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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

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Old 11-25-09, 02:06 AM   #1
mrvile
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I keep getting the same kind of flat... (weird)

Okay so tonight I flatted both front and rear to the same type of flat. Here's a picture of what is happening:



The red circles are where the punctures keep happening. Sometimes it's one side, sometimes it's both, but both points seem to get weak at the same rate. I'm pretty sure it doesn't have anything to do with my rim...it's well taped, no burrs, and when I install the tube/tire I'm always VERY careful around that area. Surprisingly enough, it generally flats at very random times. Tonight I was just sitting in my room when I heard my tire lose air (usually I'm not on the bike when it happens). Does this happen to anyone else? Can anyone explain what's happening and how I can prevent it?

For the record I'm running Eighthinch Tessa wheels, similar to DP18 and Deep-V's, with various tires and tubes. This has happened when I've had Michelin 23's and with my current Ribmo 32's. I use QTube brand tubes because that's what my LBS sells.
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Old 11-25-09, 02:24 AM   #2
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It's caused by bending the valve while attaching and removing the pump.
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Old 11-25-09, 02:59 AM   #3
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Originally Posted by Charlie_Zulu View Post
It's caused by bending the valve while attaching and removing the pump.
EPIC DOH!

Of all things to suck at, why do I suck at pumping my tires

I'll add that to the list of things to be careful with on my bike...
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Old 11-25-09, 03:15 AM   #4
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Faluty tubes maybe??? I have in 30 years never seen this. What tubes are they????
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Old 11-25-09, 03:24 AM   #5
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Originally Posted by Charlie_Zulu View Post
It's caused by bending the valve while attaching and removing the pump.

Please explain...while the tube is on the rim the valve is in a fixed spot no???? And if this does happen it must be a weak tube??? How do things like this happen???
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Old 11-25-09, 03:29 AM   #6
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We sell Q Tubes at my shop. They are Quality Bicycle Products house brand. I have never seen this before. I would guess maybe your LBS has some old tubes on their shelf. I would go ask them about how long they have had their tubes? We go through about 50-75 tubes a month in almost all sizes so ours stay pretty fresh. Well, as fresh as they are from QBP.
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Old 11-25-09, 03:37 AM   #7
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Well, as fresh as they are from QBP.

Who knows how long they sit in the warehouse...or trailer waiting shipment?
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Old 11-25-09, 06:55 AM   #8
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Check your rim tape. Even a tiny rough spot will pop a tube. You put a lot of stress on a tube when riding and the rubbing back and forth on the rim tape burr will pop the tube. Even if you can't feel it, I'd go ahead and change the tape.

Or try buffing the tape with emory cloth.
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Old 11-25-09, 06:56 AM   #9
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Are you using a hand pump without a hose. I can't keep those straight enough and always end up pulling the valve off.
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Old 11-25-09, 09:24 AM   #10
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Check your rim tape. Even a tiny rough spot will pop a tube. You put a lot of stress on a tube when riding and the rubbing back and forth on the rim tape burr will pop the tube. Even if you can't feel it, I'd go ahead and change the tape.

Or try buffing the tape with emory cloth.
+1. If the rim appears to be OK, the first thing to do is replace your rim tape.
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Old 11-25-09, 10:10 AM   #11
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The particular location of the flats is suspicious. It is at the joint between the valve base and the tube, which often indicates faulty manufacture of the tube or aging damage. I've had a lot of failures of the valve base joint on Bontrager tubes, and don't use them anymore. I'd try a different brand.
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Old 11-25-09, 10:28 AM   #12
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Who knows how long they sit in the warehouse...or trailer waiting shipment?
Exactly my point. These things could have been in the warehouse for years before your LBS got them.
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Old 11-25-09, 10:30 AM   #13
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The particular location of the flats is suspicious. It is at the joint between the valve base and the tube, which often indicates faulty manufacture of the tube or aging damage. I've had a lot of failures of the valve base joint on Bontrager tubes, and don't use them anymore. I'd try a different brand.
how tight are you putting the nut on your valve?
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Old 11-25-09, 10:35 AM   #14
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Originally Posted by Charlie_Zulu View Post
It's caused by bending the valve while attaching and removing the pump.
tubes with the threaded valve stem are a lot harder to disconnect from the pump and might cause me to wiggle it a little. No such problem with the smooth ones.
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Old 11-25-09, 02:47 PM   #15
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how tight are you putting the nut on your valve?
Good question for the OP; first thing I thought of. That nut isn't a fastener, don't use it like one.
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Old 11-25-09, 10:59 PM   #16
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I had this kind of flat a couple times. It was user error, I think. While seating the tire, I was pushing the valve stem up into the tire to help the beads seat near the stem. Then when I pumped the tire up, a little nipple-dimple-bubble of the tube would inflate under the hard rubber disc around the stem (between the tube's rubber reinformcement disc, and the rim). I figured out what it was because the hole was on the end of these little nipplish things that hadn't been there before I installed the tube.

