Possible to fit bigger discs?

mugensi
mugensi Posts: 559
edited October 2016 in MTB general
My bike has 180/160 (F/R) discs. The front brake is phenomenally strong but the rear not quite as good. The brakes have been bled and the pads are new. I realise with my weight being mostly on the rear and the smaller disc that its not going to be as good as the larger front but wondered is it possible to fit a larger rear disc and space out the caliper to match it?

The rear brakes are Deore A-M615.

Comments

  • cooldad
    cooldad Posts: 32,599
    You can but as 80% (or so, made up number) of braking comes from the front brake, probably pointless. It will just lock up easier. If you can't lock up a 160 rotor there's something wrong with the brakes.
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  • mugensi
    mugensi Posts: 559
    cooldad wrote:
    You can but as 80% (or so, made up number) of braking comes from the front brake, probably pointless. It will just lock up easier. If you can't lock up a 160 rotor there's something wrong with the brakes.

    I can lock it up when braking but the initial bite isn't half as good as the front brake...its the initial bite that I'd like to improve.
  • The Rookie
    The Rookie Posts: 27,812
    That's more likely a maintenance issue than to do with disc size.

    Is the lever travel excessive?
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • sete155
    sete155 Posts: 12
    just get some better quality brake pads...simples
  • The Rookie
    The Rookie Posts: 27,812
    No, as it depends what the actual issue is!
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • swod1
    swod1 Posts: 1,639
    you say the rear brake has new pads did you bed in the pads enough on the rear disc?

    A few hard stops without locking up the rear wheel as once you do it a few times you will feel the bite of the pads on the disc increase.
  • The Rookie
    The Rookie Posts: 27,812
    Was the disc cleaned of any contaminant that may have also killed off the previous pads.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • The front brake is always more effective than the rear one.
    If your pads are new, they'll take a bit to wear in.
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    If you drag brakes down hills they'll glaze before they bed in. Controlled braking is much better than constant dragging and much less likely to fry your pads
    Bigger rear discs are worth having for enduro and downhill riding where you might actually want to lock the rear occasionally to drift in to turns. Go too big and you'll just lock up all the time.
  • If it's any help, my front & rear are both 160, both the same disks & pads (both clean & adjusted) and the front is still "sharper". That's just basic physics though isn't it?

    I'm a novice as you can tell, but under braking (when descending ) isn't your weight predominantly put through bars and thus the front end as momentum pushes you forward?
  • FishFish
    FishFish Posts: 2,152
    Try swapping the front and rear pads - I've done that before when I could not be bothered bedding in the rear ones. The bedding in process is to sort out the surface of the pad to allow it to brake well rather than to adjust to the disk.
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  • poah
    poah Posts: 3,369
    I've got 203mm F&R and can't remember the last time I locked up on anything other than tarmac.
  • The Rookie
    The Rookie Posts: 27,812
    Eh? The bedding in is leaving a thin layer of disc pad material on the brake disc surface, braking is pad on deposited pad material.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.