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Questions on tubes: patching and sizing:(6 posts)

Questions on tubes: patching and sizing:LAIrish
Sep 30, 2001 2:11 PM
So, picked up my bike from the LBS after getting some new components and tuning, took it out of the car that evening, went to check it out and: Oops, flat tire. Patch tire, pump up, around sixty lbs, phzzzzzz. Another puncture. Check out the rim and find a hole in the rim tape exactly where the two punctures were (put the tube in in reverse from when took it out). Check out extra tube. Notice it's 700 x 28 and I have 700 x25 tires. Go to other LBS (the original is one man shop and is closed while he attends the retailers convention in Vegas), buy new rim tape and 2 700 x 25 tubes. Get back, and notice that original tube (installed by original LBS) was also 700 x 28. Put on new rim tape, patch old tube, reassemble. All seems OK.

Two questions: (1) Is a patched tube OK for riding, or just for getting home to where you can replace it? (1.a) If OK for riding, after how many patches does one replace it? (2) Is it important to have the tube size match the tire size? (2.a) If so, how important and what is the potential of having x28 tubes in my x25 tires.

re: Questions on tubes: patching and sizing:Wagnerite
Sep 30, 2001 4:19 PM
28mm tube in a 25mm tire is probably ok.

it's perfectly fine to ride on a patched tube. some people only use un-patched tubes, but at my income, i ride tubes with up to 6 or 7 patches on them. recently had a bike shop build up a bike and gave them tubes with 5 or 6 patches, they kinda laughed at me b/c i was building up a pretty expensive bike, but what the heck, i'm saving 5 bucks everytime i patch a tube. i have like 8 tubes that i rotate each of them with anywhere between 5 to 9 patches on them. Look at it this way, never will you get another puncture where you put the patch.
Tube's fine, you're fine, all god's children are finecory
Oct 1, 2001 7:46 AM
No reason not to ride a patched tube forever. I can count the number of patch failures I've had on my thumbs. There is no absolute limit to how often you can patch--I live in Big Thorn Country and I often have half a dozen patches on a tube. I usually don't trash them until they tear at the valve (unpatchable) or I get a hole so close to another one that the patches would overlap. Throwing away one $5 tube is no big deal, but throwing away 20 of 'em runs into money.
Don't sweat the size. I have bikes with tires from 23 to 35mm, and I use tubes without regard to size except that the very biggest ones (which I don't buy anymore) won't fit into the very skinniest tires. I just buy fairly skinny ones (20-23? I get 'em half a dozen at a time and I don't remember) and use them in everything.
re: patches are your friendsdzrider
Oct 1, 2001 8:32 AM
I've had a few patches, out of many that I've used, develop slow leaks. Since then, I keep a new tube in the seat bag and ride patched tubes, so I find slow leaks in the basement not on long rides.
Tube size matchKerry Irons
Oct 1, 2001 5:33 PM
Generally, tubes are OK as long as 1) they aren't so much smaller than the tire that they're stretched like a baloon when pumped or 2) so oversized that they're wrinkled when you put them in. The first case is highly unlikely unless you have super narrow tubes (18s) in very large tires (32s). After all, you typically stretch the tube quite a bit when you pump it up to find the hole to patch it. Undersized tubes will tend to lose air a little faster. A wrinkled tube is a flat waiting to happen, as the wrinkle will rub with every revolution of the wheel as the casing flexes. I never even count the number of patches on a tube, and only throw them out as noted by another poster: tear at the valve stem, overlapping patches, large hole or tear, etc. I think I've had two patch failures in the past 30K+ miles of riding, and those were probably my fault.
patch failuresjw25
Oct 4, 2001 7:43 AM
The sizing issue has been covered pretty well, but I'll add this : given the difference between the real size of a "23c" tire from different manufacturers (as an example; it also carries on to the bigger sizes), a 3mm difference in tube sizing is no matter. I have "23c" tires that measure 22mm wide, 23mm, and 24mm, all on the same rim, at the same pressure.
Also, I've yet to see a tube package that doesn't give a range of sizes; the Michelins I use are 18 - 25mm, I think, and they're pretty thin and light, so a "standard" tube of decent quality should have a greater spread.
As for patch failures, I've had a few in 5 years of riding, but the early ones were almost certainly my fault (more cement is not better - when the instructions say "an even, thin layer", it's what they mean.
Since learning that, I had one Park glueless patch de-stick itself, but the 2nd gen. of those have worked flawlessly so far. In fact, one mountain tube still has one of those mounted, because I couldn't get the thing off to replace with a regular patch. It's seen 2 years of steady use like that. I've had one auto tube patch fail, but the rubber they used is softer, and seems to have pulled apart under pressure.
Now get out there and ride.