I've been attending a night course in very basic bice mechanics -- which was a blast.

The next step was to turn here to figure out what the rudimentary stuff to buy and bring would be, and while doing this I noticed something funny: why is everybody recommending both a patch kit and a spare tube? I mean, if you switch to a new tube you won't be fixing the old one, correct?

Just wondering, that's all.

You have never had more than one flat on a ride?

I fix the old tube when I get home, and put it back in my bag. I've got tubes with 3-4 patches on them. They hold air just fine.

I carry just a spare tube during my commutes and patch the flat tube when I get home.

If my commute is going that bad, I just toss the bike on the bus. That has only ever happened once in my years of commuting.

Multiple calamities of course. I'm of the "try to patch it first on the road" persuasion. And sometimes a patch won't take or you have gotten multiple holes in the same tire at one time and run out of patches. Then you need the spare. And I have gotten flats in both tires at the same time before.

Though in practice I rarely carry a spare tube, just the patch kit. I'll carry both if I'm on a long ride out in the country. Usually the spare tubes stay at home.

1. I can pop a bead, pull out part of the tube, patch it, and push it back in, a lot quicker than taking off the entire wheel to replace a tube.

2. Multiple flats on a ride.

Nope. Never. But I guess it's just a matter of time now...

Redundancy.

I've changed to a new tube, only to find it also had a hole. Also installed a new tube thinking I found and removed the piece of glass that punctured the tube, only to find another piece of glass in the tire that punctured the replacement tube. Glass fields are common around here.

Patches won't fix a large gash in the tube or break near the valve stem. Recently had a slow leak that couldn't be found in order to patch, so it had to wait until home. Also carry boot material (small piece of tyvek) for tire sidewall cuts.

Ride long enough and you'll eventually encounter all of these issues.

I always carry a spare tube and a patch kit......have never used the patch kit while on the road for my own tubes. I have however, used the patch kit many, many times when I have stopped for another cyclist with a flat and no spare tube.....

I 'm riding to the train station, so time is limited. I leave the house in time to fix one flat if need be.

If I flat, I change out the tube still catch the train, then patch the bad tube later.
If I flat again, I must accept that I'll miss my train, but I can still patch the best tube and ride on to catch the next train.

I've never had a single flat with my current tires while out on the road. That said, it seems possible that a piece of debris that causes one flat could go undetected and puncture my spare tube as well.

in case the valve craps out on the tube you're repairing

I am wondering about getting a CO2 thingy for my road bike rather than a frame pump

I generally use the spare tube first. Sometimes something goes wrong. Maybe you damage the valve while trying to inflate it with your mini pump. Maybe a bit gets pinched in the tire bead. Maybe you didn't remember to get the shard of glass or whatever out of your tire. It's not very likely that you'll get a second flat randomly down the road (though it can happen), but there is a good chance that you get a second flat that is directly related to the first flat.

So why not go to the patch first and not carry a tube? Well, it's more of a hassle on the road. If it's raining making a good repair can be tricky. And some things just aren't patchable.

For me, faster to replace tube than patch. Patch in case of multiple failures. Spare tube also useful for major tube failure (splits) too big to patch.

^^^^^^ +1 on what everyone else already said - multiple failures, bad valve stem, Ability to patch without removing the tube/tire

I've often though about getting one of those myself. Have you heard good things about them?

I had it happen just a month or two ago. It was dark and I couldn't find what had caused the flat. I replaced the tube and got maybe 30 yards before I flatted again.

After getting more light on the subject I found a sizable gash in my tire (that was probably bigger after the second blowout). I had to boot it to get home.

The other reason to carry a patch kit along with a spare tube is to be able to help out a fellow rider.

No; coworkers have come to borrow my pump when their CO2 thing has malfunctioned. But they're so small!!!

I wish I had a bus that follows my commute route.

Spare tubes are much quicker to change, but bulkier, than patch kits. Carrying a small patch kit provides a way to keep riding when you encounter a second flat.

I carry both. For my commuter bike, I usually replace the tube, and patch the old one. That way, I have a spare for the ride home. Also, there are times when I can't find what caused the hole. So, I hope it was just one of those in and out type of punctures. But there have been times when the cause was there, but just under the casing, so later another hole in a tube. With a patch kit, I can repair this and go on.

I use CO2 for my go fast bikes and my fixed gear. For my daily commuter and tourer bikes, I use a frame pump. I have never had a problem with the CO2. There is one problem though, as with my answer above, if you repair a tube but didn't get the cause fixed, you could end up with another flat. Unless you have more than one cartridge, you are out of luck.

I like how little room they take up. I can put it in my saddle bag. I don't need to put it on the frame, so more room for water bottles.

Thanks for the info. You too HardyWeinberg

If conditions are favorable, i.e., ample time, comfortable weather, light, safe surroundings, obvious cause of flat (nail in tire visible) I'll happily patch the hole without removing the wheel and go merrily on my way, too.

The patch kit is to help stranded cyclists who didn't bring their own. The spare tube is for my own flats.

Cause its nice to have that little extra just in case. Its saved my ass more than a few times when I didn't feel that little wire that caused the first flat only to have it cause another. In many cases it still faster to patch it than to hop on the bus too...if a bus comes that way.

I always carry both a spare tube and a patch kit, and both a CO2 cartridge and a frame pump. The first flat gets a new tube and CO2. And I can be back on the road in under 5 minutes. The second and subsequent (yes, it happens) get a patch and a pump. By that time, I'm already going to be late, so I might as well call ahead and take my time.