How to pump up a bike tyre — everything you need to know about pumps, valves, pressure and more (PART 2)

How does a pump work?

A pump gets the air in your tyre. The operating principle is simple; you increase the pressure inside the pump until it exceeds that inside the tyre. This ‘overpressure’ forces air into the tyre, increasing its pressure too.

A pump is just a manually actuated piston. On a pump’s downstroke, a check valve (allows air-flow in one direction) seals the piston chamber, resulting in air being pressurised as the pump is compressed. That pressure increases until it exceeds that inside the tyre.

At this point, a second one-way valve will allow air to flow from the pressurised pump chamber into the tyre. You extend the pump again, the check valve opens to refill the chamber with air and you repeat the process.

To prevent the pressure in the tyre leaking back out, the second check valve at the base of the pump closes. If it wasn’t there, the pump would just shoot open again.

Presta valves will close automatically, but the sprung Schrader valves are usually held open by a pin in the pump valve attachment (this means you don’t need any extra effort when pumping to overcome the pressure exerted by the spring.)

The chuck is the part that attaches the pump to the valve and forms an airtight seal over the valve. One of two designs exist: threaded or push-on with a locking lever. Most pumps nowadays are also adaptable to either Schrader or Presta valves.

They will either feature two different attachment points or an adjustable chuck that can be changed to suit both types. For larger pumps (and many mini-pumps too) the chuck is often on a hose, preventing your pumping force from damaging the valve.

Pumps will often include a pressure gauge to check the pressure inside your tyre.

How to pump up a bike tyre (Schrader valve)
How to pump up a bike tyre — everything you need to know about pumps, valves, pressure and more (PART 2)

If you’ve got a Schrader type valve such as this one then the first thing you need to do is remove the dust cap (if there is one in place).  Oli Woodman / Immediate Media

How to pump up a bike tyre — everything you need to know about pumps, valves, pressure and more (PART 2)

Simply unscrew the cap anticlockwise to reveal the valve.  Oli Woodman / Immediate Media

How to pump up a bike tyre — everything you need to know about pumps, valves, pressure and more (PART 2)

Now attach the head of your pump.  Oli Woodman / Immediate Media

How to pump up a bike tyre — everything you need to know about pumps, valves, pressure and more (PART 2)

Inflate the tyre to a value between the minimum and maximum stated on the tyre sidewall and remove the pump. You’re done!  Oli Woodman / Immediate Media

How to pump up a bike tyre (Presta type valve)
How to pump up a bike tyre — everything you need to know about pumps, valves, pressure and more (PART 2)

If your bicycle has a Presta type valve such as this one then you will first have to remove the plastic valve cap (if fitted).  Oli Woodman / Immediate Media

How to pump up a bike tyre — everything you need to know about pumps, valves, pressure and more (PART 2)

The plastic cap will reveal another threaded cap to the valve.  Oli Woodman / Immediate Media

How to pump up a bike tyre — everything you need to know about pumps, valves, pressure and more (PART 2)

Unscrew the thread but be careful to not damage it in the process.  Oli Woodman / Immediate Media

How to pump up a bike tyre — everything you need to know about pumps, valves, pressure and more (PART 2)

Now attach the head of your chosen pump to the open valve and inflate the tyre to a pressure that’s between the minimum and maximum stated on the tyre’s sidewall.  Oli Woodman / Immediate Media

How to pump up a bike tyre — everything you need to know about pumps, valves, pressure and more (PART 2)

Inflate the tyre to the desired pressure and remove the pump.  Oli Woodman / Immediate Media

How to pump up a bike tyre — everything you need to know about pumps, valves, pressure and more (PART 2)

Finally, close the valve by screwing it clockwise and reinstall the plastic valve cap.  Oli Woodman / Immediate Media

What type of pump do I need?

We’d say that if you own just one type of pump, get a track pump for home use because it’s efficient, quick and easy to use. However, there’s no doubt that having an additional mini-pump for when you’re out on the road is rather useful – otherwise you risk being stranded at the road side in the event of getting a pump.

We’ve already got a guide on choosing the best bike pump for your needs, but here a few recommendations for you to consider.

Track pump

The sky’s the limit with track pumps. They basically all do the same job, some with a more premium feel than others.

From a budget Park Tool PFP8 to the absurdly expensive Silca Pista Plus, you’ll be able to find something that suits your needs.

Mini pump

Mini pumps work but are a lot more frustrating to use. Again, there are lots of options available from mini track-style pumps to tiny pumps that will fit in a jersey pocket. We tend to prefer mini pumps with a hose because that reduces stress (and potential damage) on the valve.

Two of our favourites have been the Truflo TIO Road and the Lezyne Micro Floor Drive HP.

CO2 inflator

One other possibility for your inflation needs are CO2 inflators. These use compressed carbon dioxide in a small cartridge to inflate or top up a tyre really quickly. Not something you would want to use on a regular basis, but perfect for an emergency repair.

