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Old 06-10-09, 04:45 AM   #1
NOS88
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Presta Valve Head Snapped Off

It must be because I read Denver's thread about two flats on one ride. Yesterday I got a flat. The old tube was in pretty bad shape. I pulled out the spare tube I carry and while unscrewing the top/head, it snapped off. (See photo with line for the part I'm talking about). I didn't pull it off/out. I could see where the metal actually sheared. Has anyone else had this happen? It was a brand new tube (purchased this spring). So, out comes the patch kit and wouldn't you know it the glue tube is dry. Lucky for me I had a single Park patch lying in the bottom of the bag.
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Old 06-10-09, 04:50 AM   #2
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Yes I have had a valve break off as well. I bought a new tube.
Lucky mine happened at home when checking pressure before a ride.
To be honest I am amazed it does not happen more often, seems to me those valves are pretty fragile.
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Old 06-10-09, 04:54 AM   #3
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Yes, I had it happen once, but I attributed it to fatigue from repeated use as I inflate my tires before every ride. Hasn't happened since. Maybe you just get a bad one once in a while.

Last edited by crazyb; 06-10-09 at 05:09 AM.
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Old 06-10-09, 05:08 AM   #4
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I buy my tubes a dozen at a time. I just got a delivery from PricePoint yesterday. I snap off more valve heads than flats by a 3/1 ratio. I think it's the quality of the materials that have made the valves fragile. At $1.70 each it's more of an aggravation, I wonder if I paid full price for good tubes if I would have better results. I was looking at the valves on a couple of my vintage "sew-ups" and the thickness of the brass is substantial when comparing it to today's tube valves. My two grown son's also seem to always need a tube before rides, and end up with one of mine, they take my beers too.
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Old 06-10-09, 06:12 AM   #5
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I broke one off a couple days ago also. There must be a rash of this going on right now. Could be sun spots.

The tube seems to be holding air normally and I can add air as needed. I guess the drawback is that if I needed to let the air out of the tube it would be a bit of a problem to press the valve down.
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Old 06-10-09, 06:17 AM   #6
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Originally Posted by NOS88 View Post
It must be because I read Denver's thread about two flats on one ride. Yesterday I got a flat. .
Somehow, I always get the blame.

Sigh.

Yes, I have had the Presta valve top break off - but, luckily, at home. This has happened when I was attaching the hose connection and wasn't taking care.
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Old 06-10-09, 06:23 AM   #7
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Have yet to have it happen, but reading this, it probably will happen soon. Off to buy some spare tubes.
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Old 06-10-09, 12:44 PM   #8
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I have never broken a valve head off any tube- but I have had the base of the valve get a split in the rubber surrounding it.

This may be down to the quality of tube I buy as I always go for the better quality Michelin- Continental or Schwalbe tubes.
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Old 06-10-09, 02:40 PM   #9
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Originally Posted by stapfam View Post
I have never broken a valve head off any tube- but I have had the base of the valve get a split in the rubber surrounding it.

