wilfried

Bike share in New York reportedly fills their tires with nitrogen. They say so here (scroll down to where they mention tires):

https://citibikenyc.com/meet-the-bike

I'm not sure I see the point.

DiabloScott

I'm guessing an influential somebody's relative owns a compressed gas distributor business.

Eds0123

Oh yes, great suggestion, another great advantage would be no need for the studded tires for winter icy roads. The heat produced by Radon radiation instantly melts and evaporates the ice under your tires ... :-)

blacknbluebikes 

empirical research:
https://www.nitrofill.com/documents/i...port101807.pdf

Interesting, but if you read into it carefully, I don't think the marginal benefits are really there for cyclists.
They're measuring benefits for fleets of trucks doing 2500 miles a week; static test losses of a few psi over hundreds of hours. I'm not suggesting that this translates directly, but certainly doesn't look "tasty" for us...

mrodgers

It is my understanding that automotive race teams use nitrogen in their tires to give a more consistent and accurate reading of tire pressure when the tires heat up from 200 mph speeds.

I don't think this is an issue with neither car tires, nor bicycle tires.

DogBoy

I think I'll just buy the green valve cover so all my friends THINK I have nitrogen in my bike tires.

bjorsa

Concerning the CO2 global warming aspect, we are talking about ridiciously small volumes here. Considering that the air you exhale contains up to 4% carbon dioxide, you probably will add more to the greenhouse effect by simply breathing as you take care about your tyre business. And the CO2 found in the cartridges probably (well ok, likely in my eyes FWIW) isn't the lucrative incentive for the industry behind it - this snip is from the Universal Industrial Gases website:

"The concentration of CO[SUB]2[/SUB] in air and in stack gases from simple combustion sources (heaters, boilers, furnaces) is not high enough to make carbon dioxide recovery commercially feasible. Producing carbon dioxide as a commercial product requires that it be recovered and purified from a relatively high-volume, CO[SUB]2[/SUB]-rich gas stream, generally a stream which is created as an unavoidable byproduct of a large-scale chemical production process or some form of biological process. In almost all cases, carbon dioxide which is captured and purified for commercial applications would be vented to the atmosphere at the production point if it was not recoved for transport and beneficial use at other locations."

https://www.uigi.com/carbondioxide.html

Andy_K 

Yep.

I did some calculations using the figures on the Prestacycle site (which sells a Nitrogen inflation system) for the rates at which oxygen and nitrogen escape. Starting from a mixture of ordinary air, you'll have nearly pure nitrogen (plus residual moisture) when the tire slips to about 70% of its initial psi. If you wait until then to refill, the newly refilled tire will be about 93% nitrogen and will hit pure nitrogen at about 90% of psi. Refill again at that point and you'll be at 98% nitrogen. From there, vigilant re-inflation will keep you very near pure oxygen using just a simple floor pump. The key is to let it drop to 70% before the first re-inflation.

Of course, most people probably let their tires drop to around 80-90% of ideal psi before topping it off, so they're condemned to always hover at around 90% nitrogen.

Yes, I'm a geek.




To offer something a bit more practical, finding tubes that minimize air leakage is probably a much better investment than inflating with nitrogen.

JohnJ80

I'm very particular about the gas with which I fill my tires. I've settled on a 78% nitrogen blend. I use it in the cars too.

j.

rm -rf

I always make sure it has .9% argon in the mix. That's critical.



CO2 exhaled by an average person: 900 grams per day, or average 37 grams per hour. So a 16 gram CO2 cartridge is the equivalent of 25 minutes of breathing out, and even fewer minutes when working hard.

Woah, I didn't expect 900 grams per person per day. But I also didn't know that air is 7.5 pounds per cubic foot. That's way heavier than I expected. No wonder it's hard to go fast on a bike, the rider has to shove all that weight of air out of the way.

gunner65

rm-rf

Thanks for that post. I was belly laughing at the his original CO2 post. Maybe if he stops breathing he will greatly reduce his carbon footprint.

unterhausen

N2 is dirt cheap, so the fact that some people charge extra for it is goofy. I suspect they release a considerable amount of it back into the atmosphere when they pull it out of air. At work, I actually pay more to rent the tank for a month than I do for the gas, it's something like $4. I imagine that anyone that has to carry a bottle of gas around to fill up bike tires with would do pretty well using N2, you can go get a bottle and it will last for quite a few tires. Nobody bottles dry air.