How to use your pump to inflate a bicycle tyre

The first thing to do is attach your pump to the valve. Remove the valve cap, and regardless of valve type, we find it’s good to release just a little hiss of air to ensure the valve isn’t stuck and opens and closes cleanly. Either thread on the chuck, or push it on and lock it.

If your tyre is completely flat it may initially be a bit of a struggle to fit the chuck as the valve has a tendency to push back into the rim. Simply hold the valve from behind by pushing on the outside of the tyre so that you can lock the chuck on properly.

The lockring on Presta valves (if fitted) can also help, preventing the valve from disappearing by holding it in place for you.

The connection to the valve should be air-tight. A little escaping air is normal when attaching the pump, but shouldn’t continue for long. If it does, remove and reattach the chuck. If it continues to be a problem it may be worth checking the rubber seal in the chuck to see if it is worn out and needs replacing.

Remember to be gentle with the valves — they’re delicate. That’s especially the case if you’re using a mini pump without a hose. Make sure to brace the pump with your hand wrapped around the spokes or tyre to avoid transferring too much of the pumping force to the valve, which could lead to damage.

When you start pumping make sure to use the full stroke of the pump. You’ll find that the majority of the stroke is taken up compressing the air to the point where it will then be pushed into the tyre.

If you don’t use the whole length of the pump, the air won’t be pushed out of the bottom — you need to generate overpressure in order to move the air from the pump to the tyre. Instead, you’ll just end up with the shaft bobbing around doing nothing.

With a track pump, don’t just use your arms, use your body weight for the downstroke and pumping will become a lot easier.

You may sometimes find that the pump doesn’t seem to hold pressure, especially when inflating the tyre from completely flat. This may especially be the case with an older pump where seals may be slightly sticky.

We find it helps to pump vigorously initially, to generate enough back-pressure (i.e. pushing back from the tyre side) in the system to ensure that valves are actuated properly and seal up, in turn inflating the tyre. Keep on going until you get the right pressure.

When removing the chuck from the valve there is usually an audible hiss of air being lost. This is usually from the pump rather than the valve side. Pressured air in the hose and chuck is just escaping.

Tubeless considerations

If you have a tubeless setup, or tubes setup with sealant inside, then it’s worth taking a few extra steps to avoid gunking up your pump.

Turn the wheels so the valves are at the bottom and leave for a few minutes so any sealant can drain out. Turn the wheels so the valves are at the top and pump up your tyres. The same goes when deflating tyres to prevent goop spraying everywhere.

What pressure (psi) should my bike tyres be?

The right tyre pressure is perhaps one of the most contentious subjects, but there are definitely a few guidelines that you can use.

As a general rule, your tyre should be solid enough to prevent the tyre deflecting all the way to the rim, though compliant enough to provide some suspension — after all, the beauty of a pneumatic tyre is that you don’t have to have a bone-jarringly hard ride.

Most tyres will have a minimum and maximum pressure rating printed on the side. It’s advisable not to go under or over those limits because manufacturers have specified them for a reason. Of course, that means there’s still a lot of room to play with pressure and what works for you.

Traction

For mountain bikes the problem is relatively easier, with the usual aim being to improve traction, cornering and shock absorption. As a general rule riders try to run as low a pressure as possible without having it so soft that the tyre squirms under cornering load or deflects enough for damage to occur to the rim.

Rolling resistance

For road bikes it becomes a little more complicated because along with traction and comfort, rolling resistance (how efficiently a tyre rolls) is a major consideration as well. Contrary to what many assume, the new school of thought seems to suggest that harder is not necessarily faster.

On all but the smoothest of surfaces, a hard tyre will not have as much suspension, and instead of the tyre being able to deflect and conform to irregularities — keeping the bike moving forward — you will get bounced around. On all but the flattest of surfaces softer tyre pressures can provide more comfort and be more efficient.

The most comprehensive research into this was underatken by Frank Berto, who put together a tyre pressure inflation chart. This testing determined that a 20 percent tyre drop (the amount the tyre compresses when load is applied, measured by the height from the ground to the rim) was the optimum balance.

Incidentally, some manufacturers recommend a similar level of tyre drop, though the figure is open to some debate.

This value does provide a good starting point to experiment with tyre pressures. The chart looks at individual wheel load — i.e. your and your bike’s weight on each wheel (40 percent front / 60 percent rear is a good starting point) — and calculates the pressure for each accordingly.

How often should I pump up my tyres?

You need not always get your pump/gauge out to check for tyre pressure.  BikeRadar / Immediate Media

It’s a good idea to check your tyres before each ride. Usually that just involves giving them a squeeze by hand to check the pressure. No, it’s not super accurate, but you’ll quickly get a feel for the pressure in your tyres and be able to tell whether they need pumping up or not.

If you start to get really nerdy about it, you may end up investing in a pressure gauge, which can read the pressures in your tyres very accurately. That’s especially helpful for mountain bikes where a few psi can make a large difference to handling and grip, but equally applicable on a road bike to find the exact pressure that works for you.

Take your first steps towards perfect pressure bliss.