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shadon
05-06-2006, 10:18 PM
This seems like it should be so basic...but....it's not.

In prep for my ride tommorow...I went to check and fill my tires...back tire no problem. Front tire...not so much. I attached the pump to the valve and it seemed instead to remove air from the tire...suffice to say I now have a front tire that is to soft to ride and has less air in it than it started with.

What the h*ll am I doing wrong???

DirtDiva
05-07-2006, 03:07 AM
I dunno. I've bent one of the Presta valves on my bike and I have to be quite careful when I fill that tyre. Mostly it's a problem when I'm trying to get the thing screwed back up fully though... :confused: Hope you can get it sorted ASAP.

shadon
05-07-2006, 12:44 PM
of course I go off to the closest LBS...and it filled right up. and got the typical bike shop dude shrug..."I dunno..maybe it's your pump" as she (yes she) walked away.
So no I need to salvage the day with some sort of ride...ggrrrrr

Running Mommy
05-07-2006, 01:25 PM
It may be your pump! IF you have a pump that has a head for both presta and schraeder valves, it may be the pump. Occasionaly my pump will not recognize that I just inserted a presta valve, and it blows air out the other side! :mad:
I thought I was nuts until my husband had the same problem with it. I guess there is a little mechanism inside that doesn't always work?? Because it does it every once in awhile, but for the most part it works. Frustrating for sure!
I could see where it seems like it's taking air out because the pump is pressing on the valve and so air is being released.
Anyway, that's my best guess. Sorry- no real "answer" for you! :confused:

Geonz
05-07-2006, 03:31 PM
It makes a difference on my bike where the valve is. If it's down between 5 and 7 o'clock, I can't seem to get it to work. I'd have thought pointing down owuld be best... but 11 or 1:00 work best. Getting just the right angle seems to be the trick. (I have the same issues a little bit with the car tires... but my plan is to take them in tomorrow ...)

shadon
05-07-2006, 06:56 PM
It may be your pump! IF you have a pump that has a head for both presta and schraeder valves, it may be the pump. Occasionaly my pump will not recognize that I just inserted a presta valve, and it blows air out the other side! :mad:
I thought I was nuts until my husband had the same problem with it. I guess there is a little mechanism inside that doesn't always work?? Because it does it every once in awhile, but for the most part it works. Frustrating for sure!
I could see where it seems like it's taking air out because the pump is pressing on the valve and so air is being released.
Anyway, that's my best guess. Sorry- no real "answer" for you! :confused:


Hmmmm...I think I'm gonna go find a presta specific pump then. I don't need agrevation like that...it completely through me off my grove for getting ready for the ALC...

Now to work on riding down hill.

mellic
05-07-2006, 08:18 PM
I would take Geonz advice before you buy a new pump. Turn your wheel so the valve is at the bottom and then try.

Geonz
05-08-2006, 10:15 AM
At the top! At the top! (Or wherever it hasn't been... but for me, the bottom was where it didn't work.)

bcipam
05-08-2006, 12:07 PM
When you attached the pump nozzle, did you set the "hold" lever? In otherwise, the nozzle goes on and you usually pull the lever up (or down depending on the pump) to latch the nozzle on adn hold in the air. If you don't air comes out.

Bella
05-09-2006, 08:43 PM
I also have a dual Schraeder/Presta pump and succeeded in deflating one perfectly good tire. It was nothing but a struggle to re-inflate. I haven't found the magic formula yet - but I dare say I don't feel like experimenting.

Dianyla
05-09-2006, 11:51 PM
I've also got the (notso)Smarthead pump that senses schrader vs. presta head. I found that if I don't push the presta valve in far enough it tends to just leak air out as I pump, eventually deflating the tire. I think those pumps work by assuming that a schrader valvestem will only go in about 1/4" inch and a presta will go in more like 3/8" or even more like 1/2".

Melody
05-10-2006, 06:25 AM
If any of you are really hating the head on your pump, I really recommend one of these:

http://www.competitivecyclist.com/za/CCY?PAGE=BUY_PRODUCT_STANDARD&PRODUCT.ID=1135&CATEGORY.ID=47&MODE=

It's a replacement head for a Silca pump (dual schrader/presta) and should fit any standard hose on a floor pump. To access the shrader portion, just unscrew the presta head.

