Track pump gets to 90psi then wont pump anymore air in??

[RSV_Ecosse]

Hi.

I bought a track pump yesterday from Tesco, the one for under a tenner with the pressure gauge built in.

Couple of questions, as I'm a newbie and I haven't used a track pump before.

1. The tyres on my FP1 are supposed to have @120psi in them, but when I try and inflate them to that pressure, I get to about 90psi and it becomes pretty impossible to pump anymore air into them?. If I force my entire bodyweight down on the handle, I can get a couple more psi in, but am I doing something wrong?.

2. The bit that fits over the valve on the rim, it seems like I have to push it on overly far down onto the valve for it to get any sort of seal and allow air to be pumped in, is that normal?.

I'm thinking perhaps the two issues are maybe connected?.

Thanks.

 

[ChrisKH]

First off, are your valves presta or schrader? Presta are the valves that unscrew (I think) schrader like a car valve.

If I use my track pump for presta valves I have to make sure a) the valve is fully undone and the pump head is pushed as far on to the valve as possible to make contact. Otherwise it looks like it's pumping air in (ie the gauge goes up) but nothing actually is. This would give the same problem you are experiencing, and no air is making its way past the valve into the tyre. Just a thought.

Your point 2 appears to reinforce what I am saying.

 

[RedBike]

1) It's a cheap pump. I can pump my tyres up to 120 one handed no problem.

2) For presta valves the pumps head normally has to be pushed on as far as possible. As you start pumping the valve normally stays shut then as you reach a higher pressure than whats in the tyre you can hear the valve open and the pressure reading on the gauge drops slightly.

 

[LLB]

90psi is a good pressure for the roads around here. 120psi gives a very hard ride.

I've got a red track pump (halfords own) for £20 and it does the job to whatever

 

[John the Monkey]

1) Applies here, I think. Cheap track pumps tend to be a false economy - I had several, a Vento (crap, managed 60ish before it began to leak air) a Lidl (ok, until the valve head began leaking air a month or so after I bought it) and an Aldi (surprisingly good, but rated to 100psi and doesn't go higher - this is ok for my commuting tyres which have a recommended pressure of 95psi).

I got hacked off with them and spent £36ish on an SKS Rennkompressor from Parker International. The gauge goes up to over 200 psi, as I recall, and I've every confidence that my tyres/wheel would fail before the pump did. As it is, it manages 120 without any problem at all.

 

[gratts]

Bikehut shock pump from halfords - £20, claims to get to 300 psi.
Even if it gets nowhere near that it can easily manage 120
It's pretty small, so v. portable, takes a lot of pumps though!

 

[ColinJ]

I answered a very similar question over on BikeRadar recently - here.

On second thoughts, they might delete my post at some point. Here's a copy of what I wrote:


After you unscrew the valve, you need to press the end in to let some air out. When you try to do that you will probably notice that the valve was stuck and it takes quite a bit of a push to loosen it. More than your pump could have managed in fact. Once you've manually 'unstuck' the valve, reattach the pump and it should work properly when you try again.

PS

When you try pumping up a tyre with a valve stuck, it acts exactly the same as if you haven't unscrewed the end of the valve. As you use the pump, you'll feel an incredible amount of resistance, the pressure gauge reading will shoot up, but the tube won't inflate. All you are doing is raising the pressure in the pipe between the pump and the valve. Eventually you'll blow the pump head off the valve.

When you have unscrewed and loosened the valve as described above, you will still observe the same process mentioned in the previous paragraph, but when the pressure from the pump exceeds the pressure in the tube by an adequate margin, the valve will suddenly open (you'll hear a clicking sound when this happens), air will rush into the tube and you'll finally be getting somewhere!

 

[4F]

1) It's a cheap pump. I can pump my tyres up to 120 one handed no problem. .

Yep agree. I tried one of those LIDL pumps as a back up a while back and it would go to 90psi but no chance of anything over this. It soon went back

My specialized pump easily gets up to 110

 

[swee'pea99]

FWIW, when I do mine, the first thing I do after unscrewing the unscrewy bit is to briefly tap it with the connector bit of the pump - just a split-second tap to 'break the seal'.

 

[jimboalee]

ColinJ.

Absolutely Correct.

Remove the dust cap. Hold it in your teeth.
Loosen the knerled lock nut.
Before you attach the pump head, tap the presta pin with the side of the pump head to unseat the valve. PSST....
Attach the pump head and operate its locking lever.

Inflate tube.....

 

[Smokin Joe]

It's nothing to do with a sticking valve as he can get 90psi into the tube, if the vave was stuck nothing would go in.It's just a crap pump. I got a cheapo from Probikekit a couple of years ago and anything over 80 was pure agony.

BTW, don't confuse the meaning of pressure rating on a pump. If a pump is rated to 175psi that is the pressure it can take without blowing the hose and the seals, not what it is physically capable of putting into the tube. Anyone who has bought a 140psi rated mini pump that won't get more than about 60 into the tube will know what I mean.

 

[RSV_Ecosse]

Cheers guys, thanks for the input.

I'll give it another go tonight before I hit my kip, in preparation for my ride to work tomorrow morning.

Probably right about it just being a crappy pump. Can't expect much for a tenner I 'spose.

 

[ColinJ]

It's nothing to do with a sticking valve as he can get 90psi into the tube, if the vave was stuck nothing would go in.It's just a crap pump. I got a cheapo from Probikekit a couple of years ago and anything over 80 was pure agony.

If he can pump the tube up from flat, and then he gets stuck, then you are right.

If the tyre happens to be pretty well pumped up already but he is trying to get even more air into it and he thinks that he is doing that because the pressure shown on the gauge keeps rising, but then it seems to get stuck, that could be my scenario.

Anyway, a decent track pump should be able to manage well over 100 psi with ease. I use an older model of this Specialized pump and it works really well. Mind you, just because a tyre is rated to a certain pressure doesn't mean that you have to go to that. I usually use about 80 psi front, 90 psi rear for my 25C tyres, and 90 front, 100 rear for 23C tyres. That's a different discussion though, and it has been brought up many times before.

 

[nigelb]

I've just got one of these too, and it does seem to get very hard work over 90psi.

However, up to that point it worked fine, took mine from ~40 to ~90 very fast, and the tyres certainly feel a lot harder (I could hear the air going in too whilst I pumped).

I'm on Continental 700x25C, they say 100 psi please, I'm hoping 90 is close enough.

Nige

 

[yello]

Remove the dust cap. Hold it in your teeth.

I like the attention to detail!

I too suspect the answer is to do with the quality of the pump.