Bicycle Mechanics - Presta Valve Adaptor and Air Compressor problem

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gholt
08-03-10, 11:01 AM
I have read all the threads on the Presta and air compressors. I'm going to buy the following:

http://www.biketoolsetc.com/index.cgi?id=92531081272&d=single&c=Tools&sc=Tire-and-Tube&tc=Valve-Adaptors&item_id=SI-2220

or

http://www.amazon.com/Prestacycle-Prestaflator-Replacement-Presta-Color/dp/B003GAR8HO/ref=sr_1_57?ie=UTF8&s=sporting-goods&qid=1279395278&sr=1-57

Someone in the family broke my floor pump. No one is fessing up. Everyone know how that goes. I have ordered a new pump, but I would like to get a backup for when the floor pump is not working. I'm also going to see if I can repair the pump to have as a backup.

But, I still have a question for all the experts out there. I have one of the schrader / presta adaptors. I have put the adaptors on as snug as I can and the Orinig is sealed, and I can't get the air to start out of the schrader chuck.

It looks like the pin in the middle of the scrader chuck is not getting depressed so that the air isn't released, and when I look at the presta pin. It is so far in the tool that it does not even come close to touching the schrader valve (This is probably not the issue). I have three different adaptors, and not one of them work with my shcrader chuck. It works fine for all the schrader tubes though.

So, does anyone know of a chuck you can use that will allow the air to open up to put air in the presta valve with the adaptor. Some gas stations work for this, but I don't want to pay $ for 2 minutes of air to repair my tires. i have about 5 and it is a big pain.


blamp28
08-03-10, 01:13 PM
For what it's worth, I have a compressor at home and have never used it for bike tires in 20 years of repairing bikes for my family of 9. I'm not against it it just seems like too much trouble to fire it up to top off or fill the occaisional tire. I fill up my tires before every ride so that is 5 or 6 times per week and it would take almost as much time to fire up the compressor, wait for it to reach pressure and put on the adapter (my bikes all use presta) than to just hook up the floor pump and pump up the tire.

fietsbob
08-03-10, 01:29 PM
Prescribe a proper hand pump such as these : http://www.sjscycles.co.uk/product-Silca-Silca-Pista-Floor-Pump-23388.htm

It's a Presta Pump head, NB: there is a plain band on all presta stems its between the coarse thread for the cap and the fine thread for the ring-nut, that is where the pimp head gasket seals .

then Get another pump for the Schrader stuff for Utility, Schrader,
the rest of the family's use..


Shimagnolo
08-03-10, 01:30 PM
For what it's worth, I have a compressor at home and have never used it for bike tires in 20 years of repairing bikes for my family of 9. I'm not against it it just seems like too much trouble to fire it up to top off or fill the occaisional tire. I fill up my tires before every ride so that is 5 or 6 times per week and it would take almost as much time to fire up the compressor, wait for it to reach pressure and put on the adapter (my bikes all use presta) than to just hook up the floor pump and pump up the tire.

The problem is the air tank.
The tank is there only for the purpose of smoothing the pressure spikes for air tools.
It is pointless for inflating tires.

Here is a tankless compressor that works like a charm: http://www.amazon.com/Black-Decker-ASI300-Station-Inflator/dp/B000IE0YIQ
Set the pressure; Turn it on; It shuts off when it reaches the pressure setting.

FBinNY
08-03-10, 01:32 PM
Schrader chucks require that the tire's valve depress a pin in the chuck to get the air flowing. On Schrader valves that's no problem since the pin is close to flush with the top of the valve, and when ypou press on the chuck, both valves open.

With Presta valves and an O-ring adapter you need to duplicate a similar fit. Most adapters are a bit too long, so the valve stem doesn't reach, or with a fully deflated tube doesn't offer enough resistance. File the adapter close to flush with the valve stem, and open the nut only half way so the valve stem doesn't drop down so far and you'll be fine.

gholt
08-03-10, 01:35 PM
I never thought of that. That is a cool idea.

I will file it off tonight. Thanks for the input.

fietsbob
08-03-10, 01:41 PM
FWIW if the airpressure is higher than the spring that closes the schrader core + the air in the tire is higher than the pump provides the valve will open , ,But Presta is not spring loaded so loosening the lock nut on the stem and tapping it to break the stickyness on the seat will get you pumpimng ,

The one You show via Amazon, is kind of like the Silca accessory Head,
the other one is un needed if you have a Schrader Pump. thumb lock Schrader pump head is better than one that screws on to the stem.

gholt
08-03-10, 02:07 PM
FWIW if the airpressure is higher than the spring that closes the schrader core + the air in the tire is higher than the pump provides the valve will open , ,But Presta is not spring loaded so loosening the lock nut on the stem and tapping it to break the stickyness on the seat will get you pumpimng ,

The one You show via Amazon, is kind of like the Silca accessory Head,
the other one is un needed if you have a Schrader Pump. thumb lock Schrader pump head is better than one that screws on to the stem.

So, the schrader is brand new. So, tapping it may make the pressure release. I have also set the compressor hose to 120 psi, should i lower it to about 30 or 40 and then raise it up once I can get the spring to release?

Al1943
08-03-10, 02:18 PM
So, the schrader is brand. So, tapping it may make the pressure release. I have also set the compressor hose to 120 psi, should i lower it to about 30 or 40 and then raise it up once I can get the spring to release?

