I should clarify that I have the most trouble trying to attach the chuck, and keep it attached, when connecting to a completely flat tire. Half of the problem seems to revolve around the way the entire stem wants to disappear into the rim and tire while I’m trying to attach the chuck. With a completely flat tire, I simply can’t get the chuck to grab enough of the stem to get a grip. Maybe I can “fix” this by finding tubes with the longer stems.
I also have an odd issue wherein, even if I do get a solid connection, I encounter a ridiculous amount of resistance when I try to pump the air into the tire. Even when the tire is completely flat and there should be no back-pressure. I have no idea what could be causing it, and had the same issue with my previous pump and multiple tubes. But it doesn’t happen every time, and I can’t spot any pattern to what’s causing it. Sealant in the tube? (We have a lot of goatheads around here, so it’s sensible to run thorn-resistant tubes with sealant.)
If the valve disappears into the rim, it has no locknut on it. This is a thin ring of a nut that you would tighten toward the rim. I’m not sure all Presta valves are threaded all the way up the hilt, but some are.
Some pumps are adjustable to make them grip the stem tighter. This might be a knurled gland nut at the very end off the fitting.
And if there isn’t enough of the valve protruding above the locknut, then you need a tube with a longer valve. Tubes are available with different length valves.
Can you try a different pump at your local bike place?
I have to jump on the bandwagon of the first half a dozen posts. The presta valve on my own new-ish road bike is the easiest tube to keep inflated i’ve ever had. I can literally connect it, pump to my PSI and disconnect it in about 60 seconds, with no trouble whatsoever.
For a flat tire, hold the tire on the outside of where the stem is as you put the pump on so it doesn’t disappear too much, or use the stem nut if it came with one (I throw them out). Some tubes have longer stems than others, if you have to, change brand of tubes.
Are you using the lever to lock the pump to the stem?
The purpose of the cap on a presta valve is to prevent the valve end from damaging the tube when it is all folded up in the box (or in your saddle bag.) Once the tube is on the wheel you can throw it away. A schrader valve needs the cap though as it prevents something from getting into the stem and pushing the valve open.
Yeah, it sounds like you need longer valve. When you buy your next tube, try one that’s a bit longer. I use a 48 mm tube on my bike. And I always use the lock nut.
Everybody’s wrong. The problem is that he needs a worse bike. A one-speedHuffy beach bike has Schrader valves and nice, thick tubes that don’t leak. It gives better (more) exercise in every way, especially on hills. Or getting it into the bike rack on the roof of your car. Cadence, schmadence. Always pedalling at your most comfortable rate is too efficient, and isn’t good for you. Interval training’s where it’s at now.
Better keep it outside, though. That Ferrari you own might pout if it has to share a garage with it.
Yeesh, WallyWorld has an off brand one with an aluminum frame and rims for a buck, too. Nine pounds lighter. No white walls.
This happens to me too. It is the valve sticking from friction. If you simply press in the valve after unscrewing it open, then you won’t have the problem of the initial air pressure having to unstick the valve. The longer the valve has been closed the more it seems to stick closed.
I always used the stem nuts on my old mountain bike (got stolen some years ago), and never had any real problems using presta valves with my Zefal pump.
The only thing that was kind of a pain was trying to use the Presta adapter with my air compressor; never did get that to work quite right.
Let’s compare your bike tire to a car tire. There are a few key differences that explain why your bike tire can lose several PSI per day while your car tire may lose just a couple of psi per year.
First, the inner tubes are porous. Butyl rubber has relatively low permeability (compared to other polymers that could be used in this application) for O2 and N2, but it’s not zero. Cars have a nice thick layer of it on the inside of their tires to limit the egress of air. OTOH, the inner tubes on your bicycle are paper-thin to keep weight to a minimum. For a given psi, the mass flux (mass per unit time per unit of tube surface area) through your bicycle tires will be substantially higher on this basis alone.
The shape is different, too. Take a car tire and a bike tire, and for each one, divide its surface area by its enclosed air volume. The bicycle tire will have a far higher ratio, which tells you that for a given amount of air mass escaping, the bicycle tire will experience a greater psi drop.
And then there’s the fact that car tires are tubeless - meaning about half of the surface area exposed to compressed air is the impermeable steel or aluminum of the rim. So take your car tire’s surface-area-to-volume ratio, calculated in the previous paragraph, and cut it in half again.
Finally, the pressure. The permeation of air through the tire is driven by air pressure - specifically, the difference in pressure between the inside of the tire and the outside. You car tire has about 35 psi in it, but your bike tire, depending on model, could have well over 100 psi. That alone guarantees about 3X the mass flux for the bicycle tire versus the car tire.
So if you want your bicycle tires to lose less psi per day, be prepared for some changes:
-a thicker, heavier inner tube
-a larger tire volume
-a lower pressure in the first place
I’ll probably just be repeating what everyone else said but here goes.
Is your presta valve threaded on the outside? Smooth valves are more difficult to keep attached to the pump. If smooth, try threaded presta valve tubes next time. Also when using a threaded presta valve, do use the little curl nut. Some people think that they aren’t cool and weigh alot (about a gram! Oh My!). However they will keep the presta valve from pushing into the rim when inflating a low tire and possibly keep the tube from getting torn. I’ve also seen them quiet a noisy ticking sound when using long valve stems such as 60 mm.
Frame or floor pump? I use a Specialized floor pump for inflating my bike tires except in an emergency when I use a little frame pump. My Specialized floor pump is excellent. It automatically adjusts for presta and schreader valves. Also it’s never pulled the presta vavle or valve guts out when removing the pump head like others.
If a frame pump, see if you can tighten down the head some. Many such pumps have reversible parts so that you can switch them from presta to schreader. Often tightening down the head will help it grip the valve stem better on both presta and schreader valves.
Sometimes you need to ‘burp’ the presta valve to get air to go in it easily. In other words leave a little air out so that the pump can overcome the internal pressure readily.
I don’t go more than 2 days between airing up my road bike tires before a ride. High pressure gasses can escape very easily from rubber tires and tubes. When I worked on aircraft, we check the tire inflation before the first flight of the day for this reason.
If you think air is bad, just wait until you get a CO2 inflator. Bicycle tires and tubes are very permeable to CO2 gases.
And really, Rik, if you’re inflating your bike tires with your ass, I’m not surprised it’s painful. Whether Schrader or Presta, the valvestem is just anatomically wrong for that.
And no matter how gassy you may be, it probably won’t be enough pressure to inflate a road tire.
(I figured I’d start in with the joking responses now that it appears that the thread has fulfilled its GC charter and answered your factual question.)
