7 exact flats in 7 tubes in 2 weeks.......help

Can anyone figure out this problem Im having with tube blowouts. 7 tubes in 2 weeks , exact same blow out in the same place. See the 2 pimple type blowouts ½” on either side of the valve stem……I rode all last summer and through the winter on this exact rim and tube and tire with no problems. This spring this problem showed up. I’ve been to 4 local bike shops and nobody has an answer, they love selling me tubes though. It seems to me as if the tube is stretching and this is the weak point in the tube. But I haven’t got the answer yet….help Its spring and I want to ride……. 6-1" 275lbs......last summer I was 255lbs (a comfortable winter) I ride the same course, 12.25 miles 5 days a week.....thanks in advance....Greggo

Tire: Schwalbe 47-622 28x1.75

Rim: Weinmann 700 x 18c / 23c new rim tape

All tubes were : Specialized 700 x 32-50

 

What does the rim strip around your valve hole look like? It may be pulled away or have sharp edges. The other side to the valve looks like it may be bulged too?

I'd deburr the valve hole with a drill or file and use a few layers of cloth tape with a hole punched in it to reinforce the rim strip around the valve hole.

 

thanks for the reply, the prob;em was a defective batch of tubes. I purchased a different brand tube, installed it and have ridden 30 miles on it with no loss of pressure. I removed the new tube and can see no evidence of failure at all in the tube.
Greggo

 

I hope the LBS refunded your money on those defective tubes.

 

It has gotten to the point where I inspect my tubes upon purchase. I have bought tubes from a shop before, walked out to the car and opened the box to inspect them, finding that 2 out of 3 had large punctures in them as if done intentionally.

Walked right back in to exchange them. Owner thought I was crazy and that maybe I might have done it. He opened a few more boxes finding 2 more. Hmm, maybe some clown poked them for fun hoping to strand some cyclist out on the road somewhere.

 

Purposely poking holes in tubes...wow. Maybe that's why my LBS keeps their tubes behind the counter?

I had one tube I bought that came with a spit seam, my LBS exchanged it no questions asked.