Rear break fishtailing?

Moonbiker
Moonbiker Posts: 1,706
edited December 2013 in Workshop
Hi have theese pads

http://www.wiggle.co.uk/clarks-road-cal ... e-inserts/

On some old tektro calipers when rear breaking the back wheel skids towards kerb side.

Worth trying some different pads or is it a caliper problem? Gone through the parktool book can't work out what is causing it?

Comments

  • rolf_f
    rolf_f Posts: 16,015
    Stop braking on the back wheel.... ;)
    Faster than a tent.......
  • matt-h
    matt-h Posts: 847
    Try applying the front brake just before the rear.
    The front wheel can take a lot more before locking up due to weight transfer.
    i only really use the rear on slippery roads or when turning

    Matt
    Scott Foil Di2 viewtopic.php?f=40044&t=13020685&p=19496365#p19496365
    Genesis Volare 853 viewtopic.php?f=40044&t=13020702&p=19589281#p19589281
  • napoleond
    napoleond Posts: 5,992
    When braking, slowly apply the rear until you feel it's having an effect, then start adding front pressure. Keep your weight over the back wheel.
    Insta: ATEnduranceCoaching
    ABCC Cycling Coach
  • matt-h
    matt-h Posts: 847
    sorry Nap, i disagree.
    Coming from motorcycles and bicycles, good practice of use of the front brake will have far more control and power than the rear.
    If its really slippy or my entry speed into a corner is to high, i sometimes use more rear.
    The front in this instance can cause the bike to 'stand up'

    Matt
    Scott Foil Di2 viewtopic.php?f=40044&t=13020685&p=19496365#p19496365
    Genesis Volare 853 viewtopic.php?f=40044&t=13020702&p=19589281#p19589281
  • kajjal
    kajjal Posts: 3,380
    Does it do this when you are on a flat, straight , dry road ?
  • Bozman
    Bozman Posts: 2,518
    80% front brake in the dry but at this time of year when the roads are greasy I'll swap that around, brake earlier and feather the brakes.
    If you grab a handful of front brake on a greasy road you can quite easily end up on your arse,
  • MichaelW
    MichaelW Posts: 2,164
    I get fishtailing a bit on my disc-equipped bike on steep hills with steep camber. Its not something I notice with rim brakes. I just release the rear brake and use the front.
  • andrew_s
    andrew_s Posts: 2,511
    Fishtailing means the back wheel is locking up. Whilst the wheel is rolling, you have normal traction, but once it starts to skid it will go sideways as easily as forwards, and there's the front wheel stopping it going forwards. Normally it skids down the road camber. Reduce back brake pressure and it will start rolling and come back into line.

    It's nothing to do with the brake blocks, only how fast you are slowing down and how hard you are braking on the back wheel. The faster you are slowing down, the less back brake pressure is needed to lock the back wheel. At the limit, any back brake pressure at all locks the back wheel, and over the limit the back wheel comes off the ground and you land on your face (unless you ease off on the front brake pretty quickly).
  • Moonbiker
    Moonbiker Posts: 1,706
    Does it do this when you are on a flat, straight , dry road ?

    Yeah it does.

    Tried breaking the same way (with just the rear) on a different road bike as an experiment & that bike & didn't veer/pull to one side like mine. :roll:

    Will have another mess around with it tommorow see if can fix it etc.
  • marcusjb
    marcusjb Posts: 2,412
    So, on your bike, you brake and lock the rear wheel and it always fishtails in a certain direction.

    You try another bike and it stays straight even as you lock the wheel?

    Assuming those frame have similar geometry and weight distribution.

    Bent or poorly tracked frame is a possibility.
    Stuff about riding a bike a long way
  • Moonbiker
    Moonbiker Posts: 1,706
    So, on your bike, you brake and lock the rear wheel and it always fishtails in a certain direction.

    You try another bike and it stays straight even as you lock the wheel?

    Correct

    When its its fishtailling the rear wheel isn't fully locked the wheel is still rotating but with pressure on the rim from the brake pads.


    Tried a different rear wheel on my bike and it still veering to the side.

    I have checked the frame & I can't see any cracks/damage bent rear stays. Could the frame bend slightly without showing any external signs, its a steel frame - cromoly 4130

    Only thing now left to swap out is the rear break caliper.
  • andrew_s
    andrew_s Posts: 2,511
    Cracked dropout, where it joins the chainstay?
    Try taking the wheel out and pulling backwards on the bottom end of the seatstay, & check for movement.

    I can't see that the brake would make any difference, but one end of the axle moving away from the BB does steer the back of the bike sideways (happened to me).
  • marcusjb
    marcusjb Posts: 2,412
    I really don't think changing your brakes or anything like that will help - it does really sound like an issue with the frame. Andrew_s's suggestion of a cracked dropout is a sensible one for sure.

    Really look over the rear end frame in detail - check the other end of the seat-stays as well as a common point of failure is the seat-stay to bottom bracket joint.
    Stuff about riding a bike a long way
  • Balaclavas
    Balaclavas Posts: 61
    Is this actually an issue? All of my bikes fishtail one way or the other if I lock the rear wheel, depends which way im leaning or which foot is down. If the bike rides in a straight line quite happilly without the wheel locked just try not to lock the wheel, it doesn't slow you down as quickly as an un-locked wheel, it's just a good way to wear down your tyres. Even worse offroad where it litters the trail with braking holes.
  • cougie
    cougie Posts: 22,512
    I'd rather it went toward the kerb than swung the other way. But how often are you locking your back wheel up ? I cant remember the last time I needed to do that.

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