My husband and I have had numerous problems with breaking valve stems, leaking heads, etc. etc. That all went away when we converted our pump to this head. :) There's also no lever to pull. To use, just slip the head on the stem and start pumping up the tire. :)

Mel

Trek1500
06-01-2006, 07:41 AM
Maybe a little off topic, but does anyone use a CO2 inflator? I have one, but haven't used it because I'm not sure how it works. Do you just release a little of the CO2?

DebW
06-01-2006, 08:29 AM
I've had the opposite problem with a few presta valves that got so sticky that I couldn't get air into the tire. I'd have to let some air out by hand just to free up the valve. And I agree with Geonz that if often matters where the valve is - the chuck needs to be straight with the valve, so try moving the valve or the pump around until it is. It may also be useful to unscrew the pump head, remove the rubber gasket, and oil it.

Bella
06-01-2006, 02:24 PM
Maybe a little off topic, but does anyone use a CO2 inflator? I have one, but haven't used it because I'm not sure how it works. Do you just release a little of the CO2?


I used it at home as practice and of course carry them with in case I flat out on the road. The ones with the shut off valve are great because you don't have to use the entire canister.

Because CO2 is cold, your tires will deflate by next day - don't be alarmed. Just refill by traditional pump.

maillotpois
06-01-2006, 02:50 PM
Because CO2 is cold, your tires will deflate by next day - don't be alarmed. Just refill by traditional pump.


I've never had a Co2-filled tire deflate any faster than a regular pump filled one. And CO2 is all I use on the road. Maybe you didn't get whatever it was that cased the flat fixed?

Reminds me of the Sheldon Brown/Carapace posting:

redmist wrote:
>
> As far as weight and efficiency go these seem to be the way to go vs. frame
> or mini pumps. Any drawbacks?

CO2 is heavier than air, you will make your bike heavy and slow if you
use it. Helium is lighter, the only way to go if you want speed and
safety.

If you are willing to live dangerously, Hydrogen is lighter and cheaper
than Helium, but don't smoke while riding your bike if you use
Hydrogen...

Carapace Completed Umber
Lakehurst, New Jersey

maillotpois
06-01-2006, 02:53 PM
When you attached the pump nozzle, did you set the "hold" lever? In otherwise, the nozzle goes on and you usually pull the lever up (or down depending on the pump) to latch the nozzle on adn hold in the air. If you don't air comes out.


This can be tricky to get right - and every pump is different. I'll bet this was what the problem was. Shadon, you're going to have to figure out how to get your pump locked onto the valve right.

Veronica
06-01-2006, 05:11 PM
Because CO2 is cold, your tires will deflate by next day - don't be alarmed. Just refill by traditional pump.

Have you actually had your tires deflate the next day after inflating them with CO2? Or is this something you heard from someone else?

I ask because that's never happened to me. I've had 3 or 4 flats and used CO2 cartridges to inflate. I actually went back to using a pump when I had a rash of flats a year or so ago. I didn't like adding to the landfill and when I got a flat both front and rear at the same time (lots of glass on multi-use path in a not good part of town) it seemed prudent to not rely on my limited number of cartridges.

Anyhow... I suspect there must have been some other reason they deflated.

V.

PS After the double flat, we found a new way to get to the transit center. :D

mtbdarby
06-02-2006, 01:56 PM
V - I just bought my first co2 stuff and the guy at lbs said the same thing - your tire will deflate the next day with co2. Maybe you've just been lucky or temp also plays a part???

DebW
06-02-2006, 04:39 PM
As you inflate a tire with a CO2 cartridge, the CO2 will chill through adiabatic expansion. But once the temperature of the CO2 in the tire has equilibrated with ambient, which would probably take less than an hour under most conditions and depending on the insulative ability of the tire and tube, the pressure in the tire shouldn't change. So I don't understand tire pressure dropping overnight if you got through another hour of your ride with good pressure. Anybody want to put a temperature probe in their tire after inflating with CO2?

