Bump on new Tubs!!!

paulieb2006 Posts: 318
edited April 2012 in Workshop
Just had a new set of tubs put onto my carbon 50mm wheels 2 weeks ago! noticed a small bump in the tyre just where the valve is! On both of them! Its like as if there is something under the tub between it and the Rim. What could this be. Showed it to the owner of the bike shop on Tuesday evening but he said he couldnt really see anything! Has anybody got any ideas? Its Conti Sprinter Tubs on Fuerte Bici wheels.


  • GiantMike
    GiantMike Posts: 3,139
    Maybe where the valve isn't sitting on the rim correctly?

  • sturmey
    sturmey Posts: 964
    It's a common problem. Some makes of tub are worse than others. It happens because the base tape round the valve bulges and doesn't sit flush in the valve hole in the rim.
    Solutions are :
    1.File away the valve hole slightly to allow the tyre to sit better.
    2. Trim the basetape very slightly round the valve.
    3.Don't spare the glue around the valve.
    4. Make sure when mounting the tyre for its final fit you stretch the tyre fully as you work away from the valve.
    5. As soon as it's mounted partially inflate the tyre and slowly roll the wheel across the garage floor with your weight bearing down on it to get good adhesion.

    You still might see the tyre sitting slightly proud at the valve area which may be a result of being too cautious at stage 1 and 2 but it's your call and too much trimming/filing could be a mistake.