Wobbles down hill

Bigphillyb
Bigphillyb Posts: 21
edited April 2015 in Road general
Hi guys,

The back of the bike seems to wobble when I go down hill at around 20mph or above.
Any ideas ?

Cheers
P

Comments

  • sungod
    sungod Posts: 16,612
    speed wobble usually is the front, if it's the rear then to be going on with i'd check...

    is the wheel seated fully in the dropouts and the qr tight

    tyre corectly seated

    is the wheel out of true

    any loose spokes

    any bearing play

    is the axle broken
    my bike - faster than god's and twice as shiny
  • DavidJB
    DavidJB Posts: 2,019
    You also wouldn't get 'speed wobble' at 20mph ... not that I've ever had it.......
  • marcusjb
    marcusjb Posts: 2,412
    (Speed wobbles can occur at lowish speeds despite the name). It is odd for it to manifest at the rear though. Two major speed wobbles in my life make it an experience I really never want to repeat though!

    Sungod's list is a good start.

    Check the frame - especially around chain stay and bottom bracket etc (certainly a common failure spot in steel frames! Less likely on carbon frames, but if it has a developing crack there, it could cause the issue).

    It is really a question of grabbing everything and giving it a wobble to see if there is movement. Saddle, seatpost, wheels, rear triangle.
    Stuff about riding a bike a long way
  • Wardster00
    Wardster00 Posts: 143
    I had this and it turned out that it was the cones on the wheel were not tight enough giving quite a bit of play in the wheel.

    Obviously this wont be the cause if you have sealed bearings in your wheels.
  • JayKosta
    JayKosta Posts: 635
    Check the air pressure. And try will a little more pressure unless you are already at the maximum.

    Also, if there are reflectors on the wheels, they might be causing a balance problem.
    Generally the reflectors are placed opposite side from the valve stem. Perhaps remove them, or try smaller ones.

    Jay Kosta
    Endwell NY USA

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