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I am completely new to riding bikes and know that are usually filled with air but nowadays some people fill them with Nitrogen instead.

I don't know why they prefer to fill their tires with nitrogen as it is more costly than filling them with air.

What are the benefits of filling tires with Nitrogen?

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possible duplicate of Is there a way to fill your tires with nitrogen? –  Neil Fein Dec 17 '13 at 7:37
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@NeilFein The question was how and my question is why? –  JqueryLearner Dec 17 '13 at 7:53
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The advantage of Nitrogen - your bike accelerates faster and has reduced rolling resistance.... because your wallet is so much lighter....... –  mattnz Dec 17 '13 at 8:45
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The advantage is that it makes money for the guy who sells the nitrogen. It also give stupid rich guys something to brag about, when they bore of talking about their carbon frame, et al. –  Daniel R Hicks Dec 17 '13 at 12:02
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Here's the Straight Dope. The biggest advantage is less chance of fire if your brakes overheat going downhill. –  Daniel R Hicks Dec 17 '13 at 17:21
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4 Answers

There are some compelling reasons for filling vehicle tires with pure nitrogen in performance situations, but for bike tires it's just snake oil. There aren't substantial enough temperature fluctuations in a bike tire to justify the pressure consistency argument.

It's also worth noting that the air you breathe and fill your tires with is more than three-quarters Nitrogen, so this isn't as special as it may sound.

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more than 3/4 nitrogen, unless things are very different up there in the northern hemisphere. 78% nitrogen, roughly. –  Mσᶎ Dec 17 '13 at 20:39
    
@Ӎσᶎ - There's a higher proportion of hot air the closer you get to Washington. –  Daniel R Hicks Dec 17 '13 at 21:24
    
I looked for a paper on the change in nitrogen concentration with average air temperature but couldn't find one. Do you have a reference? –  Mσᶎ Dec 17 '13 at 21:53
    
@Ӎσᶎ d'oh! Yup misremembered on my percentages. Will edit. –  joelmdev Dec 17 '13 at 22:05
    
@Ӎσᶎ that was certainly a joke from DanielRHicks –  joelmdev Dec 17 '13 at 22:06
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There are several advantages, most of which apply only marginally to bicycles. A nitrogen seller lists all of them, other sites list pros and cons. The key thing is that it's not about adding nitrogen so much as reducing oxygen, water and other gases.

  1. Nitrogen molecules are larger than water, oxygen and most others, so they percolate through tyres more slowly. This means tyres stay at a usable pressure longer. This is the main benefit that a cyclist will see.

  2. Nitrogen changes pressure with temperature slightly less than water does. But bicycle tyres stay close to ambient temperature almost always.

  3. Nitrogen is less reactive than oxygen, so your tubes will last a little longer. But since tubes normally fail due to punctures rather than oxygen embrittlement it's going to be tricky to measure.

Note that the nitrogen in a bicycle tube will not be in contact with the rim, so the silly motorist argument about less rim corrosion doesn't apply to bicycles at all. In compensation bicycles get a much simpler change-over: just deflate the tube, squeeze all the air out of it, then inflate it with nitrogen. No need for repeated inflate-purge cycles.

But remember that the difference is only in the 20% of the molecules that you've changed from "other" to nitrogen, 80% are nitrogen in both cases.

Also, due to the difference in percolation rates, over time the air in your tyres will slowly become more nitrogen-rich (the other gases percolate out faster than the nitrogen). If you get no punctures, after a few years your tyre might contain over 80% nitrogen!

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On the morning of triathlon competition, when sun comes up and air became hotter, you'll hear blowing tire every several minutes over racks with couple thousand bikes. So, if you don't want surprise in the race day, you can use dry nitrogen or even dry air for tires.

Last year my tire blew up on the hot intersection on red light also.

I don't think if there any performance advantage using it.

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The biggest advantage to filling your tires with Nitrogen is consistency.

Air pressure fluctuates based on temperature, whereas Nitrogen fluctuates to a much much lower degree. http://www.popularmechanics.com/cars/how-to/repair-questions/4302788 While this article is talking about car tires, the principle is the same. People who ride competitively can have an advantage with Nitrogen simply because the pressure is always where they want it. Also, if you ride your bike a lot in many different weather conditions, Nitrogen can save you money in the long run since your tires wear slower (assuming you always keep the tires at the ideal pressure).

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You'd have a hard time convincing me that any of that was "significant" -- that the effects were even measurable. And even if you do manage to reduce tire wear slightly you can buy a lot of tires for the $1000+ that a nitrogen generator costs, or the $10 a pop service stations charge. –  Daniel R Hicks Dec 17 '13 at 17:20
    
Yeah, that's a pretty hard sell considering that the earth's atmosphere is already 78% nitrogen. You're much better off filling your tires to the proper pressure before each ride vs. having the incorrect pressure of nitrogen because of the time and cost constraints of going to the service center every time you want to top up your tires. –  Kibbee Dec 17 '13 at 17:49
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protected by Gary.Ray Dec 17 '13 at 17:58

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