Saving Hawaii

You say this and yet we get occasional deliveries of cylinders full of dry air at my work.

prathmann

I think you missed the " x 10 ^-2" at the top of the table.

ThermionicScott 

Nitrogen gas has undeniable benefits for draft beer. Bike tires, less so. Besides, what's the environmental impact of manufacturing, filling, and recycling those stupid little canisters? Quit whining and use your pump.

walrus1

Ah yes the good ole if it works for nascar it must work for my car crowd.

wilfried

Thinking about this for another half a second, maybe it does make sense. I don't quite follow all the discussion about just how much a difference nitrogen makes, or why, but even if the difference is a small incremental improvement, it might make a difference when you're trying to maintain 4000+ bikes and keep them on the road. You'll want to minimize having to pump those 8000+ tires in whatever way you can. And on the scale of thousands of bikes, the cost of using nitrogen might not be that high.

Given how much racing drives the cycling market, there's plenty of the "if it works for Lance it must work for my bike" crowd.

Bike Gremlin

Schwalbe tubes work wonders for me. Their tyres less so, but tubes are very good.

Andy_K 

I love their tires. I've got Marathon Supremes on three of my bikes, Rocket Rons on another and Marathon Pluses on my wife's bike. Oddly enough I've never tried their tubes. I don't see them in the local shops I visit. I might have to order some to give them a try.

i like Conti tubes.

wphamilton

Regarding the environmental aspect, I realized that I didn't know where it actually came from, to put into those little cylinders. From what I can find, it has to start as a high volume CO2-rich gas, which is generally a byproduct from a large-scale chemical process. In other words, released into the atmosphere if it wasn't bottled up for bike tires. So I don't think we need to feel guilty about contributing to the greenhouse effect.

I take it with a grain of salt since my sources were all from the commercial end, such as Bulk Liquid Carbon Dioxide > Air Liquide UK but it sounds plausible to me.

cyccommute 

While your facts are correct, your interpretation is faulty. Not all carbon dioxide is equivalent. The 900g per day that the average person respirates is carbon dioxide that is on a short rotation. It comes from the food that you ate in that day which came from plants and/or animals that were alive a few days to weeks to months ago. The CO2 you breathe out per day is used relatively quickly by the plants around you. The impact on the global climate of animals breathing out CO2 is small and easily absorbed by the environment. Any excess CO2 from that animals might produce or that plants might produce when burned is absorbed by plants, buried and eventually fossilized to remove it from the overall planetary environment.

As bjorsa points out above, the CO2 in a cartridge isn't recovered from the atmosphere. It is obtained from processes that produce large CO2 streams. That means the fossilized carbon that was removed from the planetary environment millions of years ago has to be dug up and reintroduced to the environment. Not using a CO2 canister does, indeed, reduce your carbon foot print. It may not reduce it much but it is a reduction.

Let's also not forget...or you may not know...that CO2 is much more permeable than air in a bicycle tire. It's an emergency fix only. The rate of diffusion is influenced by the internal pressure but, generally speaking, a CO2 filled tire will be flat in 12 to 24 hours.

Finally, you need to reread that chart. That 7.5 (lb/ft3) x 10-2. In other words, a cubic foot of dry air at sea level weighs about 0.075 pounds per cubic foot.

JohnJ80

That would work. Less carbon footprint is a good thing, right?

Personally, my latest mission is reducing bovine flatulence which is a major source of methane, a greenhouse gas.


J.

himespau 

The thing is, though, if he stops breathing, eventually, he'll start decomposing. And that'll release even more CO2 into the atmosphere.

JohnJ80

<sigh> This is such a difficult problem.

I've not been worried about CO2 I put off by breathing, but wouldn't then exercising be wrong for the environment? So much for cycling.

J.