I just ordered the Ultra Flate Plus Co2 dispenser. I have the small dispenser that only accepts threaded cartridges. I am getting tired of buying the expensive threaded 16 g carts. So my theory is that with this new dispensor, i will be able to use the mini pump to pump up to about 30 lbs or so, and then use some of those cheap threadless cartridges for air rifles available at Walmart. Anyone else do this?

I am pretty new to the road, and always just used mini pumps on my MTB's. I have to use the mini on my road bike to make the tube take shape so i can insert it anyway. Why not just pump it up a little with the minipump and then top it off with the cheap threadless carts?

No reason not to. A bunch of people on this board do what you're thinking of doing and it works well for them.

Let's not forget highschool chemistry...


The amount of pressure in the end for which you can achieve with a certain size cartridge will be a function of the size of your tyres and the size of the cartridge. That is to say that if a 12g cartridge is guaranteed to inflate a 700x20C tyre to 100PSI and you manually inflate with a pump to 30PSI before using the cartridge, you will not necessarily get to 130PSI at the end. Once pressure equalises at both ends then you're done.

Didn't you mean to say "Let's not forget highschool physics?"

Actually I first learned my gas laws in my highschool chem classes although I do recall some of my physics classes touching on them a bit too. I don't remember any of my college physics classes dealing with gas laws though but my freshman year chem class did.

The only gas laws i learned in high school were working at the local filling station. Anway, there should be no risk of bursting the tube with this method should there? I can't think you could over inflate with this method.

I learned my PV=nRT in High School Chem also. Then, I expanded on it during my College Chem days.

mscycler

I'm one of them.

As long as your tube/tire combo is rated to take the max psi of the cartridge your using (a 16g cartridge will usually get a 700x23 tire to about 120 PSI or so), you should be fine. If you are using a 700x28 tire thats only rated to 95psi, you may have problems though.