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Patched tubes always have a micro leak
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For years when I flatted I didn't bother patching and just replaced the tube, wanted to try and be more frugal (even if just a little bit) and be less wasteful. Everytime I patch a tube I always get this micro leak. It holds air, can't hear or feel anything, but it deflates over long periods of time such as overnight. Then when I check it in water, there's always this teenie, tiny little bubble come out the side of the patch. Is this patching? Or do I just need more practice?

I still lapped everyone on the couch!
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Re: Patched tubes always have a micro leak [Jloewe] [ In reply to ]
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Assuming you are using vulcanized patches, there are a few things I do (get probably 70% success rate, after tossing out the ones i can't repair).

1) almost always useless to patch pinch flats. The holes created are almost always a bit too far apart for successful vulcanization to occur.

2) if it's a puncture on the seam, you have to grind down that seam before patching. If you can't grind down the seam, it's probably a lost cause.

3) cleaning area around the puncture and doing sufficient abrasion. Preferably, the area abraded is a bit larger than the area of the patch applied.

4) when applying the patch to the abraded area, apply a good amount of force. I would use pliers for this.

After not having done any patching for 5-6 years, I just got around to it a few weeks ago, as I'm running quite low on usable tubes. Patched about 20 and ended up tossing 6-7 of the ones I patched. Some of them had the micro leaks as you described, but others seem to hold air just fine.
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Re: Patched tubes always have a micro leak [Jloewe] [ In reply to ]
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A) You need more practice. I rode tires with multiple patches in the past. Use some sandpaper on the tube. Use plenty of glue on both the tube and patch, let dry a bit and then apply the patch. Should be leak free. Still happens sometimes though. Therefore i don't bother and choose option B.

B) I bring old tubes to my LBS who in turn sends it to german tire manufacturor Schwalbe who started using recycled material in their tubes back in 2015. At this moment 20% of each tube is recycled material and of every tube that is returned 100% of the material can be used.
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Re: Patched tubes always have a micro leak [Jloewe] [ In reply to ]
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If the patch is done correctly, it won't leak air. I use patched tubes for my training wheels/tires all of the time. Sometimes the patched tube seems to hold air better than a new tube. (Probably just a function of how well the tube was holding air when it was new.)

Make sure to wait a while after putting the glue onto the tube before you put the patch on top of the glue. The glue should sort of look like it's dry. If the patch seems to have peeled up around the edges and it doesn't conform to the profile of the tube afterwards (which will happen if you put a patch onto wet glue), it will leak air.

Practice and experience will help.

"Human existence is based upon two pillars: Compassion and knowledge. Compassion without knowledge is ineffective; Knowledge without compassion is inhuman." Victor Weisskopf.
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Re: Patched tubes always have a micro leak [Alvin Tostig] [ In reply to ]
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Ok food advice. I have a few failed ones I might get some more practice on.

I still lapped everyone on the couch!
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Re: Patched tubes always have a micro leak [Jloewe] [ In reply to ]
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Make sure you are using legit vulcanizing glue. Makes a big difference.
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Re: Patched tubes always have a micro leak [Jloewe] [ In reply to ]
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I've only had issues with the glueless patches, those might get you home but are not a long term fix.

The patches with the separate tube of glue are much better. Ive ridden for years on those patches.
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Re: Patched tubes always have a micro leak [Jloewe] [ In reply to ]
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Jloewe wrote:
For years when I flatted I didn't bother patching and just replaced the tube, wanted to try and be more frugal (even if just a little bit) and be less wasteful. Everytime I patch a tube I always get this micro leak. It holds air, can't hear or feel anything, but it deflates over long periods of time such as overnight. Then when I check it in water, there's always this teenie, tiny little bubble come out the side of the patch. Is this patching? Or do I just need more practice?


Thank you for concern regarding the environment. Some of my peers had always laughed at me for years when I patch tubes. For some reason they think it is because I am cheap and trying to save money. Ironic, because they mostly have no money and usually much younger and you think they would care about the environment. Anyway, two things, make sure you are using fresh glue. I find often the glue is dried up in the tube. I will repair on the side of the road, but in an effort to be more efficient, I usually just bring the tube home, find the leak, circle it with a sharpie and then wait until I have a couple of tubes before repairing.

Before applying glue make sure you are sanding the tube, especially if there is a raised seam. I like to have a big container of glue too, as I said, it tends to dry up in the tube and I have way too many patches and never enough glue.


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Last edited by: Thomas Gerlach: Jun 25, 20 12:28
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Re: Patched tubes always have a micro leak [Thomas Gerlach] [ In reply to ]
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Thomas Gerlach wrote:
Some of my peers had always laughed at me for years when I patch tubes. For some reason they think it is because I am cheap and trying to save money. Ironic, because they mostly have no money and usually much younger and you think they would care about the environment.

Embarrassed to admit that for a few years when I was brand new to the sport, I just didn't realize you could really patch tubes in general. I thought the patch kits were effectively a 'get home' solution, not a way to actually continue using the tubes. I wouldn't be surprised if a lot of people just view tubes as consumables outright, just due to not knowing.

JustinDoesTriathlon

Owner, FuelRodz Endurance.
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Re: Patched tubes always have a micro leak [Jloewe] [ In reply to ]
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One of my favorite topics, as I worked at a bike store, and have patched hundreds of tubes. I had a little old man for a boss, and he would tell us that scratching the tube, was something done out on the road, where there wasn't adequate cleaner. He taught us, that cleaning the tube with alcohol, or even windex, was superior to scratching the tube. And when cleaned well, no scratching required. So, that's that way we did it at the repair shop, and that's the way I've been doing it my whole life (unless patching a tube out on the road). I've also never had the tube seams cause a problem. The biggest step in all this, is using enough glue, and letting the glue dry all the way. Also, don't put glue on the patch. The patch is designed for a chemical reaction between the raw patch and glue, and the dried glue won't stick to the dried glue, as well as the raw patch will. When done correctly, the patch becomes a part of the tube forever.

