the weight of air in our tyres
Moderator: robbosmans
I couldn't believe air does add weight to the bike, so tested it out myself, and Bike with both real 25mm tyres at around 90psi vs complete flat tyres made a whopping difference of 20gr! Not that you could win something in real usage, but it's a trick if you are just a few gr above 6kg and really want a scale pic at sub 6kg f.ex
Current bikes:
Scott Addict Premium Disc 2018
Scott Addict Orica Greenedge 2015
Retired:
Canyon Endurace CF SLX 2016
Canyon Ultimate CF SLX 2013
Scott Addict Premium Disc 2018
Scott Addict Orica Greenedge 2015
Retired:
Canyon Endurace CF SLX 2016
Canyon Ultimate CF SLX 2013
Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓ Broad Selection ✓ Worldwide Delivery ✓
www.starbike.com
Also to note is if you are at altitude and pump your tyres up to the same pressure as at sea level. The bike will "weigh" more at sea level than at altitude.
Hambini Aeronautical Engineer, Polluting YouTube since 2016 - views expressed are my own...
-
- Posts: 20
- Joined: Thu Dec 29, 2016 5:16 pm
- Location: Bentonville, Arkansas USA
It isn't so much a change in weight as it is a change in density... You are adding more air molecules into the relatively same volume of space.
Sent from my HTC 2PST2 using Tapatalk
Sent from my HTC 2PST2 using Tapatalk
TheKaiser wrote:TeslaOsiris wrote:It isn't so much a change in weight as it is a change in density... You are adding more air molecules into the relatively same volume of space.
That is a good technical correction and reminder of the physics at work.
No, it's tautologous gibberish. By definition a change in density for the same volume is a change in weight, assuming constant gravity.
-
- Posts: 20
- Joined: Thu Dec 29, 2016 5:16 pm
- Location: Bentonville, Arkansas USA
964Cup wrote:TheKaiser wrote:TeslaOsiris wrote:It isn't so much a change in weight as it is a change in density... You are adding more air molecules into the relatively same volume of space.
That is a good technical correction and reminder of the physics at work.
No, it's tautologous gibberish. By definition a change in density for the same volume is a change in weight, assuming constant gravity.
I think the word you are looking for is "mass", not weight Density is a ratio of mass:volume... Weight is a measurement of gravitational attraction. But what does my tautologous gibberish know? (That's not even a tautology is, FYI)
Sent from my HTC 2PST2 using Tapatalk
TeslaOsiris wrote:I think the word you are looking for is "mass", not weight Density is a ratio of mass:volume... Weight is a measurement of gravitational attraction. But what does my tautologous gibberish know?
Apparently your tautological gibberish doesn't know that we all live on the surface of the earth, therefore when you increase the mass of a bike you increase the weight by exactly the same degree, always. The word 'weight' is equally as valid as the word mass. If there's anything worse than being that pedantic it's being that pedantic and wrong
This applies equally to your original point. Air has weight. Adding more air to tyres adds more weight. This statement is no less valid because the density of the air in the tyres has also increased. It's not a situation where one or the other is true. They are both equally true at the same time.
Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓ Broad Selection ✓ Worldwide Delivery ✓
www.starbike.com
TeslaOsiris wrote:964Cup wrote:TheKaiser wrote:TeslaOsiris wrote:It isn't so much a change in weight as it is a change in density... You are adding more air molecules into the relatively same volume of space.
That is a good technical correction and reminder of the physics at work.
No, it's tautologous gibberish. By definition a change in density for the same volume is a change in weight, assuming constant gravity.
I think the word you are looking for is "mass", not weight Density is a ratio of mass:volume... Weight is a measurement of gravitational attraction. But what does my tautologous gibberish know? (That's not even a tautology is, FYI)
I wonder why I said "assuming constant gravity" in my original post? And it is a tautology, because you are saying the same thing twice. Adding more molecules into the relatively same volume of space [sic] is indeed a change in density which is precisely as much a change in weight. They are (for a constant volume in constant gravity) exactly the same thing. (Even more amusingly, and tautologically, our common measures of mass are also measures of weight at Earth-normal gravity.)
[/pedant mode]