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-   -   Is there a trick to using Presta adapters? (https://www.bikeforums.net/general-cycling-discussion/1155982-there-trick-using-presta-adapters.html)

no motor? 09-20-18 02:24 PM

Is there a trick to using Presta adapters?
 
I used my Topek Joe Blow floor pump to inflate both tires (using Scchrader valves) on my bike to 80 psi yesterday without a problem. I used the same pump on the front tire of my girlfriends bike to the same 80 psi using the Presta adapter that was on the bike when she bought it, something I've done before. No real problem there beyond needing to put more air in her tires than mine. When I tried to do the same thing in the back I couldn't get more than 60 psi in with pumping like a madman, easily pumping 2 - 3 times more air than I did for the front tire. When I stopped to rest the pressure dropped to 20 psi. This happened a couple of times until we quickly removed the air hose when we got to 60 psi, and the tire seemed to retain that air after we were finally able to ride instead of pump even more air into the rear tire. I've used these same adapters on the same tires for a couple of years and have never had this much trouble, what was wrong? Neither one of us could hear any air leaking out, and nothing seemed wrong beyond the problems I already mentioned.

fietsbob 09-20-18 02:48 PM

schrader adapters on presta tubes? the stem is a check valve, so air goes in opens the check valve,
you hear air leaking out of the hose ,

but the valve in the tube stem shuts

if the hose pressure drops below the pressure in the tube..

there are adapters with O rings, they may seal better.

Silca , Italy , made an adapter to screw on your Schrader valve and use a presta pump..

convert to woods /dunlop valve tubes ? Schwalbe makes Those , too .. same rim stem hole as schrader

https://en.wikipedia.org/wiki/Dunlop_valve .../



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Maelochs 09-21-18 05:38 AM

I used to use Schrader adapters on Presta valves for a long while. There is a tiny rubber o-ring inside the Schrader adapter, and as soon as that o-ring falls out (and it can if you aren't careful removing the adapter. if you do lose the o-ring the air will leak out almost as fast as it goes in.

If that's not it .... maybe you damaged the Presta valve while screwing on the Schrader adapter.

trailangel 09-21-18 07:39 AM

I don't know what a Presta adaptor is. And, you don't need any kind of adapter with a Joe Blow pump, works with Schrader and Presta without any adapters... so what are you doing?

WizardOfBoz 09-21-18 08:04 AM

Check the o-ring as Maelochs suggests. If that's ok, it could be that you put the adapter on correctly, but the air hose was mashed too tightly up against the adapter and was holding the core in a position that was just open a little. Hard to pump into, and leaks out. Put the adapter on and experiment with how you hook up the pump head to the adapter.

Or, if your pump is the model that trailangel is thinking of, use the Schrader Presta port on the pump head directly.

I had an issue with tubeless where the stem had clogged with sealer. Tried to pump into the tire without realizing this and blew up the hose on my pump.

tagaproject6 09-21-18 08:43 AM


Originally Posted by trailangel (Post 20578093)
IAnd, you don't need any kind of adapter with a Joe Blow pump, works with Schrader and Presta without any adapters... so what are you doing?

This!

no motor? 09-21-18 10:31 AM


Originally Posted by trailangel (Post 20578093)
I don't know what a Presta adaptor is. And, you don't need any kind of adapter with a Joe Blow pump, works with Schrader and Presta without any adapters... so what are you doing?

This is a Presta adapter. https://www.amazon.com/Vktech-Converter-Schrader-Bicycle-Adaptor/dp/B00DW444C6?ref_=fsclp_pl_dp_4 It allows you to inflate a tire using a Presta valve using a Schrader head on the pump. I was attempting to use the pump to increase the pressure of the gasses inside the tube relative to the gasses outside the tube.

fietsbob 09-21-18 04:04 PM

Get this one, keep it with your S/V pump..
the top (hose barbed) end screws off,
that is schrader thread..
https://www.ebay.com/itm/232877142889

https://i.ebayimg.com/images/g/h6kAA...di/s-l1600.jpg

Maelochs 09-21-18 04:25 PM

As a few folks noted above ... most pumps nowadays have reversible or convertible chucks, so you can adapt the pump to the valve. Does yours?

no motor? 09-25-18 10:45 AM


Originally Posted by Maelochs (Post 20579105)
As a few folks noted above ... most pumps nowadays have reversible or convertible chucks, so you can adapt the pump to the valve. Does yours?

The one I have at home does, the one I left at her house had an adapter on the chuck that is a good 25 years old. I'd rather she use the adapters on the wheels if she inflates her own tires and wanted to make sure this is still possible.

rosefarts 09-25-18 11:05 AM

I remove the o-ring from my presta valve adapters. The ring is too tight and more times than not, will screw the valve closed when screwing the adapter onto the valve.

It doesn't leak at all.

Of course the only time I use it is to seat beads on tubeless tires. My 20 year old floor pump has both valve types. Even Walmart pumps have both.

Once presta chucks for an air compressor drop under $40, adapters will be obsolete for me.

MattTheHat 09-25-18 11:30 AM

I keep a Presta adapter in my saddle bag in case I have to inflate a tire at a corn-venience store. And I used them for a couple of weeks before I found a Presta air chuck for my garage compressor. Sometimes they thread right on and sometimes they don't. I found a slightly bent Presta core was the problem. I guess it's possible that a slight misalignment could cause the Presta core to leak a bit but it sure seems like you would have heard it.

-Matt


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