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  1. #1
    mtbr member
    Join Date
    Oct 2012

    Tubeless conversion question- leaking at Presta valve

    I'm converting my 2012 Stumpjumper FSR Elite to tubeless. Bike has Roval Control Trail wheels (supposedly tubeless ready) and 2Bliss tires.

    So just to test things out I inflated everything without sealant. Everything seems fine except there is some air leaking around the Presta valve area. I'm using the Stands valves and I cranked the nut down pretty tight with some needle nose pliers.

    Is this something that the sealant will seal? I wanted to make sure before I dump Stans in there and get everything messy.


  2. #2
    fRIDEday makes me happy!
    Reputation: FullBladdy's Avatar
    Join Date
    Aug 2011
    I have converted roval rims with stans tape and valve stems without issue but I did use sealant at initial install as thorn protection is key. I say go ahead and inject some stans which will most likely take care of the issue, make sure to get all the fluid down by the valve and shake it after inflating to coat the area.

    If the stans does not gunk up the leak it may be a good idea to look at the taping job and hole created for the valve. Good luck!

  3. #3
    Reputation: RustyIron's Avatar
    Join Date
    Apr 2008
    I've had a little bit of leakage around presta valves. Tightening the nut helps, but the sealant takes care of it right away.

  4. #4
    mtbr member
    Reputation: ewarnerusa's Avatar
    Join Date
    Jun 2004
    My Rovals also initially leaked a bit from around the valve stem during the first inflation. One shake of the sealant and things sealed right up. But I was using the included stock tubeless valve stems vs Stans stems. I suppose it is possible that those stems don't interface ideally with the internal rim bed.
    I think cranking down on the valve stem nut with pliers is not recommended in any case though. Way more force than is necessary and could damage the rubber seal on the valve stem, tubeless tape/rim strip, and/or rim.

  5. #5
    mtbr member
    Join Date
    Sep 2010
    Don't crank down too much on the valve nut as it can and will fail. I always put a little 100% silicone around the base of the stem before putting it into the rim to avoid these kinds of leaks. Also be sure that the leak is just around the stem. Sometimes the rim tape will leak and you'll have air leaking inside the rim and coming out around the stem and nipples.

  6. #6
    mtbr member
    Reputation: ColinL's Avatar
    Join Date
    Feb 2012
    Try the Specialized/Roval tubeless valve instead. It probably has a different shape because a UST / UST-like rim bed is not shaped like a normal clincher rim.

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