It's really hard for me to believe you are only getting 2.5psi of growth on N2. I get a lot more than that -- pretty much like air -- but I'm also NOT careful about bleeding the tire, and I use a water-based mount lubricant.
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It's really hard for me to believe you are only getting 2.5psi of growth on N2. I get a lot more than that -- pretty much like air -- but I'm also NOT careful about bleeding the tire, and I use a water-based mount lubricant.
That's what it was, I used my oven and my second rim with a power one race on it. I used the same pressure gauge and was very careful to get the temps and times as even as possible. I still had growth. That tire has been on the rim since cresson, so I'm going to do the same experiment after I swap out my 250 tires, so they'll still have some seating wax goo. See if that makes a difference.Quote:
Originally Posted by Jim Dugger
how long did you hold it at each temperature to allow the temp. and pressure in the tire to stabilize? in that video I posted, they did pretty much the same thing (1 hr @ 80c...ya, ya, it was a car tire/wheel, but that shouldn't matter) and they had nearly identical pressure rise.Quote:
Originally Posted by Kasey Lewis
30 min, after 20 the temp gun read no change so i figured that would work ok. Same for both. I was expecting a bigger differential on the nitrogen too, we'll see after a fresh mount.
Nitrogen 24psi at 90f, 27.9psi at 160f and 29.8psi at 205f
Shop Air 24psi at 90f, 27.3psi at 160f and 30.5psi at 205f
On an EX250 with a Pirelli tire. So now i'm really confused. I'll keep using Nitrogen just because i don't have to start my compressor, the bottle is easier, but the difference on that tire was minimal. Yay experiments with conflicting outcomes!
There's another variable you haven't identified yet. Cool experiment though.Quote:
Originally Posted by Kasey Lewis
Well, what s the other variable?Quote:
Originally Posted by Mitch Williams
I'm retarded? I don't know really. It's not a lab setting, but I kept things similar. Different tire On a different rim, but I can't explain one vs the other. If anything I would have expected less growth on a smaller tire/rim. It's interesting, and ill play with it some more to see if i can find out.Quote:
Originally Posted by Jeremy Harvey
Well gee Mr. Wizard.......if you do the same experiment twice and get different results, there must be another variable. It's not my experiment with my conditions, so I have no idea what is different, but something obviously is or the results would be the same. He's a smart guy......he'll find it.Quote:
Originally Posted by Jeremy Harvey
Quote:
Originally Posted by Kasey Lewis
Quote:
Originally Posted by Kasey Lewis
Hey now, there's no need to go calling names here...although I thought Mr. Wizard was about the coolest TV show around when I was a kid! I took your comment about another variable to mean you had identified what it was, and I was curious because I don't know what it is.Quote:
Originally Posted by Mitch Williams
However, I took the two different experiments as two different tire/rim combinations. The first one being a tire that Kasey had recently mounted (I don't bike & tire) and the second one250 tire that had been mounted for several weeks. If it is the same tire/wheel combo, then I'm not sure what variable could be...any number of things: starting temp of the tire/rim, preheat time of the oven, time of each tire at a specific time in the oven...but I figure Kasey has that stuff nailed down, as he seems pretty methodical to me.
The one thing that does seem consistent for Kasey, is that shop air gains more than Nitrogen, but the percent gains and the ratio of Air/Nigrogen gain is quite different.
Exp 1: N gain = 10%, Air gain = 33%. Gain ratio of A/N = 3.2:1 (@205F)
Exp 2: N gain = 24%, Air gain = 27%. Gain ratio of A/N = 1.2:1 (@205F)
For whatever reason, the Nitogen gained a whole lot more, percentage wise, in the second experiment. Air gain percentage is almost close enough to call it within what I would estimate error tolerance to be.