This may be down to the quality of tube I buy as I always go for the better quality Michelin- Continental or Schwalbe tubes.
My most common innertube problem is cracking at the base of the valve stem. I swapped bikes at work yesterday and rode the Peugeot (27x1-1/4" wheels, old school non-hooked rims) home, so that I could replace the ripping Brooks saddle and do some other maintenance on it. I rode 7 miles home on about 60 PSI from my frame pump, then topped it to 80 PSI using my floor pump when I got home. Two hours later, we heard a big bang and a hissing sound, almost like a soda can exploding. I went out to the front doorstep and found that my Schraeder valve body was ripping away from the rest of the tube, creating the abrupt blowout pressure loss. I fondly remember the good old days when Presta and Schraeder valve bodies came with wide metal bases which kept them from failing in this manner. Somewhere along the line, tube manufacturers got cheap, and now we are all paying for it in terms of reliability.
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Old 06-10-09, 04:07 PM   #10
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I haven't broken a Presta valve since I quit using my old Blackburn Framefit pump. I've got a Serfas pump in the garage and a Road Morph on the bikes both of which have locking heads attached to a rubber hose. My theory (and it's worth every penny it'll cost you!) is that the torque exerted by using the straight pump stresses the valve stem. Some Continental tubes, BTW, actually have removable/replaceable Presta stems.
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Old 06-10-09, 04:33 PM   #11
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I broke one off last week. Changed tubes and decided to try out my never used Pedros ego pro inflator. Of course it didn't work. Glad I was home getting ready for a ride and not in the middle of one!
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Old 06-10-09, 04:50 PM   #12
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I would break them and bend them until I bought my Topeak JoeBlow ace - a fantastic pump. It goes on and off cleanly and does not damage the valve.
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Old 06-10-09, 07:04 PM   #13
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I have never broken one and I air my tires up a lot. I have a joe blow for the garage and a road morph on both bikes. I haven't even had a flat in a very long time but of course now I will probably have a flat tomorrow on the way to work and break the stem off of the new tube after it is back on the bike.
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Old 06-10-09, 07:27 PM   #14
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I had a bent one once, must have happened removing the inflater. I made the mistake of trying to straighten it, and it snapped off. I have a bent one on another bike right now, but I'll live with it, now I know how brittle they are.
Remind me again why Presta valves are better than Schrader?
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Old 06-10-09, 10:48 PM   #15
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I twisted it off once, but have broken two when I pulled the pump off. If there is enough air in the tire, you're still good to ride. I have done a 50 and an 80 mile ride after breaking it.
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Old 06-11-09, 04:42 AM   #16
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Quote:
Originally Posted by John E View Post
My most common innertube problem is cracking at the base of the valve stem. I swapped bikes at work yesterday and rode the Peugeot (27x1-1/4" wheels, old school non-hooked rims) home, so that I could replace the ripping Brooks saddle and do some other maintenance on it. I rode 7 miles home on about 60 PSI from my frame pump, then topped it to 80 PSI using my floor pump when I got home. Two hours later, we heard a big bang and a hissing sound, almost like a soda can exploding. I went out to the front doorstep and found that my Schraeder valve body was ripping away from the rest of the tube, creating the abrupt blowout pressure loss. I fondly remember the good old days when Presta and Schraeder valve bodies came with wide metal bases which kept them from failing in this manner. Somewhere along the line, tube manufacturers got cheap, and now we are all paying for it in terms of reliability.
Might try cutting a piece from the blown tube, cutting a hole and slipping it over the stem before mounting the tire-might help. ALso, if using a stem with a nut on it, don't tighten the nut down against the rim when riding-that way, if the tire "slips" a little under hard braking/whatever, the stem can "give" a little, instead of pulling away from the tube.
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Old 06-11-09, 05:05 AM   #17
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How far are you folks unscrewing the stem nut. It only needs a half turn to 1 turn to unlock the valve. If it is unscrewed too far, the pump head will have a tendency to snag. If the pump is pushed too far onto the stem, it may hit the valve head and also bend it.

Think of the presta valve as a flat plate with a rubber seal at the bottom of the stem tube. It opens when air pressure is higher on the outside than on the inside. It closes when pressure is higher on the inside than the outside. The threaded rod and nut are only there to prevent vibration from causing the valve to "bounce" and burp out small amounts of air.

There is no reason to unscrew the nut too far or to press the pump head on any more that the minimum that will allow an air seal when the pump lever is tightened.
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Old 06-11-09, 05:47 AM   #18
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I am not going to say anything about valve stems. I fear the Flat Fairy.
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Old 06-11-09, 06:16 AM   #19
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[QUOTE=maddmaxx;9081569]How far are you folks unscrewing the stem nut. It only needs a half turn to 1 turn to unlock the valve. If it is unscrewed too far, the pump head will have a tendency to snag. If the pump is pushed too far onto the stem, it may hit the valve head and also bend it.



Thanks, I have been opening the valve all the way, and though I haven't broken one, I have been concerned about the apparent fragility of the stem.
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Old 06-11-09, 06:19 AM   #20
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I am not going to say anything about valve stems. I fear the Flat Fairy.
I laugh at the flat fairy...................
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Old 06-11-09, 06:25 AM   #21
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You can do several things to keep this from happening. First always inflate with the value at the exact bottom ot top of the wheel si the chuck slides directly on and off. Open the value and push the stem in to let a little air out and make sure the value isn't pushed off to the side. Also use the stems without threads. There's no reason to use those nuts anyway.
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Old 06-11-09, 07:31 AM   #22
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(1) Cheapskates get the tubes and presta valves they pay for. Even good quality tubes from known brand name tires manufacturers aren't that expensive. Quality assurance procedures do cost money.

(2) Presta valves are more practical for road bikes with high pressure tires, but, they are more delicate and you have to take some care about how roughly you handle them.
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Old 06-11-09, 09:14 PM   #23
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Avoid the problem altogether with schraders. bk
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Old 06-11-09, 09:52 PM   #24
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Put a little lubricant , Vasaline, I use lithium grease,etc, on a swab and wipe it lightly inside the pump to lube the "O" ring or whatever they use for a seal. Add a very small amount to the presta stem and the pump head goes on an off slick as a goose ( this lesson and recomendation from my lbs after I had snapped a Presta) OLE it works and fixed a pump I was ready to throw away because I was having to push and pull the head on the valve. It is now better than new.
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Old 06-12-09, 07:07 AM   #25
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Avoid the problem altogether with schraders.
Yeah right. Ride a hybrid or mountain bike too.
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