Speed shimmy/wobble

Ashley_R
Ashley_R Posts: 408
edited January 2008 in Road beginners
My mate's bike has developed a disturbing speed wobble at about 25mph which despite going back the LBS twice where he bought it from hasn't showed any noticeable defects

The bike is a Trek 1500 and about a year old, he seems to think it did it from new but seems a whole lot worse now, to the point where he doesn't feel safe riding it

The LBS have checked the headset, wheels and the frame alignment, all perfectly fine. He's tried all the things like griping the top tube when it happens and standing out the saddle, all to no avail. The only thing he hasn't tried that I've read is taking your hands off the bars, he's a bit reluctant to do this for some strange reason! :shock:

He's tried a different front wheel, same results, I've suggested trying a different stem, seatpost or something, just to try and alter the resonance point or whatever it is causing it, anyone any other theorms or suggestions?
You can lead an elephant to water but a pencil must be lead

Comments

  • Anonymous
    Anonymous Posts: 79,667
    Is it a mechanical wobble or just a bit bumpy.
    I had a similar problem on my road bike whereby part of the sidewall on the tyre had perished (and it was supposed to be brand new!). Check these. If this is it and its a set of vittorias let me know. I cant do much about it but its something to keep in mind in future
  • heavymental
    heavymental Posts: 2,076
    I had this problem after raising up the stem on my old bike (Alu with straight bladed alloy forks) For some reason it didn't seem to like that change to the stem. I stuck it back down and it did fix it to some extent but was still a bit present. But worse than that it was a possibility lodged in my head that it might happen again. Luckily, I happened accross a new pair of carbon forks and stuck on a new stem so the whole system was changed. It worked a treat and after a few months by confidence on the descents was renewed.

    Check everything is nice and tight then make some adjustments if it doesn't go away. Also, do a search here for wobble/shimmy. There have been lots of threads in the past with lots of tips.