have never pumped a tire properly. HELP

To all those who felt bad because they have trouble pumping up their tires and need to lift their feet off the ground to apply enough weight on their floor pump, think about this:

(And keep in mind that I'm not very good at physics. But I hope this makes sense.)

Think about how a bike pump works. You need to compress the air that's in the pump to the point where you build more pressure in the shaft of the pump than there already is in the tube, so that the air in the pump needs to "escape" in the tire. Let's say you're pumping your tires to 100 psi (Pound per Square Inch) and let's imagine that the surface of the bottom of your pump is 1 square inch (in fact it's probably a bit bigger than that), you need to push increasingly close to 100 pounds down as you approach 100 psi on the gauge, in order to push the volume of air that's in the pump into the tire.

For us petite women with not a whole lot of upper-body strength and not a lot of weight, it's almost as much as we our own weight!

Start doing those push ups.

First, around here we just don't get crabby when someone asks a how-to-do-it question. We all have those. This is the place one goes to get legitimate questions answered. What is more legitimate than getting air in the tires?

Second, I really don't have much to add, but I agree that the pump could easily be bad - after all you were successful with another pump, right? - or the physics of the matter might be defeating you - you said you are small, right?

Me, I'd take the advice and get my bike and the pump to the LBS. If the pump is the culprit, toss the thing right there and get one that works. Test the very pump you are planning to buy right there in the store. Don't take home one that fights you.

Finally, once you get the pumping tires thing straightened out (and you WILL), and have more questions, come back here and ask. Please. We live but to serve.

Quote:

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Originally Posted by Eden

The pump you are using can make a huge, huge difference - and its not necessarily that the more expensive the pump the better.... we had a fancy, schmancy Italian Silca that I hated with a passion. It was fickle and took 3 hands and more than my entire body weight to operate. We have a Joe Blow now and other than the little rubber gasket on the head really needing replacing it is great - I can even get my TT bike tires up to 140 psi without having just pumping up the tires being an adequate warm up....

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Hey it seems that we have the same pumps and the same feelings about both of them. The Silca only gets used by my husband I hate it. My problem with this pump is that once it is attached I can never seem to get it off. If I don't push it on as hard air comes out when I pump. It is just so much easier to use the Joe Blow with the lever then I have no disconnecting issues.:o

I also had trouble pumping at first. One thing that's helped me is position of the valve. I like it to be right at the floor, that way I get gravity helping lock the pump onto the stem.

Also, try unscrewing the valve nut a little less, not all the way open, and see if that helps.

I just bought an air support mini pump. I can't find any instructions on how to mount it or a picture. Is it suppose to go on the water bottle cage? I would appreciate any help.

Thanks
Robin

Quote:

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Originally Posted by redrhodie

I like it to be right at the floor, that way I get gravity helping lock the pump onto the stem.

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I like it to be at the top :p and I think that's actually where most people pump. You get the straightest run from the hose, so you're less likely to be fighting that resistance. But maybe it's just a hold-over from pumps without latches, like the Silca pump, where pumping with the valve at the top allowed you to hold it until a good seal was established.

Either way, top or bottom, probably minimizes the chance of damaging the valve stem, because you have a clean push-pull to put the pump head on and take it off.

I put the valve at about 10 o'clock to get the pump head pushed securely on there with my right hand.
I have had some that seem to never quite get the valve engaged, and I've spent 30+minutes just letting air out of my tire. It's the pump, not my IQ.

As for getting tires up to road tire pressure, a taller/larger and rigid barrel to the pump will help make it easier than using a short plastic kid's size pump.

Quote:

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Originally Posted by robinmarylong

I just bought an air support mini pump. I can't find any instructions on how to mount it or a picture. Is it suppose to go on the water bottle cage? I would appreciate any help.

Thanks
Robin

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I'd suggest starting a different thread with your question, with some more information about your pump. And welcome to TE! Please think about introducing yourself in the "Getting to know you" thread. :)

I'm 130 lbs and pump my road tires to 100 psi, max. 90 or 80 would be fine as long as I am paying attention to the crud on the road and my tires are in good shape. No need to go super high with psi if you are fairly light. That is for the big boys, or if you are trying to get the ultimate advantage in a race. A slightly softer tire makes a big difference in the comfort of your ride, and no damage results as long as you check the tire's psi frequently (i.e., don't let it get low).

The advice to press on the valve and let the valve open and a bit of air escape before pumping them up is very good. Also, orienting the valve so it is at 7 to 11 o-clock makes the pump happier and more likely to "seal." That is, the head of the pump shouldn't be at an awkward angle or be fighting the resistance of the hose when you attach it. This has all been said... And I find keeping my arms straight and using my whole upper body instead of just my arms to pump up tires really makes it quite do-able. I pump up a lot of tires and my pump ain't fancy...it costs about $40 retail.

OK, what role does stem length have?

• I find that shorter stems are much easier to attach and remove the pump from
• But the LBS says "no, no no....long stems are best!"

Why? do they enjoy:

• The bloody knuckles that result from getting banged on the cassette or sharp aero spokes as you struggle to pull the pump off the longer stem?
• Selling more tubes because of the inevitable leaks that result from pulling so hard on the stems to extract the pump (and most of my flats come from slow leaks immediately around the stems...)?

They never have the short stems in stock...:mad:

Am I alone in this observation on stem size????

That's weird, the smaller LBS's in my area normally stock only the 48 mm stems, the larger ones have all lengths in stock. I've never had them push me toward a longer stem. I agree that 38 mm stems are getting harder to find, but that's only because the shallowest rims are getting harder to find!

I'm guessing that your LBS has had experiences where people have bought tubes with stems that were too short for their rims, then blamed the LBS when they got stuck with a flat tire in the middle of nowhere. If they sell everyone 60 mm stems, then at least everyone will be able to use the tubes they bought.

I've been on a ride with someone who forgot to swap his spare tube out after switching to deep aero rims - and just the other day someone here posted that her DH had stocked her seat pack with the wrong tube.

I'm with you that it's best to use the shortest stem length that will work with your rim and pump head (different pumps grab different lengths of valve stem). Lighter, less angular torque on the valve stem if you aren't completely smooth with the pump. But if someone doesn't know what stem length she needs, I can definitely see the bike shop just selling them 60 mm and being done with it.

Another observation, do road bikes lose pressure in the tyres faster than mtb? Both my bikes have presta valves, the mtb gets a top up every couple of weeks (and is used regularly during the week for communting), the road bike seems to lose about 20-30 psi in a week, even when not used. They are the stock tubes it came with and it did this before I even went on my first ride, so definitely no punctures...

the more pressure you put into a tube, the faster it's going to figure out how to get out.
If your MTB tire is at 50psi and your Road bike tire is at 150psi, there will be a dramatic diff. as to how much air is lost in time.

That's part of why i think you gals should check to see if you aren't overinflating the tires for your weight specs.

and my DH taught me a cool trick. make sure the valve is at the TOP of the wheel when you attach it to the pump. SO when you are ready to stop and pull it off you are pulling/pushing DOWN; so it's easier.

The mtb is mainly ridden on the road, so the tyres are semi-slicks run at 70psi...the roadie is between 100 - 110, which seems to work fine (apart from losing air rather quickly). I weigh about 65-67kg, so maybe I could get away with a bit less, but I'm a bit worried about pinch flats, etc.