DirtDiva
06-02-2006, 04:41 PM
The next day part seems a bit far-fetched - doesn't take very long for a gas to cool or heat to the surrounding temperature, and the pressures in a road tire wouldn't be significant enough to have any great affect on this. :confused:

(i.e. What Deb said, but with smaller words. :p)

maillotpois
06-09-2006, 05:48 PM
V - I just bought my first co2 stuff and the guy at lbs said the same thing - your tire will deflate the next day with co2. Maybe you've just been lucky or temp also plays a part???


That's really crazy - I have never heard of that happening and no one on my team has ever had this happen. My tires stay inflated for weeks with CO2 filling. I don't even need to top them off within a week's time.

Now if you are using latex tubes, your tires will deflate overnight.

maillotpois
06-09-2006, 05:49 PM
As you inflate a tire with a CO2 cartridge, the CO2 will chill through adiabatic expansion. But once the temperature of the CO2 in the tire has equilibrated with ambient, which would probably take less than an hour under most conditions and depending on the insulative ability of the tire and tube, the pressure in the tire shouldn't change. So I don't understand tire pressure dropping overnight if you got through another hour of your ride with good pressure. Anybody want to put a temperature probe in their tire after inflating with CO2?


And I'd bet it would take less time for the temp to get to ambient thorugh brake heating and rotation.

Petra
06-09-2006, 10:56 PM
just a few more thoughts:
if a tire is inflated with cold gas, and then warmed up, the gas pressure will increase (like leaving your bike in the hot car on a sunny day.... the tire will explode eventually). If you fill your tire with He (I hope no one was planning on this anyway....might also get a little costly) the He will diffuse through the tire walls really really fast... and this really doesnt help out on the road.
Petra

madisongrrl
06-10-2006, 12:46 PM
V - I just bought my first co2 stuff and the guy at lbs said the same thing - your tire will deflate the next day with co2. Maybe you've just been lucky or temp also plays a part???

I've had this happen to me a number of times (in 2004 I was getting 1-2 flats everytime I rode....crappy stock tires couldn't even handle 1000 miles). I get a flat on my road bike, change the tube and inflate with CO2. I ride home and all is well. The next day, that tire will be flat as a pancake. I pump it up and and I'm back at it again. I've never understood it.

Veronica
06-10-2006, 12:57 PM
I guess we have special CO2 in California then. :D

V.

SadieKate
06-10-2006, 05:12 PM
Remember you have to match the source of the CO2 to source of the tube. French air for your Michelin tubes, Italian for Torelli tubes, English for the Contis, etc..

Dogmama
06-10-2006, 07:35 PM
What if I have Conti tires & Michelin tubes? :confused: World War III underneath my saddle! :eek:

SadieKate
06-10-2006, 07:51 PM
We may have to call for a UN sanction and send in some peacekeepers.

Geonz
06-18-2006, 09:28 PM
I had never heard of that until here ... and then last week on the ride some of the guys were talking about it happening to them. They thought that CO2 went through the tire faster than regular air - the rule of thumb was that if you used CO2 you should always empty and refill with regular air when you get home.

I wanted to use helium last week to lighten up.

DebW
06-19-2006, 06:48 AM
Here's an explanation that actually might make sense, posted by Erik Lindeberg on cycleforums. In fact, if the solubility and diffusion rate are responsible, then we might expect that different tube compositions would affect the diffusion rate, and thus the widely disparate claims of CO2 leaking or not leaking could all be possible.

CO2 Inflators
> I've heard that
> since CO2 is a smaller molecule, tires lose air quicker.What has been
> people's experience with them? Viable alternative? Weight & reliability?
>
Small molecules e.g. helium, may diffuse faster than larger molecules
through some materials. The CO2 molecule is, however, larger than
the main constituents of air, oxygen and nitrogen, both with respect to
molecular weight and size. There are other properties,
though, that contribute to how fast the gas molecules
diffuses through the rubber, in particular how easy they
dissolve in rubber.