakes came out. Could be marketing bollox but seems to have some logic behind it.

    Premier Icon Jase_MK

    No probs here with a Mono M4. Have the M4 up front and Mini at the back and to be honest it's usually the Mini that I'm fiddling with. The brakeset is four years old now and has been fitted to three bikes and all I've done to the M4 in that time is change the pads a few times and bleed once when I had to do something to the lever.

    Premier Icon Onzadog

    Unless all my university engineering degree has deserted me due to lack of use, I'd say if the small pistons are moving first, it needs a service. As you pull the lever, you increase the pressure in the system. The larger pistons obviously have the larger surface area so respond more easily to the pressure in the fluid. F=PA. Or is the fact that I've only just woken up showing through? I also thought the big pistons were at the front to lead the pad into position to give a more gradual application of power. Oddly enough, the two 4 pot brakes before it, the DH4 and the E4 all used 4 matching pistons in each caliper.


    I've had a set for six years and counting. No problems at all, the bleeding procedure is dead easy and needs to be done every couple of years or so. As for pad wear, I've managed to eke out just over a year from each set of pads.

    There isn't much to fault, even if you're a total numpty with a spanner (like myself, for example) and you manage to snap a banjo while fitting new brake lines (like myself, for example) then you can pick up spare parts anywhere at reasonable cost.

    Can't fault 'em.

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