Tube/valve question - presta

Discussion in 'Cycling Equipment' started by lspeedguy, Sep 24, 2018.

  1. lspeedguy

    lspeedguy New Member

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    I know that the valve on a tubeless tire has a removable core to permit the injection of sealant - a few months ago I had some upgrades done by my local shop and asked them to install tubes rather than go tubeless - a couple days ago I was removing the plastic valve cap and the core of the valve came out with it , immediately flattening the tire .

    Question : To some tubes come with a valve that has a removable core or do I still have a tubeless setup ? wanted to ask here first before I go back to the shop because I was charged for 2 tubes .
     
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  2. dabac

    dabac Well-Known Member

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    Some tubes do come with removeable cores while others do not.
    Those who don't can be a little cheaper.
    With removeable cores you can use sealant in the tube if you wish.
    It's also possible to replace the core should that little knurled nut come off, the core jam or some other mechanical issue occur with it.
    At the risk of the core coming off inadvertently of course.
    You'll have to unseat the tire to find out which it is.
     
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  3. lspeedguy

    lspeedguy New Member

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    Thanks Dabac , a few hours after I posted this question the lightbulb went on and I remembered that the shop did say that the valves on some tubes come with removable cores in the event you want to inject a sealant like Slime, etc. - with hindsight I think I tightened the plastic valve cap too tight and when I unscrewed it the core came with it - live and learn :) - thanks again for the reply !!
     
  4. Chuckabutty

    Chuckabutty Active Member

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    It seems that the bike shop somehow jammed the dust cap onto the valve. I have Prestas on my fat bike and never had a problem with the dust cap removing the core. The only way I can see the cap getting jammed onto the valve core is if the core wasn't screwed in all the way.

    Schrader valves have a removable core and so does the Presta, even though some people say it can't be removed. A circular multi-size spoke wrench will remove a Presta core, but getting Slime into it could be difficult. I was advised by my former LBS not to Slime a tube because it can clog up the valve.
     
  5. dabac

    dabac Well-Known Member

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    SOME Presta cores are removeable, some aren't. Those that are have tool flats ground through the valve cap threads.

    DOn't know about "Slime", but the sealants generally used for tubeless setups can be injected through a Presta stem with core removed easily.

    Win some, lose some.
    Clogging a valve CAN happen. Not much of a problem with removeable cores as long as you're carrying a spare. Running a tube/tire with sealant gives you a good chance of flats sealing themselves, maybe even fast enough that you don't even have to top up pressure before riding on.
    Some may think that benefit is worth the risk of a clogged valve.
     
  6. Froze

    Froze Well-Known Member

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    In low pressure tires, under 65 PSI Slime works pretty good, but it fail miserably at higher pressure. Of course Slime can clog a valve if the valve isn't in the right position; see:

    View: https://www.youtube.com/watch?v=QhubsdWCpNw
    That video shows where the valve is suppose to be when you put the Slime in, the one thing they didn't show was that after you have aired the tube up you should slowly spin the wheel at least a hundred times to get the stuff to spread all over the tire.
     
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