Home Chat General Chat

Bike Wobble: Today i thought i was a gonna!

During a fast decent this morning i thought i was going to die! The bike started to wobble and i thought the front wheel was going to come clean off! I must have been pushing 65-70kph at the time.....i really thought i was in trouble.

Anyway, hit the brakes (in hindsight this is probably not such a good idea) and came to a stop. I checked the bike for loose bits but nothing! The bike had just started to wobble because it felt like it.

I don't want that to happen ever again, it was far from pleasant! So, can you lovely people please tell me a) Why? and b) What i can do to prevent it?

Thanks in advance

A shaken up GaryRoberts!


  • Hey Gary, I'm sure there are much more knowledgeable people here and they'll be along with their advice in a minute but in the meantime. I think something similar happens with motorbikes where the front wheel becomes slightly unweighted and unstable resulting in the bars oscillating wildly from side to side, called a tank slapper.

    Perhaps at your speed the front wheel did the same. Maybe keeping a little more weight over the front wheel with your position on the bike would help. Glad to hear that you're ok, though.

    If I've just offered advice that will actually make things worse I await to be corrected by the masses
  • Swizzlenap, You're quite right about tank slappers on motorbikes; the solution is to have a steering damper fitted (see below), not sure why this happened on a pedal biike though, or whether there is such a thing as a cycle steering damper.
  • BlinkybazBlinkybaz Posts: 1,144
    Mr Roberts

    That sounds kind ball slappingly scary!
    Dont let it get into your mind that it will happen again. Get on the beast and nail that descent aghain soome1
  • stabilisers?
  • huwdhuwd Posts: 228
    Maybe wheel balance? If you imagine when a car balance is out there is often a small speed range where it is worst, and dropping below or pushing past it see the effects reduced. Have you checked the tyre condition and that the wheels run true (checking spacing on the brake blocks whilst spinning the wheel to check for uniform spacing
    Sounds proper scary!
  • Thanks guys.......i'll check the spokes out (didn't check them yesterday).......
  • Did your bibs need a wash.


    I can imagine its very frightening.
  • I had this and found it was due to low tyre pressure. Pump 'em up high and try the same hill again - see if it works.
  • Had this happen myself.
    Interestingly at the same speed.
    Nice sensation isn't it!

    Try this: http://www.bikeradar.com/fitness/article/qa-speed-wobble-14776
  • http://www.youtube.com/watch?v=xODNzyUbIHo

    This crazy fool makes it happen on purpose. Looks like it can stopped by standing out of the saddle though as this changes the resonant frequency of the bike.
  • BopomofoBopomofo Posts: 980
    Problems with resonance can be solved by changing the mass of whatever is wobbling. In the case of front wheel wobbles that includes wheel, forks, bars and _your arms_

    So, relaxing your grip on the bars usually sorts it out. Takes your arm mass out of the system. Also, a loose grip then has a damping effect.

    Hitting a bump on my Dolan at about 55kph or so can sometimes set her off. Relaxing the death grip has stopped the wobbles (and ensuing brown shorts) every time.
  • ZacniciZacnici Posts: 1,385
    That happened on my first tri on a knobbly tired fitted MTB. Bikers do indeded call it tank slappping and there is a steering damper available for MTB's (Hopey) although I know someone who doesn't like light steering who put a neoprene insert in his steering tube which he swears gives more stablity and stops the steering flying off at the slightest knock. It does indeed feel more stable and steering is still light but not feather light.

    Scarey and basically not a lot you can do other than grit your teeth and ride it out as braking too vigorously can cause a 'steeping off'.
  • Paul123Paul123 Posts: 13
    dangermouse wrote:

    Try this: http://www.bikeradar.com/fitness/article/qa-speed-wobble-14776
    Good read thanks for that one.
Sign In or Register to comment.