Rim value hole eating tubes??

[Climb01742]

I bought a pair of lightly used H Plus Son wheels and I've had 3 straight flats on the rear wheel. I've checked everything I can. There are no objects stuck in the tire. My fingers can't find abrasions or rough edges inside the tire, rim or rim tape. But what I have found on the last two tubes is this: where the value enters the tube, it has separated right at the base of the value stem. It may have happened on the first tube but I didn't check. But two tubes in a row that flatted and separated in the same spot after only a few hundred yards of riding seems more than a coincidence. Is there any way the value hole in the rim could be cutting, twisting or angling the value stem so it pulls away from the tube? Any suggestions for what I should check or try? I want these wheels to work but constant flats ain't helping or fun. Thanks in advance for ideas and suggestions.

[Ken Robb]

If the hole in the rim is a bit oversize it's edge might make contact with the thin part of the tube rather than the reinforced part that supports the valve stem.

I would look for a tube with a larger reinforced area, see if I could fit a washer over the valve stem or slip the stem through a piece of duct tape to provided more support around the stem/tube interface.

I had a similar problem once when I reduced tire pressure quite a bit while keeping the stem lock nut screwed down tight. The nut worked fine at higher psi but at lower pressures the tube seemed to moved around enough to pull the stem out of the tube.

[biker72]

Wow 20 views and no responses.
Here is what I would do:
Pull the rim tape off enough to access the valve hole. Check for burrs or sharpness around the hole. Try some light sandpaper on the inside of the rim around the hole to smooth things out.

I've had some mechanics tell me to put a piece of electrical tape around the valve hole under the rim tape.

You're not over inflating the tire??

[makoti]

I had this happen once. Ran through about four tubes. All cut the same place, base of the stem. Funny thing was, it turned out to be really crappy tubes. Bad batch, I guess, since I bought them all at the same time. After I got a different brand, no more troubles.

[bobswire]

Originally Posted by makoti

I had this happen once. Ran through about four tubes. All cut the same place, base of the stem. Funny thing was, it turned out to be really crappy tubes. Bad batch, I guess, since I bought them all at the same time. After I got a different brand, no more troubles.

Same, bad run of tubes,separation at base of stem.

[MattTuck]

Is it possible this is a run of defective tubes?

If you've ruled that out, I would pursue the above advice. Trying to make the valve hole area smoother and more reinforced (whether that be filing burs in the drilled hole, duct tape, electrical, etc.) is probably the way to go.

[Climb01742]

Ah, I hadn't thought about defective tubes. I'll check to see if they were all the same manufacturer, which could be likely since they were all my longer value size to clear the deeper rim.

Inflated to 90 psi so not over inflating.

I'll try to lift rim tape. Applying electrical tape sounds promising.

Thanks everyone. Flats drive me batty.

[John H.]

I had an issue exactly like this about a month ago.
I finished a ride and the next day my rear tire was low- I aired it up and forgot about it (then I took the next four days off and really forgot about it).
Next ride I aired it up- noticing that it was low but thinking it was because I had not ridden in several days.
45 min out I am almost bottoming out- stop to check, low but not flat. I pump a bunch of air in it and continue.
I get another 15 minutes before I am low again- climbing- I can feel it bottoming out.
I change the tube- while changing I check closely for something in tire- seems clean.
I ride another 30 minutes or so- almost flat again. Now I am halfway through my ride and 90 minutes (with a good tire) from home.
I try to pump up again because it delayed it before- My pump fails. Specialized mini pump- it is now sucking air rather than pumping.
I see a lady in the same parking lot with a bike in the back of her SUV- I ask if she has a pump. She doesn't but she has a quickfill- saved for the moment.
I ride another 30 minutes and arrive in Pt Reyes Station. I am hopeful that Pt Reyes bike shop is open but I was remembering that the shop is closed on Monday. Sadly, I am correct- it is closed on Monday.
I start to ride south to get home- It is about 1 hr home with no mishaps. Tire is pretty low.
At town of Olema I see to guys on touring bikes- they are Scots visiting US and bike touring around the area.
I ask to borrow a pump from them. They both have pretty crappy mini pumps and I think my net air gain is zero (I hope they don't flat).
I make it over the hill and about 30 minutes from home I am bottoming out again. Have a tube- but no pump.
I stop- a guy rides by and asks me if I need help. I ask if he has a pump- no pump, but has a quikfil. I quickly install the tube. I check tire again and can feel nothing- looks and feels perfect. Hit it with the quikfil, realize that I pinched the tube.
I tell the guy to go because he mentioned that he was on a ride of about 125 miles and had a good ways to go.
Ride last 10 miles home with a flat.
Miraculously the wheel is perfect (thanks Ergott).
After this I replaced both rimstrip and tire- because days like this are B.S.
Moral of the story. Replace both- don't have it turn into a problem on another ride.

[93legendti]

Originally Posted by MattTuck

Is it possible this is a run of defective tubes?

If you've ruled that out, I would pursue the above advice. Trying to make the valve hole area smoother and more reinforced (whether that be filing burs in the drilled hole, duct tape, electrical, etc.) is probably the way to go.

I've done this...works well...

[Birddog]

Most times when I've seen this it was bad tubes as others have pointed out. I think when they get old this is common.

[jc031699]

Originally Posted by MattTuck

Is it possible this is a run of defective tubes?

If you've ruled that out, I would pursue the above advice. Trying to make the valve hole area smoother and more reinforced (whether that be filing burs in the drilled hole, duct tape, electrical, etc.) is probably the way to go.

I've done this also- smoothed out the edge of the valve hole from the tube side of the rim using a fine bur on a Dremel, until it was smooth to the touch. Did not increase the diameter noticeably, worked well. Similar to what is described when folks prep a tubular rim when it is built, to eliminate a bump at the valve.

[marciero]

Another idea-When installing the rim tape, I make the valve hole with a pencil or something sharp and widen it out gradually by turning and pushing the pencil through (at least I think I used a pencil last time) This has the effect of wrapping the rim tape around the valve stem hole. It certainly makes sense to smooth or de-burr beforehand as others have suggested.

[Special K]

I would reiterate the advice regarding an extra piece of tape on the rim. What I do is take a small piece of Velox tape, about an inch or so long, cut a small hole and the use a closed presta stem to push through so the size is right. I've started doing this on all my wheels. I like the 1 piece rim stripes like FSA or ENVE and put the Velox underneath.

Hope this helps.

[Climb01742]

Wow, lots of great ideas and suggestions. I'm working my way through them with my rim. I truly appreciate everyone taking the time to post. One more example of why this is a special place. Thank you for your help one and all.

[josephr]

go tubeless?