Although I always carry a spare tube I also carry patch kits. Park tool ,1 glue-less, and 1 glue kit. They have been kept in my messenger bag and seen temps ranging from 90+ down to below freezing for the last year and a half. The kits are a rather cheap insurance policy for flats. But how long before its time to replace them? I'm guessing after a while the adhesive loses it effectiveness. What's a good rule of thumb?

If the "glue" comes in a metal tube, then it's a few years unused, or a few months (up to a year, if you're lucky) once you break the seal.

Thanks....

You can help the glue to last longer after the tube is opened by squeezing out all of the air before you put the cap back on.

You can buy glue separately from patches, too. I try to always carry an unopened tube as well as an opened one. Try the open one first; if it's a dud, open the new one and remember to replace it when you get home.

I buy both glue and patches on eBay. Patches in sheets of 50 or so, usually from China. I use a lot of patches, and the Chinese ones are fine.

I agree it's a good idea to carry glue less patches as well, but I only use them as a last resort. They doubt last long and are hard to replace when they go bad.

I've experienced quite a bit of variability in how long the sealed tubes last. Some many years and others much less. The tubes are solid uninterrupted aluminum except for the flat end where they're filled and then folded to seal. I imagine the variability arises in the quality of the seal in the folded end.

I've found unopened tubes dried out occasionally. I buy additional tubes of cement as needed. For home use I buy an 8 oz can from the auto parts store.

I use Park glueless patches, and have had them last more than 2 years.

I usually have them fail when pressurizing the tube looking for the next pinhole puncture.

Glueless patches stored in my bag become useless after a a few months or a year at most. Our high humidity and heavy rain kills them. On a tube they start to fail after a year. I'll carry them for convenience but you can't depend on them.

Tubes of glue once opened dry up fast enough that you might as well use them up once opened and only carry unopened tubes on the bike. Sure it's OK for awhile but I'll forget about it if I go a few months without a flat, then when you need it it's dry.

I'm still using patches (the kind that require vulcanizing solvent) from a kit that's 20 years old. As long as they still have the foil on one side and cellophane on the other sealing out air, they may last a lifetime and beyond. It's the tubes of solvent that don't last long enough.

Life expectancy of my patch kits? Months. Then it's no more patches and an empty tube of glue. Life expectancy of my tubes? 5 patches is norm.

Ben

I still use Rema patches that I purchased in the late 1970's and have no concerns about their performance. As long as your glue is compatible and not dried out, there should be no issue.

This helps a lot.

I bought a can of Slime glue and poured some into an old nail polish bottle my wife gave me. (I cleaned the bottle w/acetone, BTW.) She has polishes that have lasted years w/o drying out, and it works the same for the glue. The applicator brush is just right for patching. When closed for a while (e.g. months between punctures) the cap gets stuck on, but the design of the cap solves this, too. (It's tall & easy to grip) Apparently, nail polish does the same thing. I often wondered why those caps were so tall..

On rides, I use peel&stick patches as a temporary repair until I get back home. I keep 'em in an old 35mm film can in my kit.