Viewing 28 posts - 1 through 28 (of 28 total)
  • New wheels…… Speed wobble
  • paulmgreen
    Free Member

    I’ve fitted new wheels today on my road bike ….. Went out for a ride …. Came to a long downhill section…. Hit 33mph and suddenly got a massive speed wobble….. Very nearly uncontrollable.!?

    I can’t figure why this should happen? The new wheels are perfectly straight as they should be….. Spin easily…. Tyres are mounted straight … No wobble on bearings …..

    How can this be ?

    CaptainFlashheart
    Free Member

    Brexit.

    (Not really, obviously!)

    Could be that they are out of true on the vertical (assuming you hadn’t checked that), but then it could just have been the wind.

    paulmgreen
    Free Member

    It was just a slight tail wind …… The wobble was sudden and violent !

    I’ve taken both wheels out and checked tyres are both on true ….. So if they were loose or not in line then hopefully cured in process. .

    tillydog
    Free Member

    Are the spokes tight?

    cynic-al
    Free Member

    Did you have your weight off the bars?

    paulmgreen
    Free Member

    Spokes seem OK…… Riding position no different to normal…. It’s a hill I ride down regularly

    Might try isolating which wheel is causing by trying route again with old front wheel back in ….

    slowster
    Free Member

    I thought speed wobble was primarily determined by the bike’s geometry, the distribution of weight on the bike (rider and any luggage), and reaching the speed necessary for the oscillation to occur.

    I’m surprised that wheels would cause it, unless the geometry and weight distribution were such that the bike was already more prone to speed wobble, and the difference (maybe weight?) between the old and new wheels has been the tiping point factor which has resulted in wobble now occurring.

    doodlebug
    Free Member

    Tyres to wide for your new rim, it happened to me 🙄

    paulmgreen
    Free Member

    really?? they are 25mm tyres …. not huge ??
    what size tyres did you have ?

    frogstomp
    Full Member

    Any play in the bearings / adjusted correctly?

    trail_rat
    Free Member

    Tyres to wide for your new rim, it happened to me

    Nonsense.

    Your tires were not very uniformly weighted if new tires helped.

    Ive seen this caused by wheels that have heavy spots – be it tyres or wheels or otherwise.

    Spin wheel slowly if it’s out of balance it will always stop with the same spot at the bottom.

    Also seen some bikes where the frames not straight causing it. But if y was fine before wheel change then it’s wheel related I’ll bet.

    stumpy01
    Full Member

    Some kind of aero effect? Have they got a vastly different profile to the previous wheels? Deeper rims? Bladed spokes??

    Sounds scary!

    amedias
    Free Member

    Speed wobble is a result of an input force setting up a vibration which then resonates.

    The force/vibration can come from literally anywhere, hitting a pebble, the particular road surface, a slight variance in wheel true/weighting, the wind, anything.The particular resonance will be affected by things too, geometry, speed, weight distribution, flex/stiffness etc. Some factors will be very minor influences and easily overshadowed by others so it can be very difficult to both predict and locate the cause of wobble, changing one variable could completely eliminate it or magnify it.

    I’ve only ever had one bike prone to it, and it was only prone to it with one particular wheel and tyre combo and at a very specific speed, changing either the tyre OR wheel got rid of it for me.

    Basically it’s time to get experimenting and process of elimination, however… Check your headset for correct adjustment as that’s an often overlooked cause.

    paulmgreen
    Free Member

    yes … it was certainly scary ! The bike is normally rock solid….. and I went down the same hill a week earler … only change is the wheels…… I shall go back over the suggestions made and doublecheck everything through ….

    thanks for the input fellas

    epicyclo
    Full Member

    First thought was could the wheel be straight but slightly offset. Do a trial fit in the fork the other way round to see if the rims are different distances from the fork legs.

    Other thought was, were you carrying a load on one occasion, eg back pack or panniers?

    eskay
    Full Member

    Were you cold? Sometimes a cold rider shivering downhill can cause.

    I have had it a few times and it is truly terrifying, you have no control of the bike. Luckily each time I have had it the bike has veered to the left.

    retro83
    Free Member

    I used to be able to stop mine wobbling by pressing my knee against the top tube.

    It went away on its own at some point so I think it must have been a bad tyre in my case (though it looked fine)

    jameso
    Full Member

    New wheels weigh much different at the rim/tyre?

    Wheel weight will influence shimmy as part of the system that’s resonating, as above it’s mainly about weight distribution, frame flex and steering geometry – wheel weight can come into it as a heavier wheel will have a bit more resistance to the shimmy ie it lowers the resonant frequency enough for it not to be an issue / occur.

    mcj78
    Free Member

    Only time i’ve ever had it, was due to not effectively tightening the cheap qr skewers on a bike – they had a really particular “bite” point & anything else meant they ended up too loose (which was obvious) or too tight & the lever wouldn’t completely close (so, again ended up too loose – felt tight until you cycled down the street wondering why your steering felt weird).

    mrjmt
    Free Member

    Had it on a PX Pro Carbon. Because they’re flexi floppy rubbish.

    trail_rat
    Free Member

    Mrjmt.

    Funnily enough that’s the bike we couldn’t solve the issue on. It was utterly horrendous bike bordering on unusable.

    If you didn’t know it was coming it would havr you off the bike in a heart beat. As above if you clamp knees and increase the mass of frame it calmed down.

    Transpired the fork ends and frame ends were a good 1/4-3/8s of an inch out of line with each other

    Planet x and intense have one thing in common 🙂

    paulmgreen
    Free Member

    Update …. So I’ve removed tyres and refitted ,…. Made sure everything is tight …. Took it steady down same hill … Tentatively built up to 35 mph without the death wobble…. So fingers crossed ok ….. Will try again next week and see how it goes

    tjagain
    Full Member

    check the wheel balance. ie where it stops when it spins

    djflexure
    Full Member

    How heavy are you?
    How many spokes on the new wheels?
    I had similar experience. Upped spoke count and wobble went away

    cynic-al
    Free Member

    Upped spoke count and wobble went away

    All other factors remained unchanged?

    djflexure
    Full Member

    Just changed the wheels and could go as fast as I wanted
    32 f&r – had been on low spoke count wheels
    I’m about 90kg

    trail_rat
    Free Member

    Ah so you didn’t just drill some new holes in the hub and rim. So could have been a lump of weight in the rim perhaps

    cynic-al
    Free Member

    djflexure – Member
    Just changed the wheels and could go as fast as I wanted

    So could have been many factors

Viewing 28 posts - 1 through 28 (of 28 total)

The topic ‘New wheels…… Speed wobble’ is closed to new replies.