I was chatting with a friend the other day who’s just getting into biking. He was telling me of his experience with his first flat. No pump, no CO2. He had a patch kit in his seatbag, but realized it was worthless unless he could fill his tire with air, so he wound up walking the bike home — three miles.

“I saw these canisters of CO2 at the bike store,” he said. “Are they any good?”

Here we go again — the endless debate between CO2 and a pump.

Well, I told him, each has its advantages. CO2 takes up just a little space in your seatbag, and you don’t have to carry a pump. Just attach the inflator, stick it on the valve, and whoosh! you’re back in business. He liked that. He thought he’d try it.

But wait a minute, I said. There’s a problem with CO2, too. Sometimes, you misfire it and waste all the gas in the canister. Then, you can find yourself in the same predicament you were in last week.

I told him of a recent A ride from our club, where a guy flatted along a major highway. One of the other guys had several CO2 cartridges — and managed to depressurize all of them. Without inflating the tire. Luckily, another rider in the group carried a pump, and stood by to watch the antics — then stepped in and saved the day.

“It took me probably 10 minutes to pump up a tire to 70 psi,” said guest poster Don Blount in an email awhile ago. “That’s longer than it took to change the tube.”

I’ve been there. It doesn’t take me that long to pump a tire up to 70, or even 90 psi. But those last 10 pounds to 100, to make it roadworthy again — I should be doing some strength work at the gym.

But Don also said he blew a tube with one cartridge, and when he went to use another one on another tube — it was a dud. He thinks he might just suck it up and go back to the frame pump.

At least that’ll get the tire inflated. With a cartridge — I’m guessing 50-50 odds.

My friend went back to the bike store and got a frame pump.