Presta valves constant failures.
 

Everyone hates punctures, right? However, puncture is easy to fix while on the road.

Presta valves on three different inner tubes failed three times in a row. Where to spot the problem? I inflate tubes to recommended pressure. Tubes were: 2x Maxxis Welter Weight 700c, 1x Panaracer Greenlite. The pump is BBB "no model name" compact cheap pump with lever. After inflation the axis of the valve seems like curved slightly, so I guess, the pump somehow damages the core of the valve. Where to look at?

When you push the pump head onto and take it off of the valve, be sure to do it in a straight line. If you insert or remove it at an angle you can bend the valve's threaded core.

A sharp edge in the hole in the rim?


I Can't judge your technique from here. maybe ream the rim out for the auto valve type stem . and use a thumb lock head, on a hose and a floor pump

so you dont move the stem as you pump, or install or remove the Pump head.

Sounds plausible. Thanks! I'll try to trace how exactly I push the pump head.

Mavic 4 CD.

Thumb lock will surely adress the issue, they just so easier to use than pumps with integrated head.

When you say the valve failed, EXACTLY what is wrong. Does the tube still hold air? Is the stem with the small nut at the tip bent? Is the valve separating from the tube? Or what else is going wrong.

Bent valve stems are a common result of poor pumping technique, or being clumsy or brutish when removing the pump. It's a user error and easily prevented with some care, but usually doesn't prevent the valve from working. If the valve is breaking near the base, it's almost exclusively because of excessive force against the valve when pumping.

So if your questions aren't yet answered, please provide more specific details and people should be able to help.

No. The tube deflates slowly. Possible to ride for ~5 km or so.

Yes, seems like so. Given what other gentlemen answered, it's 80% user error. Don't like the pump, though, it's hard to not moving back and forth while pumping. The head sits on the valve loosely, thus needs to be supported by left hand.

I've been using a push on PV pump since 1967. The secret to not damaging the valve is to make sure that the pumping force isn't put against the valve. I use two techniques for this.

One is to arrange the bike so the wheel has some room to move back and forth as the pump moves. If the wheel is braced and has no room to sway, all that force is in the valve.

The second is in the secret pump handshake, or left hand grip. Hold your hand ad if hitchhiking, with the pump held in your fingers, and your thumb braced against the rim or tire. This way the pump is braced directly to the wheel (via your hand) and you won't be pushing on the valve. This takes a tiny bit of practice, but once you get used to the grip it becomes second nature.

When finished pumping, release the thumb lock (if you have one) and instead of wiggling the pump to work it off, hold it straight and give it a karate chop near the valve to knock it clean off.

Get a good floor pump for day-to-day inflating. Use the compact pump only for emergencies.

Keep the kurl nut on the presta valve. It keeps the presta valve from being pushed into the rim and ripping the tube where the valve attaches to the tube.

i've found that i will eventually ruin a presta valve with a hand pump, so i put in just enough air to get to the next LBS and use their "complementary" pump to finish the job. but by and large the tube will be ruined in other ways first.

things are different when using my floor pump though.

Thanks for the input, everyone!

I wrap my left hand around the spokes either side of the rim. That way I am pumping into my left hand and the whole wheel, not just the valve. I make it a point to ensure the pump goes on cleanly and at right angles to the valve. (Zephal HPX pumps or Specialized floor pump.) I also make sure the pump gasket is completely past the valve tip. Then I see to it the Zephal pump stays that right angle to the wheel as I pump. I am not perfect and small bends happen, but small bends are rarely an issue.

For thirty years all my tires were pumped with Zephal frame pumps. For the first 20 those were all sewups (and got pumped frequently). I don't think I ever lost a sew-up to a broken valve. Try my hand position. And like others, I am a big fan of pumps with thumblocks and won't own a pump without (although mostly because the gaskets last so much longer).

Ben

Floor pump for home use; Topeak Turbo G for the road - it unfolds to a mini floor pump :)

OP - if you are still frustrated a couple months from now, you can drill out your rims and replace the tubes w shraders. not necessary, but some ppl do it

I can't think that I've ever ruined a Presta valve, although I do remember one that had that screw thing broken off years ago (I don't know who did it). Keep a cap on your valves when not in use.

If using a portable pump, always hold the pump head.

The Lezyne Style mini pumps have a reversible presta/schrader hose which seems like a nice idea. I gave one to my nephew so he can have something good to start with.

A 40 year old Silca Track Pump is in My house. On the road I've Managed With Silca's Impero Pumps

mending the Puncture I hang the wheel from the pump head, and as above steady the wheel and Pumphead together..


the Topeak Master Blaster Pumps are popular , they are like a Mini Floor Pump.

I had to fix a flat on the road just the other day and the pump I used was a Zefal HPX3. Attach the pump to the valve, grip the pump near the head firmly in the left fist while bracing the left fist against the rim and the rim against my thighs and pump away. Force is taken up by the fist, rim, and thighs. I have one of those little Topeak pumps on another bike and they are much easier to use and less likely to snafu the valve, but the old frame pumps, like the Zefal, do the trick too.

Personally, I have more trouble with Shrader valves than with prestas but most people seem to prefer the opposite.