What is the difference between the cartridge bought in a bike shop for $2.50 and the ones bought at Wally World at 15 for $8.50, that power paint ball guns?

The ones at the bike shop fit your tire pump and are calibrated according to the pressure you want in your tire. The ones at Wally World are for powering paintball guns et al.

The ones a wm are not threaded and you need an inflater like this one: https://www.nashbar.com/bikes/Product...9_10000_201460.

I've heard that the ones at the bike shop don't have lubricant in them. The ones for paint ball and CO2 guns have some oil in them to lubricate the mechanisms. I doubt the lubricant would hurt anything anyway.
I don't know, personally I wouldn't use a CO2 inflator except in an emergency. Pumps work great for me and I don't like creating the waste cartridges.

I have had great success with CO2 inflators and will never go back to a frame pump. I carry three cartridges and have never needed even two in a single ride. If I were to go on a century ride, I would carry four cartridges. As for the waste, the cartridges are recycleable.

I never thought there was any difference at all. Excepted the threaded ones have threads cut into them.

I've used el cheapos exclusively. A box lasts a long, long time.

I don't think there is any difference in the unthreaded cartridges from Walmart and the unthreaded ones sold in bike shops.

I have been using the Walmart cartridges for years without a problem. So if there is a difference, it hasn't be a factor in performance.

One cartridge (12g) fills a skinny road tire nicely. Now if you are using CO2 for a mountain bike size tire, you may need the bigger capacity threaded cartridges to fill the tire adequately.

One nice thing I saw on some unthreaded cartridges at a local bike shop is that they came in a thin slide off foam pouch, so the cartridge wouldn't clank around in my seat bag.

Dan

Ding Ding! We have a winner!

No difference at all. Buy a combo pump/CO2 like the Genuine Innovations Second Wind and you have a pump for the purists and CO2 for those "gotta fix it quick" moments. Advantage of the pump is also that you can add a small amount of air to find a hole in a tube.

Pump I listed will take threaded or unthreaded cartridges. Crosman CO2 cartridges are unthreaded. Threaded cartridges will take a shraeder valve cap to keep them from getting beat up in a bag.

I've never had any trouble with a frame pump. Honestly, I've never even seen a CO2 inflator except in pictures.

Recycling isn't the same as not using in the first place.

Folks who care about recycling should buy a bike made of bamboo instead...

That said, CO2 enables me to inflate an aero wheel with valve extenders to 100 psi with no problem at all... it took less than a second. When I got home, I used the same cartridge (16g) to successfully inflate the rear wheel of my trainer... just to check if it still has anything left.

Wow. So nobody who rides a normal bike cares about recycling? What color is the sky on your planet?

No difference. I tried to notice the oil "claimed" to be in the ones used in air guns by spraying one onto a white paper towel. I did not see anything.

Thanks to all who replied. I use a Serfas dual pump: hand pump and co2 inflator combined. It also has a handy gauge built in. Being somewhat frugal, I could not see spending $2.50 per unit for genuine Austrian co2.