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Adjusting my brakes on my Carrera Mountain Bike .... Please Help!

topshopper19topshopper19 Posts: 20
edited September 2018 in MTB workshop & tech
Hello everyone,

I have a Mountain Bike called a Carrerra Vengeance. Got it from Halfords just 6 months ago here:

https://www.halfords.com/cycling/bi...e ... -22-frames

There's been a few issues, one of which is the brakes. When pulling the brakes in my hand, the brake doesnt fully engage; and I always end up pressing down all the way to the handle bars without 100% braking power.

Please note: everything was perfectly fine when i first got the bike. But gradually, things have been going down hill.

When I press the brakes on the handlebars, it just feels too "soft". In other words, if I had to do an emergency stop, I don't think it would be fully effective.

I've watched videos like this [ https://www.youtube.com/watch?v=hg6s596PPRY ] but no luck. I've tried adjusting the "barrel adjusters" and tightened the brake cable (like in vid). It seems like it works temporarily, but then goes back "soft" again.

Can some of you give me advice about how to rectify this problem?

Thanks :mrgreen:

Posts

  • The RookieThe Rookie Posts: 27,747
    The page is a dead link as you've copied it from a truncated link from a forum post elsewhere.

    What make and model of brake caliper? V or disk?
  • cooldadcooldad Posts: 32,904
    Your link doesn't work.

    Assuming V brakes, sounds like you aren't tightening the cable up enough and it's slipping.

    Read Parktools link below for how to do anything.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • It looks like it has mechanical disk brakes.

    Sounds like your cable has stretched and maybe the barrel adjuster can't get enough tension in it.

    Also check your brake pads.They might be worn out.

    I'd suggest some entry level hydraulic brakes as they would be far better.

    EDIT:

    Something like this:

    https://www.ebay.co.uk/itm/Shimano-BR-B ... SwuMZZKBWl
    "Ride, crash, replace"
  • cooldadcooldad Posts: 32,904
    Cables don't stretch. They aren't rubber. Outers can compress a bit and settle, but that's it. And It's easy enough to adjust the clamp at the end of the cable to take up any slack. Whatever the brakes are.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • 02GF7402GF74 Posts: 1,294
    Of course steel cables stretch, whether the amount of stretch is measurable using a brake lever, I don't know but the outer cable can deform too....

    First thing to check is the cable at the calliper clamp and at the brake lever end. Over time strands in the cable break meaning there is less cable taking the force and thus easier to stretch...
  • cooldadcooldad Posts: 32,904
    Cables are pre stretched to remove any structural stress, and unless you are superman, you aren't going to get any elastic stretch by braking.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • 02GF7402GF74 Posts: 1,294
    Just come back from garage where I put a 1 m length of stainless steel cable in a vice and tried pulling it. Can't say I noticed any give..


    So although we know steel does stretch, it is doubtful that is the reason in this case due to the relatively small forces involved , either it is the outer or the brake lever and /or calliper that are deformaing.
  • 02GF74 wrote:
    Just come back from garage where I put a 1 m length of stainless steel cable in a vice and tried pulling it. Can't say I noticed any give..


    So although we know steel does stretch, it is doubtful that is the reason in this case due to the relatively small forces involved , either it is the outer or the brake lever and /or calliper that are deformaing.

    Steel cable does stretch. I often have to determine lifetime expectation of various cables ( and all sorts of other materials ). The determination is made using a tensometer which stretches the cable until it breaks, then looks at some parameters to try to determine how long it will last under use in application. It’s quite an eye opener, for the un initiated to see how a thin cable behaves when you stretch it. The OP’s issue is most likely due to the fact that mechanical disc brake systems don’t automatically adjust the distance from the pad to the disc, as the pad wears, like a hydraulic system does. So mechanical disc set ups do need a fair bit of manual adjustment, throughout the lifetime of the pads.
  • cooldadcooldad Posts: 32,904
    I take anything you say with the proverbial pinch of bullsh1t.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • david7mdavid7m Posts: 636
    Take it back to Halfords. At 6 months old it shouldn't be so pap. Tell them it's dangerous which sounds true. You shouldn't be paying unless you've damaged something.
    Dave
  • If they are mechanical disks i had exacly the same issue on my old carrera.

    As above, as the pads wear they cant compensate so the outboard pad has to push the disk onto the in board pad. This means you have to pull the brake lever further and further as the pads wear.

    If you look very closely you'll see that the brakes work by the cable pulling the outboard pad into the disk., then the pressure will slightly bend the disk into contact with the fixed inboard pad. If the pads are a bit worn then the pad thats operated by the cable has to push the pad a lot further to sandwich the disk between the two pads, hence your levers pulling all the way back to the bars.

    If you do a lot of riding you'll absolutely have to adjust them more than every 6 months.

    Get a long allen key and put it through the wheel and manually wind the inboard pad toward the disk until it just fouls the disk when you spin the wheel, then wind it back a tiny bit to stop it rubbing.

    And obviously ensure theres still some pad left on the pads!

    Thats probably your issue. It wouldn't hurt to also check there is no slack in the cable, there should be just enough cable tension to keep the ouside pad as close as possible to the disk without it touching.

    Basically with mecanical disk brakes you do need to adjust them on a semi regular basis, that's just how they are, especialy with organic brake pads as they wear quicker. I prefer organic pads as they don't sqeaal as much and i prefer the feel, but they do wear quicker than semi metallic pads in dirty conditions, and with mechanically operated brakes the wear is more pronounced by having to adjust them more often.

    I've upgraded to hydraulic brakes since. Mechanical brakes are just as good when perfeclty adjusted, but i got sick of having to mess about with them every month or two to keep them biting well.
  • larkimlarkim Posts: 2,287
    Lots of good advice here on how to sort out what you have. It is definitely possible to have mechanical discs working well, but my personal experience as a cack-handed amateur is that if you upgrade to cheap shimano hydraulics (as linked earlier) you'll get yourself a noticeable upgrade with significantly less hassle. Just fit and forget.
    2015 Canyon Nerve AL 6.0 (son #1's)
    2011 Specialized Hardrock Sport Disc (son #3s)
    2013 Decathlon Triban 3 (red) (mine)
    2019 Hoy Bonaly 26" Disc (son #2s)
    2018 Voodoo Bizango (mine)
    2018 Voodoo Maji (wife's)
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