You don't need to tap a schrader valve, that's the kind used on cars and some bicycles. Presta valves often stick closed and need to be "burped" before inflation. Check the pressure values on the side of the tires. If the load on the bike is not too heavy you can ride at about 10% below maximum recommended pressure. For heavier loads go to near maximum.

wunderkind
08-03-10, 02:21 PM
The compressor that I use to air up the bike tires connects to the 12V power outlet from my car. Works great. :thumb:

desconhecido
08-03-10, 02:23 PM
It is typically not necessary for the valve in a Shrader valve to press open the valve on an air chuck. Indeed, in almost all cases -- every case I have ever tried, you can get the air chuck to operate even when the valve has been removed from the Shrader stem. Watch someone install auto or truck tires and you will believe me. What presses against the valve in the air chuck and opens it is the barrel of the Shrader valve stem. The Shrader valve stem is a standard inside and outside diameter and air chucks are made so that the barrel will open the valve on the air chuck. The problem with some air chucks and with some Shrader adapters (and some valve stem extenders for truck wheels and the like) is that if the inside diameter of the adapter is slightly larger than a standard Shrader stem, it will not open the valve in some air chucks. In my experience, the angled dual head Milton brand air chucks are the most likely to work. Here's a pick of the one I mean:163059

roberth33tiger
08-03-10, 02:25 PM
i put one of these on my B&D compressor
http://www.niagaracycle.com/product_info.php?products_id=428861

gholt
08-03-10, 02:32 PM
It is typically not necessary for the valve in a Shrader valve to press open the valve on an air chuck. Indeed, in almost all cases -- every case I have ever tried, you can get the air chuck to operate even when the valve has been removed from the Shrader stem. Watch someone install auto or truck tires and you will believe me. What presses against the valve in the air chuck and opens it is the barrel of the Shrader valve stem. The Shrader valve stem is a standard inside and outside diameter and air chucks are made so that the barrel will open the valve on the air chuck. The problem with some air chucks and with some Shrader adapters (and some valve stem extenders for truck wheels and the like) is that if the inside diameter of the adapter is slightly larger than a standard Shrader stem, it will not open the valve in some air chucks. In my experience, the angled dual head Milton brand air chucks are the most likely to work. Here's a pick of the one I mean:163059

The one I bought last night was in the Husky from Home Depot. That could explain why I there was such a big gap in ghe schrader chuck and the adaptor.

Grand Bois
08-03-10, 03:10 PM
Schrader chucks require that the tire's valve depress a pin in the chuck to get the air flowing. On Schrader valves that's no problem since the pin is close to flush with the top of the valve, and when ypou press on the chuck, both valves open.

With Presta valves and an O-ring adapter you need to duplicate a similar fit. Most adapters are a bit too long, so the valve stem doesn't reach, or with a fully deflated tube doesn't offer enough resistance. File the adapter close to flush with the valve stem, and open the nut only half way so the valve stem doesn't drop down so far and you'll be fine.

Wrong. That's not how they work at all. The post above is correct.

Burp the Presta valve.

gholt
08-03-10, 03:18 PM
How do you burp them if the tubes are flat?

skilsaw
08-03-10, 03:29 PM
Buy a new bike that has properly inflated tires.

gholt
08-03-10, 03:31 PM
Buy a new bike that has properly inflated tires.

LOL

I think at 2AM this morning, I would have been at that point.

Grand Bois
08-03-10, 04:26 PM
How do you burp them if the tubes are flat?

It doesn't matter. The valves stick. Unscrew it and press down to unstick it.

I always use a compressor, but I use this. An angled chuck would have been better, but it works.

http://inlinethumb30.webshots.com/46301/2312977780068014369S600x600Q85.jpg (http://sports.webshots.com/photo/2312977780068014369wccxcP)

FBinNY
08-03-10, 04:59 PM
Wrong. That's not how they work at all. The post above is correct.

Burp the Presta valve.

If it were the, OP wouldn't have had a reason to post in the first place.

On all SV chucks, you depress the pin to start the flow, plain and simple. Most chuck pins are conical and a bit wider so they'll be pressed open by the wall of the (Schrader) valve, or adapter, and not depend on the height of the pin as in the referenced post, but that doesn't help the OP because many PV adapters are bored open and have IDs too large to engage the chuck's pin and depress it.

If the OP uses either a shorter, or thicker walled adapter all will be OK. If the heights are matched he also won't need to burp the valve to top off a full tire because the chuck's pin will exert enough force, but with a tall thick walled adapter he might need to.

dedhed
08-03-10, 05:06 PM
You don't need a valve core in a Schraeder valve to operate the chuck. I've seated lots of auto tire beads without having the core in reducing the volume needed.
Either something is wrong with your new chuck or the adapter.

gholt
08-03-10, 05:50 PM
It doesn't matter. The valves stick. Unscrew it and press down to unstick it.

I always use a compressor, but I use this. An angled chuck would have been better, but it works.

http://inlinethumb30.webshots.com/46301/2312977780068014369S600x600Q85.jpg (http://sports.webshots.com/photo/2312977780068014369wccxcP)

Is that a presta attachment, if so, where did you get it. Also, the verdict is in. I filed down the adaptor and it works like a charm. I guess I got a little bit too happy with the grinder and I filed the 1st one down too far. But it works enough to get 120 psi in the tire.

gholt
08-03-10, 06:04 PM
Here is a pic of the two that I ground down. the one on the left I got too short. I got a little happy with the grinder, but it still works. The one on the right, I think is the right height for my pump and I think for most pumps around.

wrk101
08-03-10, 06:12 PM
+10 Burp the valve first. I air up tires all the time using my 6HP shop compressor. And I only use presta valves. Works fine. The only thing you have to watch is that the bead seats properly, as the tire fills fast.

Grand Bois
08-03-10, 06:22 PM
Is that a presta attachment, if so, where did you get it. Also, the verdict is in. I filed down the adaptor and it works like a charm. I guess I got a little bit too happy with the grinder and I filed the 1st one down too far. But it works enough to get 120 psi in the tire.

A cheap tire inflator, a Silca barbed fitting and a hose clamp.