Doh!

I changed my habits, and it never happened again.

That's what happened to me, anyway.
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Old 11-25-09, 11:56 PM   #17
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When you're stuffing tubes into tire do you go down one side and work it all the way around, or do you do both sides away from the stem and meet them at the bottom? I feel like doing the 1st method could introduce a bit of pull near the stem in some situations, so I do the 2nd method, like so.
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Old 11-26-09, 02:02 AM   #18
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+1. If the rim appears to be OK, the first thing to do is replace your rim tape.
Already did that...didn't seem to help.
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Old 11-26-09, 02:12 AM   #19
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how tight are you putting the nut on your valve?
I actually stopped using the nut on the valve, because I've used the smooth valve ones that hairnet is talking about which worked fine...initially I assumed the nut had something to do with the punctures and stopped using them altogether. At this point I'm still not exactly sure what they are for other than preventing the tube from pushing down slightly when I attach the pump hose, which doesn't seem to be adding that much stress.

Is this what is resulting in epic fail?
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Old 11-26-09, 02:13 AM   #20
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tubes with the threaded valve stem are a lot harder to disconnect from the pump and might cause me to wiggle it a little. No such problem with the smooth ones.
That might be the case...the tubes I use now are all threaded, and the few smooth valves I've used in the past never had this problem.
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Old 11-26-09, 02:18 AM   #21
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I had this kind of flat a couple times. It was user error, I think. While seating the tire, I was pushing the valve stem up into the tire to help the beads seat near the stem. Then when I pumped the tire up, a little nipple-dimple-bubble of the tube would inflate under the hard rubber disc around the stem (between the tube's rubber reinformcement disc, and the rim). I figured out what it was because the hole was on the end of these little nipplish things that hadn't been there before I installed the tube.

Doh!

I changed my habits, and it never happened again.

That's what happened to me, anyway.
I'm trying to understand what you're saying and I think I almost have the same problem. When I check the tube after it flats, I notice that if there isn't a punture on both sides, the side without the puncture has obviously weakened to the point where it forms a nipple-dimple-bubble thing (trying to make the connection here). Also, when I install my tire, yes, I do push up on the valve gently to get the tube to stay in the tire while I'm seating the beads. I make sure I do this carefully, and I can't really think of any other way to approach it.

Can you explain how exactly you've changed your habits? Thanks.
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Old 11-26-09, 02:25 AM   #22
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When you're stuffing tubes into tire do you go down one side and work it all the way around, or do you do both sides away from the stem and meet them at the bottom? I feel like doing the 1st method could introduce a bit of pull near the stem in some situations, so I do the 2nd method, like so.
When I'm stuffing the tubes into the tire, I start with the valve then make my way evenly around both sides, as the video shows. However when I'm seating the tire bead around the rim, I generally start with the side opposing the valve, go one way towards the valve, seat the bead by the valve using the apparently faulty technique that mcgreivey mentioned, then come back down towards the opposing side so when I really need to use force, I'm far away from the valve.
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Old 11-26-09, 02:27 AM   #23
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your inner wheel band hole is stretching out and showing some edge of the hole and letting a pinch spot happen, this use to happen to one of my rims before I used some electrical tape over the hole, then poked a small hole so it goes in the stem hole to protect the edge
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Old 11-26-09, 02:31 AM   #24
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However when I'm seating the tire bead around the rim, I generally start with the side opposing the valve, go one way towards the valve, seat the bead by the valve using the apparently faulty technique that mcgreivey mentioned, then come back down towards the opposing side so when I really need to use force, I'm far away from the valve.
That could be the problem. It isn't where you're applying the force that's the problem, it's that you're working it all the way around and across the stem area, potentially pulling it there. Seat the tire the same way you seat the tube and see if your flats still happen. (like the vid)
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Old 11-26-09, 02:31 AM   #25
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your inner wheel band hole is stretching out and showing some edge of the hole and letting a pinch spot happen, this use to happen to one of my rims before I used some electrical tape over the hole, then poked a small hole so it goes in the stem hole to protect the edge
I've already tried that...also the puncture spots are pretty far away from the actual valve hole, about 1cm or so...but maybe I'm just not understanding what happens to the tube in the rim when I fully inflate it.
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