Help me pump my bike tubes

September 24, 2022 5:03 PM

I'm not sure why this is so complicated but I really struggle with pumping my bike tubes. Help?

I have a cheap model Blackburn floor pump, and presta valves on my tubes. Photos here: inside, side view.

EVERY TIME I try to pump up my tires, some variety of the following happens:

- the pump head won't stay attached to the valve stem. If I try lifting the handle to lock the pump head into place, it just doesn't work: the air won't pump out?
- so, I end up pushing the pump head down, and somehow my tire deflates all the way.
- if I try pumping air, the pump head flies off the valve.
- in order to pump effectively, I need to hold the pump head with one hand or foot so it stays on. It's very inefficient, hard on my back, and I feel like I'm bending the valve stem.

What am I missing here? Do I need some sort of attachment? Do I just need a new pump? I've tried watching videos and I don't think I'm making any basic mistakes (e.g. I know how to unscrew the prestas). Any help would be majorly appreciated.

posted by Paper rabies to Sports, Hobbies, & Recreation (15 answers total)

I think you're like 99% there.
Loosen the valve,
Lever on the pump is down,
Put pump on valve,
Hissing starts,
Lever goes up to lock on,
Pump to desired pressure,
Lever down, pump off, tighten presta

I think the thing you might be missing is that the pump head should be causing air to leak when you first push it on, and that locking will stop that sound.
posted by Acari at 5:52 PM on September 24, 2022 [1 favorite]

The pump looks like it's set for Schrader valves. Quite often - if the head doesn't have two outlets - you have to undo the knurled bit at the end of the hose and flip part of the core/washer over.
posted by scruss at 5:54 PM on September 24, 2022 [4 favorites]

In my experience, prestas are a bitch: stems can be too short, pumps lock doesn't engage correctly... even for old pump hands, they don't behave all the time. So don't think you're doing something wrong.
Regardless. There are things called schrader adapters. They thread onto a presta valve and operate as a schrader does. This means you can use them on the air pumps at gas stations as well as the schrader pump at home. They can also serve as valve caps.
At my local bike shops they're sold for something less than a dollar, or free, if you call them by name when you're buying something else.
posted by Cold Lurkey at 6:05 PM on September 24, 2022 [3 favorites]

Some pumps are just terrible, have you tried any other pumps?

Two tips that haven’t been mentioned, when you unscrew the presta valve, press it down and let out a tiny bit of air. The valves can stick shut; don’t rely on pressure to open them. This is often the problem when you pump and it doesn’t go in, then shoots the head off.

With tricky pumps, I make sure that I can hold on to something on the valve when I push the head on. Sometimes, that’s the stem through the back side. Sometimes, I can squeeze the base through the sidewalls. If your tube has the screws that holds the stem to the rim, that helps a ton too. Press that head way down and flip the lever. Sometimes you put a little air in there and you can flip the lever open again and push it tighter and flip the lever closed again
posted by advicepig at 6:51 PM on September 24, 2022

Further to my last comment, it seems that newer Blackburns have a head that claims to auto-adjust for Presta and Schrader. The ones that do should have "Presta/Schrader" on the front of the knurled ring: I didn't see that in the OP's picture.

Presta valves can be finicky and need a certain approach, true. For me, they're much less work than Schrader, and frankly, the less said about the Woods/Dunlop valves that come on roadster bikes, the better.
posted by scruss at 6:54 PM on September 24, 2022

Without watching you use this pump, it's hard to say what's wrong. I often find with Presta valves that I need to tap the stem after loosening the nut, in order to break the seal so it will fill easily.

Is it possible you aren't sliding the chuck far enough onto the valve?

In any case, I prefer Lezyne pumps, which thread onto the stem; their pumps have a flipper chuck so that you need to remove the chuck and screw it onto the hose the other way around to switch between Presta and Schraeder.
posted by adamrice at 7:17 PM on September 24, 2022 [2 favorites]

I was also going to recommend Lezynes. Admittedly my bike has Schraders, but I quit having valve-stem flats when I switched from a cheap Schwinn pump to a screw-on Lezyne. They're pricey, but so far mine has lived up to the hype.
posted by humbug at 8:13 PM on September 24, 2022

To me, it looks like the pump is Schrader valves. Schrader and Presta are completely different so if your pump only has one hole than it's one or the other. Can't be both.

Pumps that do both look like this, with two holes (right side pic).

In order to pump air into a valve with a lock-toggle on it, it needs to be in the position that matches the middle photo in that link. If it's in any other position, it's "closed".

I've never encountered a Presta valve that didn't require the switch to not be straight, as in the middle photo.
posted by dobbs at 8:37 PM on September 24, 2022 [1 favorite]

Also, just to be clear, a Presta valve looks like this.

The tip of the valve, at the top (gold in the picture), needs to be loosened (counter clockwise) until it reaches the top of the valve, before the pump is attached. You then pump it to the required pressure, remove the pump, and turn the gold bolt counterclockwise until it reaches the position in those photos.

So:

1. Turn the gold part counterclockwise until it reaches the end of the valve.
2. Attach pump.
3. Pump air.
4. Remove pump.
5.Turn gold part clockwise until you can't, locking in the air.
posted by dobbs at 8:43 PM on September 24, 2022 [1 favorite]

Response by poster: Thanks for the feedback, folks. A few comments:

- I tried going into a bike shop and asking for a Schraeder adapter (which I assume is this type?), and the guy treated me like I was a total idiot. He told me that most modern pumps work for both valve types. I'll try picking one up somewhere more helpful.
- As I noted, I do know how to loosen/tighten the presta valves. I don't normally depress the valve before putting on the pump head to let a bit of air escape (as advicepig said). I'll give that a shot.
- I don't have any luck when I try locking the pump head: it always seems like the air won't come out at all.

