inflating tyres with the small valves

rowanh

Hi, i got an adapter for the small bike tyrevalves yesterday but when i tried to inflate them in a petrol station it didnt really work, one seemed to get a bit harder but not much and the other not at all, the pressure was coming up around 40 psi. I went to another petrol station, i noticed there that you have to unswrew the valves, one was already unswred which is why it was working a bit. I still couldnt get the pressure to go about 50 or 60, it seemed like when it was on 60 i would put air in it then it would drop down to 50 or lower. Im wondering am i doing something wrong or it the adapter not working or maybe there is someone wrong with the valves? It did kind of look like the distance from the thing inside the pump that pushes the vavle in was farther away than the valve pin in the adapter but hard to tell really. Any ideas would be much appreciated.

Rowan

victorcarrera

Thats a presta valve you have with the screw on tops.
Is it possible that you are using a shrader to dunlop adaptor which would not have a good seal.
I wouldn't use a petrol station pump. They are very inaccurate and too powerful for small bicycle tubes. Better to buy a hand or floor pump.
If you want to persist with what you have, ensure both ends of adapter have a good seal this can be improved by applying a little grease to the threads and O rings.
After opening the screw tops of the valves tap them so a little air escapes to ensure they are not stuck.
Be careful not to push the adaptor too far on to the valve in case it may be holding it open.

abcdggs

I wouldn't agree with the petrol station pump being too powerful, car tyres aren't ever inflated to as high a pressure as bike tyres. Would definitely agree with the rest of it though

Nietzschean

abcdggs wrote: »

I wouldn't agree with the petrol station pump being too powerful, car tyres aren't ever inflated to as high a pressure as bike tyres. Would definitely agree with the rest of it though

they don't use the same pressure in the tyre, but the pressure in the pump can be up around 300psi so that it can fill a car tyre faster...

abcdggs

:eek:

suitably corrected, i'd also suggest getting a track pump

victorcarrera

abcdggs wrote: »

I wouldn't agree with the petrol station pump being too powerful, car tyres aren't ever inflated to as high a pressure as bike tyres. Would definitely agree with the rest of it though

Petrol station compressors are designed not just for low pressure car tyres but are also capapable of inflating HGVs tyres (80-120psi typically and some construction/agricultural vehicles up to 200psi).
The problem is that the volume required to fill a small bicycle tube only takes a fraction of a second from a (15 bar 210psi) compressor.This can send your tube from 0 to bang and back to 0 before you know it.
There is also the real possibility of the valve or adaptor blowing off and causing injury.

clubberlang

rowanh wrote: »

Hi, i got an adapter for the small bike tyrevalves yesterday but when i tried to inflate them in a petrol station it didnt really work, one seemed to get a bit harder but not much and the other not at all, the pressure was coming up around 40 psi. I went to another petrol station, i noticed there that you have to unswrew the valves, one was already unswred which is why it was working a bit. I still couldnt get the pressure to go about 50 or 60, it seemed like when it was on 60 i would put air in it then it would drop down to 50 or lower. Im wondering am i doing something wrong or it the adapter not working or maybe there is someone wrong with the valves? It did kind of look like the distance from the thing inside the pump that pushes the vavle in was farther away than the valve pin in the adapter but hard to tell really. Any ideas would be much appreciated.

Rowan

I had the same problem with my first presta tyre experience:) I tried using an air compressor but couldnt get it to much more than 50 psi. I also had a small hand pump which will pump to about 80-90 psi, I carry this with me on spins in case I get a puncture, it would be good enough to get me back home if needed. I bought a track pump from chain reaction cycles for €25 and its the business, no problem getting the required 110 psi definatly a good investment.

blorg

victorcarrera wrote: »

The problem is that the volume required to fill a small bicycle tube only takes a fraction of a second from a (15 bar 210psi) compressor.This can send your tube from 0 to bang and back to 0 before you know it.
There is also the real possibility of the valve or adaptor blowing off and causing injury.

I have been inflating from petrol stations for years and have never had a problem. You need to do it in short bursts, but I think the risk is over-stated if you are even half-way careful.

I wouldn't do this as my primary or only way of inflating (I use a track pump) but it is useful to get back up to a reasonable pressure if you puncture without CO2, or indeed touring.

Thargor

Theres a nice footpump for a fiver in the Lidl cycling offers this week, saw a few in Galway this morning.

blorg

I have a footpump from Lidl which was utterly useless for bike inflation, FWIW.

tomasrojo

If you're stuck, a forecourt pump is ok. But if you cycle a lot, you might as well buy a track pump. There's no downside to owning one: they store easily, they're accurate and pump the tyre up to the desired pressure very quickly with very low risk of exploding the tube. And they're not terribly expensive either.

Highway_To_Hell

blorg wrote: »

I have a footpump from Lidl which was utterly useless for bike inflation, FWIW.

+ 1, also got a small hand pump which is useless as well. Spend the money (€40) on a decent track pump it really makes life easier when it comes to tyre inflation, works well for any rugby, foot or basket balls that need inflation as well.

tomasrojo

rowanh wrote: »

Hi, i got an adapter for the small bike tyrevalves yesterday but when i tried to inflate them in a petrol station it didnt really work, [...] the pressure was coming up around 40 psi. [...] Im wondering am i doing something wrong

Yes, you're using imperial units. Metric, ftw!

rowanh

Thanks for the advice, sounds like a foot pump would be worth getting though i never had any trouble inflating my previous bikes tyres in petrol stations. I think i might pop into the guy who sold me the adapter and ask him what he thinks. Im just a bit worried about getting a puncture from the tyres not having enough pressure.

blorg

It depends on the type of bike. You cannot accurately inflate road bike tyres with a petrol station pump. Mountain bike/hybrid tyres accuracy is not so critical and you can get it OK. Note you do NOT want a "foot" pump, you want a "track pump."

abcdggs

rather than a foot pump, i'd suggest something like this, very accurate and easy to use