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  1. #16
    Join Date
    Jun 2010
    Posts
    6,465

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    I just finished watching the first one, Dubz. You've no idea how perfect that was to me. Thank you!
    So long as the wheels are still turning, life is good.

    Battswebb

    Pinarello Quattro~CAADX~ Zurich Lemond
    Specialized Romin Saddles

    Surly Krampus!

  2. #17
    Join Date
    Jan 2015
    Posts
    32
    My pleasure, Muirenn!

  3. #18
    Join Date
    Sep 2007
    Location
    Uncanny Valley
    Posts
    14,645
    I'm wondering if you have the pump head set straight. It's possible - actually kind of easy - to get the pump head just slightly crosswise on a Presta (a not o) valve, so what happens when you press the plunger is that pressure just builds up inside the hose but doesn't go into the tube because the valve stem isn't depressed.

    Without having watched all the videos and I'm not sure what's already been explained here - a Presta valve has no spring. The valve is held closed simply by the air pressure inside the tube, and the lock nut on the valve stem is just for extra security when going over bumps. So the corollary to that is that it needs air pressure from the outside to open the valve and fill the tube. But if the valve stem is jammed up against the gasket, which can happen if it isn't exactly straight, then the valve will never open. That's why it can be so very hard to pump a completely empty tube - without any air in the tube, the valve stem just wobbles around and is very hard to keep aligned.

    I personally find it easiest to get the pump head on and straight at 12:00. Some do better at 6:00 - to me, I get too much pull from the hose in that position and I have to be bending down too far to steady the head effectively, but it's all what works for you. You'll want to hold the pump head straight - heel of your hand on the tire, fingers on the pump head - while you use your other hand on the plunger until you can feel air going into the tube.

    Difficulty in getting the pump head on exactly straight can be a sign of wear in the gasket, too. Again, I didn't watch your videos - it sounds like your pump head has separate attachments for Schraeder and Presta? Most pumps use a single head, and in that case if it's been used much on Schraeder valves, it can wear pretty quickly to the point where it's no use on Presta valves. But even if it's only ever been used on Presta valves, it will wear. Every couple of years is a typical replacement interval. Rebuild kits are cheap and your LBS should have them.

    As far as tire pressure - recommendations based on road conditions and rider weight are for the road. On the trainer, I would definitely inflate the tires to max recommended pressure to minimize tread wear and heat buildup.
    Speed comes from what you put behind you. - Judi Ketteler

  4. #19
    Join Date
    Jan 2015
    Posts
    32
    @Oakleaf - Thanks for your advice.

    Everyone else: I managed to resolve this issue after going to my LBS and getting them to check my pump and training tire.

    Here's a video from Terry Bicycles which is really useful.

    https://www.youtube.com/watch?v=9byRp9e2USU

    And my very own step-by-step guide for anyone who's new to using floor pumps with Presta Valves!

    - Move your wheel so that the Presta Valve is at 6 O'Clock (some people prefer 12 O'Clock, but for the Bontrager Recharger Track Pump 6 O'Clock is easier).
    - Remove the black cap. If you lose the black cap, don't worry. It's only for aesthetics.
    - Don't worry about the silver cylinder thing threaded on the valve. Apparently it's not majorly important.
    - Unscrew the little knob at the top of the valve as far as it can go (it isn't removable).
    - Press the top of the knob inwards to make sure it's not stuck. If there's air in the tire, it'll release a bit of air.
    - Place the head of the pump with the bigger hole on top of the knob (on the Bontrager Recharger Track Pump this is the grey head).
    - On the Bontrager Recharger Track Pump, the black head with the smaller hole is for Schrader Valves.
    - Press down so that the head of the pump is fitted on.
    - Lock the lever in place (on the Bontrager Recharger Track Pump the black lever will be pointing upwards).
    - If the head of the pump or the lock is not on properly, or the valve is bent, air will leak or not go into the tire.
    - The pressure gauge on the Bontrager Recharger Track Pump will read 0 PSI, even if there's air in the pump.
    - Pump using just 1 foot on the floor pump (this works best on the Bontrager Recharger Track Pump).
    - Give about 2 or 3 pumps and the needle will move to show what the current pressure is in the tire e.g 20 PSI.
    - I found that at about 80 PSI it seemed like the pump wouldn't work any more and that the tire was full, even though I needed to pump up to 110 PSI.
    - In this case, keep pumping to where you need to be. It's just that the resistance is harder as the tire becomes fuller.
    - Then pump about 2 or 3 times more. This is to replace the air you will lose when closing the valve.
    - Unlock the lever. Quickly pull off the head of the pump and screw the knob back as far as it can be screwed to minimise air loss.
    - Don't push the knob in this time or you will lose air.
    - Replace the black cap and you're good to go.
    Last edited by Dubz; 01-04-2015 at 10:00 AM.

 

 

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