How to Pump Up Bike Tires

Presta valves defeat more beginners than any other part of a bicycle. Here is exactly what to do, in order, plus what to do when it hisses.

By Stephen V.Last updated August 11, 2026How we pick

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If air will not go in, the little nut on top of the valve is still screwed down. That is the answer roughly nine times out of ten, and it is the reason this page exists — more first-time riders give up on pumping their own tires because of that one brass nut than for any other reason.

Below is the whole procedure in order, for both valve types, and then the five things that go wrong with the fix for each.

First, work out which valve you have

Take the dust cap off and look:

Thin, with a small brass nut on top that you can unscrew: Presta. Continue to the section below.
Fat, flat-topped, same as your car: Schrader. Skip to the Schrader section.

Both valve types are unrelated to your tire size, and you cannot change one for the other — the hole in the rim is drilled for one or the other.

Presta valves, step by step

Unscrew the dust cap and put it in your pocket, not on the floor.
Unscrew the small brass nut counterclockwise until it stops. It will not come off — it is captive. This opens the valve.
Press the tip down briefly. You should hear a short puff of air. That confirms the valve is open. If nothing happens, the nut is not undone far enough.
Push the pump head straight onto the valve. Straight on, not at an angle — Presta stems are thin brass and they bend or snap if you lever the pump sideways. Push it far enough that the head covers the threaded section.
Flip the lever on the pump head to lock it. Most modern pumps lock with a lever; some screw on. A brief hiss as you lock is normal.
Pump. The gauge will read zero for the first few strokes while the hose pressurizes. Stand over the pump and use your body weight rather than your arms.
Stop at your target pressure (see below).
Flip the lever back and pull the head straight off, quickly. The short hiss is the hose emptying, not your tire.
Screw the brass nut back down finger-tight. Do not use tools.
Refit the dust cap. It keeps grit out of the valve.

Schrader valves, step by step

Simpler, because there is nothing to open:

Unscrew the dust cap.
Push the pump head straight on and lock it.
Pump to your target pressure.
Unlock and pull off.
Refit the dust cap.

If your pump has a two-hole head, use the larger hole. If it has a smart or auto-reversible head, it detects the valve for you and there is nothing to change — which is exactly why we recommend those on the pump page.

What pressure to aim for

The number molded into the tire sidewall is a maximum, not a recommendation, and running to it is one of the most common beginner mistakes — especially on gravel, where it makes the bike skittish and harsh.

Reasonable starting points:

25–28mm road tires:80–100 PSI
30–35mm:50–70 PSI
38–42mm gravel:35–50 PSI
45mm and wider:25–40 PSI

Heavier riders go higher within each band, lighter riders lower, and rougher surfaces lower still. Our tire pressure guide works through how to find your own number rather than leaving you with a range.

Five things that go wrong

1. No air goes in at all

The brass nut is still down. Unscrew it fully and press the tip to confirm you hear air.

2. The pump reads a pressure but the tire stays soft

The head is not fully seated, and you are pressurizing the hose rather than the tire. Take it off, push it on further, and lock it again.

3. Air escapes continuously when you remove the pump

The valve core has unscrewed itself, usually because it was gripped by the pump head as you pulled off. Screw it back in gently — finger pressure with the valve nut, or a valve core tool if you have one.

4. The valve bends or snaps

Levering the pump sideways. There is no repair; it needs a new tube. Support the wheel rim with your free hand while you push the head on, and always pull straight off.

5. The tire will not hold pressure at all

That is a puncture, not a pumping problem. See how to fix a flat tire.

How often, and why it matters

Weekly at minimum, ideally before every ride. Bicycle tubes are permeable — air migrates out through the rubber whether you ride or not. Narrow high-pressure road tires lose pressure noticeably within a few days; wide low-pressure gravel tires hold on longer.

Riding on soft tires is not just slower. It causes:

Pinch punctures, where the rim squeezes the tube against an edge and cuts two parallel slits. The most common flat on gravel.
Vague, wallowing handling in corners.
Rim damage if you hit something hard with a nearly flat tire.

The check takes ten seconds once the pump lives where you park the bike, which is the practical argument for owning one rather than borrowing one.

Questions people actually ask

Why won't air go into my Presta valve?

Almost certainly because the small brass nut on top of the valve is still screwed down. Unscrew it counterclockwise until it stops — it does not come off — and press the tip briefly to confirm you hear a puff of air. This one step is the single most common reason a pump appears to be broken.

What is the difference between Presta and Schrader valves?

Schrader is the fat valve your car uses, with a spring-loaded pin inside. Presta is the thin one with a brass nut on top that must be unscrewed before air will go in. Almost every road and gravel bike uses Presta, because the narrower valve needs a smaller hole in the rim.

How much air should I put in my bike tires?

It depends on tire width, your weight and the surface — and the number printed on the sidewall is a maximum, not a recommendation. As a starting point: 80 to 100 PSI on 25 to 28mm road tires, 40 to 60 on 32 to 35mm, and 30 to 40 on 40mm-plus gravel tires. Then adjust from there.

Why does air hiss out when I remove the pump?

That hiss is the pump hose emptying, not your tire. It is normal and it lasts under a second. If air keeps escaping after the pump is off, the valve core has probably loosened — screw it back in gently with your fingers or a valve core tool.

How often should I pump my bike tires?

Weekly at minimum, ideally before every ride. Bicycle tires lose pressure through the tube wall whether you ride or not, and narrow high-pressure road tires lose it noticeably within a few days. Riding on soft tires is slow, uncomfortable, and the most common cause of pinch punctures.

Can I use a car tire pump on a bike?

A gas station air line will fit a Schrader valve, but it delivers air far faster than a bicycle tire can take and the gauges are calibrated for car pressures — it is a good way to burst a tube. It will not fit a Presta valve at all without an adapter. Use a bicycle floor pump.

Sources

Specifications come from the manufacturer or the retailer listing, dated. Where a figure is not published, we say so rather than estimating it.

Silca — Professional tire pressure calculator — Published pressure model taking rider weight, tire width and surface as inputs (accessed July 23, 2026)
WTB — Frequently asked questions — WTB's own tire pressure guidance for high-volume gravel tires (accessed July 23, 2026)
Schwalbe — Tire sizes and the ETRTO designation — How the 40-622 style ETRTO number maps to '700 x 40c' (accessed July 23, 2026)