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Fitting inner tube - what to do with the nut?

maxpppmaxppp Posts: 39
edited September 2009 in Road beginners
Hi guys,

Got a puncture, went to replace the inner tube, opened the box with the new inner tube (a specialized presta 700x28-38 jobbie) and there was a screw on the valve.

Is this necessary? If so what side of the rim does it belong (i.e. on the outside next to the cap or the inside next to the rubber/valve).

Thanks,

James.

Edit: I meant there was a nut on the valve, not a screw. I have now fitted it without.

Posts

  • Bin it. And the dustcap.
  • You mean a screw-on nut type thing? I keep it on so I have plenty of valve poking out for my pump to connect onto.
  • VelonutterVelonutter Posts: 4,749 Lives Here
    Bin it because when tightened it can cause your tube to pull at high speed and create a puncture.

    When I used to race super motards we binned them for exactly the same reason.
  • Madprof wrote:
    You mean a screw-on nut type thing? I keep it on so I have plenty of valve poking out for my pump to connect onto.
    You don't really need that much valve though. If you force the pump head on then it can make it quite hard to pump up your tyres. Having about a centimetre of the valve in the pump head is perfectly fine.
  • whyamiherewhyamihere Posts: 7,474
    Slow-N-Old wrote:
    Bin it because when tightened it can cause your tube to pull at high speed and create a puncture.

    When I used to race super motards we binned them for exactly the same reason.
    You're not supposed to tighten them that much...
  • It's got nothing to do with how tight they are on a motorcycle - the tyre creeps on the rim and takes the tube with it thus tearing the valve out. Normal practice on comp machinery is to dispense with the locknut and elongate the hole a bit to allow more movement before disaster occurs. It can then be spotted and the tyre moved back round the rim.
  • VelonutterVelonutter Posts: 4,749 Lives Here
    It's got nothing to do with how tight they are on a motorcycle - the tyre creeps on the rim and takes the tube with it thus tearing the valve out. Normal practice on comp machinery is to dispense with the locknut and elongate the hole a bit to allow more movement before disaster occurs. It can then be spotted and the tyre moved back round the rim.

    That is what I meant in a roundabout way, same conclusion..a puncture.
  • John.TJohn.T Posts: 3,698
    Slow-N-Old. You must have some power to get a bike tyre to creep. I can understand 100+ horse power on a motorcycle but it will not move with our meagre power and 100 psi in the tyre. I leave them on. It stops that annoying rattle of the valve in the rim, especially with deeper section ones. Just give it a slight nip after blowing the tyre up.
  • VelonutterVelonutter Posts: 4,749 Lives Here
    John.T wrote:
    Slow-N-Old. You must have some power to get a bike tyre to creep. I can understand 100+ horse power on a motorcycle but it will not move with our meagre power and 100 psi in the tyre. I leave them on. It stops that annoying rattle of the valve in the rim, especially with deeper section ones. Just give it a slight nip after blowing the tyre up.

    Nope not me mate, I'm slow and Old, I just mention that when I used to race both Bikes and Motor bikes that that was the reason why everyone recommended not to use a collar.

    I wish I did have the power, it would make it easier on those damn hills :shock: :lol:
  • I tend to leave mine on, I find that when i have a P*&(&^%XX!! using the nut to take up the slack when the tube inflates reduces the stress on the area around the valve as im pumping the thing up...

    re-punctured by damaging the valve once years ago in the middle of nowhere.....its stayed with me since!

    this only relates to hand pump though and has no bearing on track pump due to lack of lateral movement of pump head.
    http://www.northcheshireclarion.co.uk/

    Great club in and around the Warrington area.
  • geoff_ssgeoff_ss Posts: 1,234
    I usually leave the nut on but quite loose because it helps to push against when pumping up a totally flat tyre with a hand pump. Not too worried about the valve cap except I use them on spare tubes to help prevent the sharp valve from damaging the rubber.

    I also left the valve nuts off on my trials motor cycles for the reasons stated above by 'Slow and old' (me too!). But riding a motorcycle with 4 to 6 psi in the tyre is rather different from a pedal cycle running at 100psi. I can't see there being in any tyre creep there. In any case we used to fix the tyres to the rims with special security bolts - just one on a solo but up to three on a sidecar outfit. Made it a censored to change the tyre. I think trials car drivers screw self tapping screws into the tyre bead through the rim to do a similar job.

    Geoff
    Old cyclists never die; they just fit smaller chainrings ... and pedal faster
  • ProssPross Posts: 28,325
    To answer the original question - you don't necessarily need it at all but if you use it it goes on the outside of the rim. As for the dustcap, as said bin it!
  • bikerZAbikerZA Posts: 314
    Dustcap has no value, but the nut is useful when you're pumping the tyre up to keep the valve nice and exposed. Take it off as soon as the tyre is inflated, as it's only going to get in the way and slow you down the next time you have to repair a puncture.
  • sheffsimonsheffsimon Posts: 1,282
    Dustcap stops presta valve nut corroding so you cant unscrew it to pump your tyre up - I say fit it.

    I always fit valve stem nut also, never had a problem with valve being ripped off.
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