I might just get a new pump though, so thank you for the recommendations!
posted by Paper rabies at 10:52 PM on September 24, 2022

I think scruss might have it. Try unscrewing the ring on the end of your pump head, and shaking the innards out gently. You may find a rubber gasket and a small plastic part. On some pumps you can reverse each of those and put them back in to convert the pump head.

An adapter is still worth picking up at some point from a friendlier shop as it let's you top up at a gas station.

Also, pumps that do both with only one hole exist... for example the one in my shed that I can't remember the name of. I don't think this pump is that type though.
posted by snoboy at 11:49 PM on September 24, 2022

Sorry you got treated that way at the shop, OP. Most “normal” shops have presta adaptors in a small display by the counter.

Also not really understanding the hate for presta valves. They’re way easier than schraders!

Most likely the issue is with your pump.
posted by computech_apolloniajames at 1:09 AM on September 25, 2022

+1 for scruss' advice, it looks like your pump is set for Schrader valves — so undo the knurled ring, take out the rubbery parts and reverse them to set it up for Presta. The bike shop chap — though rude — is correct that most modern pumps don't need an extra adapter.

Here's my hand pump being reconfigured from a Schrader setup (wide opening) to Presta (narrow opening).
posted by Klipspringer at 4:15 AM on September 25, 2022 [2 favorites]

Schrader and Presta valves work very similarly. Both have a mushroom-shaped valve element inside that's pulled back against a seal on its seat by the pin that forms the mushroom's stem. Once seated, air pressure inside the tube adds to the force pressing the valve head back into its seat.

In a Schrader valve, the force to pull the stem pin back against the seat comes from an internal spring that sits around the stem. In a Presta valve, the stem is longer and extends all the way to the outside of the valve body, and the user tightens a knurled nut threaded onto its end to pull the valve closed.

Both designs expose much more of the surface of the valve head to the air inside the tube than they do to the air outside it. This makes the pressure difference between inside and outside air exert even more outward force on the valve head than can be accounted for by the air inside typically being at least four times atmospheric pressure. Opening the valve so the pump can push in more air, then, always needs the pin to get forcibly shoved back inward as the pump fitting is applied to the valve.

Fittings designed to work with Schrader valves do this by having a small fixed pin in the centre of the fitting. When the fitting is pushed all the way home, that pin engages with the end of the spring-loaded stem in the valve, compresses the spring, and pushes the valve open. Air hisses out through the valve at this point until a good seal is established between the fitting and the valve tube. Service-station air hand pieces generally do that using a simple ring seal that the user needs to maintain pressure on to keep the joint sealed. Fittings designed for the ends of hoses include some kind of clamp that compresses a soft rubber ring around the threaded outside of the Schrader valve's tube, sealing it that way. In either case, fitting a pump to a Schrader valve properly will cause a brief hiss of released air very quickly stopped by the fitting being properly locked in place.

Presta fittings work almost the same way except that because there's no internal spring holding the valve in place, there's no need for a rigid centre pin to act against one. So if you look down the end of your pump's fitting and you see a centre pin, it's almost certain that it's been set up for Schrader valves, not Prestas.

Trying to use a Schrader fitting on a Presta valve fails in some absolutely characteristic ways:

1. The fitting's centre pin encounters the loosened nut on the end of the Presta valve pin about 5mm earlier than the slightly recessed Schrader valve pin it's expecting, so the valve opens early.

2. The Presta nut takes up space inside the fitting that a Schrader valve tube wouldn't, so the fitting can't engage with as much of the valve tube as it's designed to. Attempting to ram it home as far as it will go can push the Presta nut so firmly into the end of the valve tube as to block it almost completely.

3. The exposed metal parts at the end of a Presta valve tube are narrower than the metal threads that a compression-type Schrader fitting is designed to seal against, so not only is the resulting seal region much shorter than it should be, the seal is nowhere near as tight.

(2) and (3) together mean that when air pressure is applied to the fitting, it's almost certain that it will pop the fitting off the valve instead of forcing air through it.

Sometimes it's possible to hold a Schrader fitting onto a Presta valve stem by hand, hard enough and sensitively angled enough that the seal just about holds and you do get a bit of air inside the tyre, and if you didn't understand that the wrong fitting was in use you might easily conclude that the pump is just badly made or faulty. From your description of what happens when you try to pump air, I'm quite convinced that that's what's going on in this case.

Once you've followed Klipspringer's procedure for getting your adapter set up correctly for your valves, I think you'll come to appreciate the way that the Presta valve's larger internal air paths compared to the Schrader's reduce wasted effort during pumping.
posted by flabdablet at 5:23 AM on September 25, 2022 [1 favorite]

Trying to use a Presta fitting on a Schrader valve also has characteristic failure modes:

1. The compressible rubber insert inside a Presta fitting has a smaller bore than that of a Schrader fitting, and this might make for a bit of a struggle getting the fitting onto the valve at all.

2. If the fitting does go onto the valve, there will usually be no difficulty in getting it to cover enough of the valve tube's external threads to compress into a good seal. But because there's no fixed centre pin in the fitting, the Schrader valve remains locked closed under spring tension.

3. The fitting's ring compression lever will often refuse to move far enough to lock itself into position.

The net effect is that even if you actually manage to get the fitting locked on, it's usually impossible to get any air out of the pump. And if the pump is indeed capable of raising the pressure inside the fitting enough to force the valve open despite the spring holding it closed, that's also usually more than enough pressure to leak noisily past the threads or even pop the fitting off the valve tube entirely.
posted by flabdablet at 5:36 AM on September 25, 2022 [1 favorite]