I’m looking for a race-day only CO2 inflator that will be both reliable and fit easily in the cutout of a typical disc wheel. I know such a creature exists (I remember reading about it), but don’t remember the model. Nano, maybe?
Steve
Thanks. I thought it was the Nano.
Have you used it? Is it reliable?
Steve
I’ve used their similar inflator, but not the Nano. Also used the Air Chuck, both without issue.
http://www.trisports.com/pumpscosub2sub.html
I believe you get 15% off with ‘XTRI-15’ too.
Kevin
I’m looking for a race-day only CO2 inflator that will be both reliable and fit easily in the cutout of a typical disc wheel. I know such a creature exists (I remember reading about it), but don’t remember the model. Nano, maybe?
Steve
Important question…what tire, or more specifically, what type of tube will you be using this on?
Michelin Pro2Race 700x23 with Michelin AirComp Latex 700x18/20 tube.
Should I be worried???
Steve
Michelin Pro2Race 700x23 with Michelin AirComp Latex 700x18/20 tube.
Should I be worried???
Steve
Yes. I don’t recommend filling a latex tube with CO2. It just permeates WAY too fast to be useful. IIRC, CO2 passes through butyl rubber (a regular tube) about 6X faster than air (mostly nitrogen). Well…CO2 passes through latex ~10X faster than THAT! In other words, it permeates through latex ~60X faster than air through butyl. DOH! Depending on how far you have to go after the repair, you just may find yourself stopping to refill the tire again just because the CO2 is leaking out too fast.
If you plan on using the CO2 for repairing a flat, my recommendation is to pack a butyl tube for the repair.
I generally top my tires off before every ride. So, to be perfectly honest with you, I’ve never studied how long it takes for the pressure in my tubes (butyl or latex) to leak below an acceptable level. Since you’re an engineer and, obviously, have though about this more than I have, I present you with the following problem. Here are the facts…
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This is a race day only emergency solution.
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I only plan on racing up to 1/2-IM distance (in the near future). So, worst case would be flatting just out of transition and having 56 more miles to go. This should equate to a ride time of somwhere between 2:30 and 2:45.
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I plan to carry 16g cartridges.
Q1. I have no idea what sorta pressure a 16g cartridge will pump my tube/tire combo up to. Any idea?
Q2. What do you think the pressure would be after 2:45 with a latex tube?
Q3. Same question, butyl tube?
Your advice is sound (and one I hadn’t thought of). So, regardless of the above, I will take your advice and carry and butyl spare. If I flat, it becomes less about saving seconds (with a latex tube) and more about damage limitation (butyl tube a bit sturdier) anyway.
Steve
I generally top my tires off before every ride. So, to be perfectly honest with you, I’ve never studied how long it takes for the pressure in my tubes (butyl or latex) to leak below an acceptable level. Since you’re an engineer and, obviously, have though about this more than I have, I present you with the following problem. Here are the facts…
-
This is a race day only emergency solution.
-
I only plan on racing up to 1/2-IM distance (in the near future). So, worst case would be flatting just out of transition and having 56 more miles to go. This should equate to a ride time of somwhere between 2:30 and 2:45.
-
I plan to carry 16g cartridges.
Emergency use is great. BTW, I’ve found that 12g cartridges are plenty for a road tire and get them up to around 110 psi, which is pretty optimum. I save the 16g ones for the MTB tires…which have a much greater volume. Plus, I can get non-threaded 12g cartridges pretty dang cheap at K-mart 
Q1. I have no idea what sorta pressure a 16g cartridge will pump my tube/tire combo up to. Any idea?
No idea…why not give it a try and see? I have a feeling it will be more than enough based on my experiences with 12g cartridges.
Q2. What do you think the pressure would be after 2:45 with a latex tube?
Q3. Same question, butyl tube?
Not sure, but it sounds like an easy experiment to try. Just fill your tire with a CO2 inflator, measure the pressure after inflation, and then again after 2:45. You could try that for both tube materials.
For a rough approximation, I know that I lose ~20 psi overnight in my tires with air in a latex tube. So, that’s ~0.8 psi per hour. If CO2 permeates through latex at a rate 10X that, that would be a loss of ~8 psi per hour. So, over the total time of 2:45, you could expect your pressure to be around 22 psi lower than when you filled it. So, if the fill get’s you up to 110 to 120psi, you’d be down to 90-100 psi by the end of the leg. That’s actually not so bad for a HIM, but in an IM, I don’t think you’d want to be losing pressure at that rate.
Your advice is sound (and one I hadn’t thought of). So, regardless of the above, I will take your advice and carry and butyl spare. If I flat, it becomes less about saving seconds (with a latex tube) and more about damage limitation (butyl tube a bit sturdier) anyway.
Steve
Yep…that seems the easiest and most prudent solution. If you’re going to use a CO2 inflator for a repair, it’s best to just pack a butyl tube as your spare.
Gotcha on the non-threaded cartridges being much less expensive. Unfortunately, the Nano (which is the inflator of choice for easy use on a disk) only uses threaded cartridges. So, 12g or 16g doesn’t make much difference $$$-wise.
I found this yield chart. http://www.genuineinnovations.com/yieldchart.aspx It should at least give a good ballpark for tire pressure with the different sized cartridges. Although, it doesn’t take into account tire width and does give a number 20psi lower than you’re reporting. So, it may only give a reasonable ballpark.
As you mentioned, if I really wanted to know, I could just waste a couple of cartridges. But, I’m just trying to get an idea here. And, being superstitious, I don’t want to break the seal on my inflator. I’m afraid it’ll like being used!
I agree with you. While a ~20psi loss isn’t so bad, the smart thing to do would be to just use a butyl spare and hope to never need it. Besides, from talking to you previously on the latex tube subject, I seen to remember that they’re a little less forgiving with installation, too. And, I probably won’t be taking quite the care I would normally take should I flat in a race.
Steve