Pumping presta tubes in the petrol station with adaptor to 120psi.

rubadub

I have an adaptor for presta tubes so they can be pumped at a petrol station i.e. with a shraeder adaptor. I remember doing this with a foot pump too and I dont think the pressure showing was correct. I want to go to 120psi, I think it only registers while pumping and closes when not pumping, sort of opposite to how a car tube would work.

Is there any trick to doing this? I dont want them to explode!

blorg

I pump mine up that way although don't pay attention to the gauge, it doesn't seem to provide a lot of usable information.

I'm afraid I use the highly unscientific press finger against tyre test, have yet to suffer an explosion though.

This is on 700x23s (road bike) and 700x28s (tourer.)

crashoveroid

First rule is never use a petrol pump air station
1 you cab damage the tyre
2 you can split the rim

use only a track pump they dont cost much about €20.00 upwards

Morgan

Wouldn't your tube blow out well before your rim splits? Surely you only risk damage to your tyre/tube if you wildly overinflate the tyre - something which can be avoided using a modicum of care.

blorg

crashoveroid wrote:

First rule is never use a petrol pump air station
1 you cab damage the tyre
2 you can split the rim

use only a track pump they dont cost much about €20.00 upwards

Personally I would be filing this under "never use a tyre iron to put back on a tyre," I have been pumping at petrol stations for over a decade without a single problem.

This is not to negate the usefulness of a track pump BTW.

Stereophonic

Track pumps are very accurate if you spend €40 for one and upwards. Some of my local petrol stations prohibit cyclists from using the air compressor.

John_C

I've always found it very difficult to get tyres up to full pressure by this method. The air tends to leak out the sides of the adapter above about 3 or 4 bar.

crashoveroid

Morgan wrote:

Wouldn't your tube blow out well before your rim splits? Surely you only risk damage to your tyre/tube if you wildly overinflate the tyre - something which can be avoided using a modicum of care.

No The tube may not blow i have seen rims split from doing this . Dont forget Air pumps are designed for cars and not for racing wheels

el tel

Remember bike tyres are low volume, high pressure
Car tyres are high volume, low pressure

Personally I strongly advise against using a forecourt pump - get a track pump, do it properly and not be dependant on a garage.

rubadub

I'm afraid I use the highly unscientific press finger against tyre test, have yet to suffer an explosion though.

I do not know how hard it should feel.
I will be getting a track pump soon though, I might not have bothered if there was a good way of doing it in a station though.

Danbo!

Stereophonic wrote:

Some of my local petrol stations prohibit cyclists from using the air compressor.

I used to work in a petrol station, the sign says no cycles or inflatables as a disclaimer in case some kid blows is face off pumping up his bike tyres. generally most staff are ok with it.

cyclopath2001

rubadub wrote:

I want to go to 120psi,

I think 120 is too much, what are your tyres rated for? Even if 120 can be handled, I think 100 is enough.

Capt'n Midnight

Morgan wrote:

Wouldn't your tube blow out well before your rim splits? Surely you only risk damage to your tyre/tube if you wildly overinflate the tyre - something which can be avoided using a modicum of care.

yes it happens
if you had V brakes you could have damaged the rim already

the problem with garage pumps is the volume - the difference between just right and overinflated is a tiny time

rubadub

cyclopath2001 wrote:

I think 120 is too much, what are your tyres rated for? Even if 120 can be handled, I think 100 is enough.

It is only 116psi max (though I know there is a large factor of safety in tyres). I was really just throwing a high number out there. What probs do you find at 120?

Also how soon after they are at 100 do you have to pump again? e.g. if 120psi are they down to 100psi after a month?
Probably depends on a few factors

crashoveroid

cyclopath2001 wrote:

I think 120 is too much, what are your tyres rated for? Even if 120 can be handled, I think 100 is enough.

The problem here is people are unsure of a few things
1) your tyres has set pressure it can go to
I have tyres that can go to 145psi

2)your rim has a set pressure to go to before it splits
Most Rims are about 120psi

3)The rule is if its clincher 120psi should be enough if you want more please get a tubs and you can go all the way to 180psi

4)100psi is not enough at that pressure you need to use more energy to pedal

pete4130

I've used garage pumps, track pumps, hand pumps on a variety of bikes I have from BMX (anything from 60psi to 120psi) to track bikes, road bikes and comfort bikes. The adaptors don't allow you to get an accurate readin gof the pressure. From experience I can tell if my tires are over or underinflated. You do have to be careful with garage pumps as someone else mentioned bike tyres are low volume/high pressure tyres and get to a high pressure very quickly. Just make sure that the tire is properly on the rim before you start inflating. The last thing you want is for the beading of the tire not be properly secured on the rim and creep out to blow the tube. I've never personally experience rims being damaged (not to say that it doesn't happen). My biggest piece of advice on using garag epumps would be to use short, sharp bursts and to check the tyre after each burst to get a feel for how hard it is.

Track pumps are very good and even reasonably cheap ones from Argos for about €15 will do the job but wouldn't be all that accurate (usually about 20psi lower than they say they are at).

You can buy cheap pressure guages for as little as €3-€5 in bike shops that you simply place over your valve and they give you an accurate reading of your tyre pressure.

Ghost Rider

Good to know. But would such gauges necessarily be any more accurate than the one on your average track pump?

pete4130 wrote:

You can buy cheap pressure guages for as little as €3-€5 in bike shops that you simply place over your valve and they give you an accurate reading of your tyre pressure.

ruprect

pete4130 wrote:

Track pumps are very good and even reasonably cheap ones from Argos for about €15 will do the job but wouldn't be all that accurate (usually about 20psi lower than they say they are at).

I got the argos one, went outside the shop to pump the bike and was back inside 2 minutes later getting my money back!

Only went to 75psi and was leaking. Then just wouldnt go higher even though air was going in. My tyre got damaged, not sure if it was overpressured, didnt feel it, think it was worn at the bead from taking on and off, and deteriorated in the wet.

Argos have a "extra" model, mine was the normal one on sale.

I am waiting to hear the post costs on this
http://www.kudubikes.co.uk/cgi-bin/trolleyed_public.cgi?action=showprod_BBBAIRWAVE

It is £20 on www.chainreactioncycles.com . They refused to honour the price match on CRC, gets good reviews there though.

daymobrew

I have and love the Topeak Master Blaster Mini Pump. Has a guage, goes to 120psi, is small and has a frame mount. Less than 18 euro.

cyclopath2001

rubadub wrote:

I was really just throwing a high number out there. What probs do you find at 120?

My tyres are rated for 100-125, so it's a matter of personal preference. Since I ride it around town, I prefer a bit of extra grip.

crashoveroid

daymobrew wrote:

I have and love the Topeak Master Blaster Mini Pump. Has a guage, goes to 120psi, is small and has a frame mount. Less than 18 euro.

These pumps are only at the side of the road jobs and not meant to replace a Track pump and why have the trouble at the side of the Road get yourself a Co2 Pump they are the job and no effort involved

blorg

A lot of bike shops seem to use compressed air systems that look suspiciously like those found in petrol stations. Are they different?

Stereophonic

Those little pumps require a good deal of effort in my opinion. There only to get you home really if you have a puncture.