Athlinks / Strava
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Re: Patched tubes always have a micro leak [Dean T] [ In reply to ]
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I just read the bit about cleaning from another source as well. I'm definately going to try that in the future, especially if I have to patch latex.

For the OP, I will second (or third) that you just need to practice. Even with 35 years of practice, I get lazy or in a hurry and don't do the job well resulting in a slow leak. Otherwise, all the above advice is solid and I really like the bit about recycling tubes. I'm going to have to ask my local shop, though in truth, my hope hope is to go entirely tubeless at some near future point because I really hate flat tires and love riding with low pressure and those don't mix well with tubes.
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Re: Patched tubes always have a micro leak [cdw] [ In reply to ]
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cdw wrote:
I just read the bit about cleaning from another source as well. I'm definately going to try that in the future, especially if I have to patch latex.
Cleaning the tube is a good idea, but I'm not sure why you'd be extra-careful with latex. Latex rubber reacts aggressively to the vulcanizing fluid, it's easier than patching butyl tubes.
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Re: Patched tubes always have a micro leak [lightheir] [ In reply to ]
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lightheir wrote:
Make sure you are using legit vulcanizing glue. Makes a big difference.

Really?! I’ve always just used a jar of rubber cement with pretty good success
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Re: Patched tubes always have a micro leak [mvenneta] [ In reply to ]
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mvenneta wrote:
lightheir wrote:
Make sure you are using legit vulcanizing glue. Makes a big difference.


Really?! I’ve always just used a jar of rubber cement with pretty good success

I used to feel that way. Then I patched a bunch with standard rubber cement instead of ones specifically marked 'vulcanizing'. Seemed fine! I even rode one of the patched tubes for months. But then I found out that a long time later (at least 6+months), the ones I had patched with those were developing significantly slow leaks, like the OP - half flat in 24 hrs or more.

Couldn't figure out at first what went wrong, as I felt I did everything the same, and in the past, my patched tubes that I didn't use were good in storage for well over a year (at least until I used them). Went back to glue marked 'vulcanizing' and no more of that.
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Re: Patched tubes always have a micro leak [Dean T] [ In reply to ]
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Dean T wrote:
One of my favorite topics, as I worked at a bike store, and have patched hundreds of tubes. I had a little old man for a boss, and he would tell us that scratching the tube, was something done out on the road, where there wasn't adequate cleaner. He taught us, that cleaning the tube with alcohol, or even windex, was superior to scratching the tube. And when cleaned well, no scratching required. So, that's that way we did it at the repair shop, and that's the way I've been doing it my whole life (unless patching a tube out on the road). I've also never had the tube seams cause a problem. The biggest step in all this, is using enough glue, and letting the glue dry all the way. Also, don't put glue on the patch. The patch is designed for a chemical reaction between the raw patch and glue, and the dried glue won't stick to the dried glue, as well as the raw patch will. When done correctly, the patch becomes a part of the tube forever.

Thank you, this is brilliant. I like that the Windex will also help identify exactly where the hole is by bubbling up. You have inspired me to revisit tube fixing.

when I rode in southern California in the early '80s on group rides it was common practice to just throw flatted tubular tires in the ditch along with all of the other garbage. Funny how norms have changed in a good way.
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Re: Patched tubes always have a micro leak [HTupolev] [ In reply to ]
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but I'm not sure why you'd be extra-careful with latex. Latex rubber reacts aggressively to the vulcanizing fluid, it's easier than patching butyl tubes.

Probably because latex doesn't "rough up" very efficiently so if I don't have to use the sandpaper, that is a plus. Also, latex tubes nearly always fail at the seam by the valve for me so I am always trying to patch awkward locations.
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Re: Patched tubes always have a micro leak [Jloewe] [ In reply to ]
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Jloewe wrote:
Ok food advice. I have a few failed ones I might get some more practice on.

I came here for the food advice. What do you recommend - pizza? I would like to practice on different toppings.

https://www.strava.com/...tes/zachary_mckinney
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Re: Patched tubes always have a micro leak [plant_based] [ In reply to ]
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plant_based wrote:
Jloewe wrote:
Ok food advice. I have a few failed ones I might get some more practice on.


I came here for the food advice. What do you recommend - pizza? I would like to practice on different toppings.

If you get a hole in the crust while you're rolling the dough, don't worry -- you can patch it, you don't have to throw it away and start over! And, in most circumstances, the patched dough becomes indistinguishable from the original (just don't coat the crust with too much oil, which impedes bonding of the patch to the hole).

This thread is useful, I'm learning a lot. I haven't ever patched any tires but have been saving the flatted tubes.
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Re: Patched tubes always have a micro leak [plant_based] [ In reply to ]
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plant_based wrote:
Jloewe wrote:
Ok food advice. I have a few failed ones I might get some more practice on.

I came here for the food advice. What do you recommend - pizza? I would like to practice on different toppings.

Ha! Auto correct and goofing off at work.

Well to answer your question, I’m a big fan of anything with bacon. Try jalapeño and bacon. Or banana peppers and bacon if you like it a little more mild.

I still lapped everyone on the couch!
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