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Wheel Balancing

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  • 27-09-2014 10:36am
    #1
    iamtony
    Registered Users Posts: 3,801 ✭✭✭


    I'm just wondering if this is a thing on bikes?
    I'm not talking about straightening a bent or buckled wheel. I Presume imbalances do occur with tyres
    The reason I ask is if I lift my bike a bit and spin the wheel there is a slight pull up and down as if one side is heavier than the other.
    If it's not done why not?


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    #2
    browsing
    Registered Users Posts: 186 ✭✭browsing


    iamtony wrote: »
    I'm just wondering if this is a thing on bikes?
    I'm not talking about straightening a bent or buckled wheel. I Presume imbalances do occur with tyres
    The reason I ask is if I lift my bike a bit and spin the wheel there is a slight pull up and down as if one side is heavier than the other.
    If it's not done why not?
    I think your wheel may be out of true which is causing that problem. if you rotate it and look at a fixed point like the brake blocks you might notice. usually the problem with out of balance car wheels is that they hit a resonant frequency and the oscillations become quite large which is usually around 60mph which is *usually* much faster than what a bicycle would travel at. the larger wheels on a bicycle would also cause
    them to rotate more slowly for a given speed, most likely significantly increasing that resonant speed so its not relevant for bikes I'd have thought. that said, top end wheels sometimes have some extra material directly across from the valve to balance out the weight if the valve


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    #3
    Lumen
    Registered Users Posts: 31,008 ✭✭✭✭Lumen


    browsing wrote: »
    I think your wheel may be out of true which is causing that problem. if you rotate it and look at a fixed point like the brake blocks you might notice. usually the problem with out of balance car wheels is that they hit a resonant frequency and the oscillations become quite large which is usually around 60mph which is *usually* much faster than what a bicycle would travel at.
    In a car with an unbalanced wheel, the resonance doesn't happen in the wheel system itself but in system of suspended mass (car) the wheel is the attached to. Road bikes don't have suspension so there's not quite the same problem, although I guess it's possible that the dreaded speed wobble might come from a vertically out of true wheel or a badly fitted inner tube.


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    #4
    iamtony
    Registered Users Posts: 3,801 ✭✭✭iamtony


    Yes good points I didn't realise a wheel could be vertically out of true. It does seem to be straight horizontally and its fine while cycling, it was just a thought I had while playing with the bike and thought id ask.
    Counter balancing the tyre valve makes sense in my mind alright.


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    #5
    crosstownk
    Registered Users Posts: 12,863 ✭✭✭✭crosstownk


    Spin out your 50/11 or 53/11 on a stand and imbalance will be prevalent.

    Some decent discussion here.
    Untitled Image




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    #6
    iamtony
    Registered Users Posts: 3,801 ✭✭✭iamtony


    crosstownk wrote: »
    Spin out your 50/11 or 53/11 on a stand and imbalance will be prevalent.

    Some decent discussion here.
    Interesting read. It might make sense that I can feel the imbalance as I have carbon wheels which don't have a seem so the presta valve can cause an imbalance.
    I used to race Karts and would counterbalance the wheels and it was generally opposite the tyre valve that needed the weight which makes me think that the tyres aren't as much of an issue as the tyre valve.
    Seems like some think it is an issue and some don't on bikes.


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