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Tyre pressure when loaded.



 
 
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  #11  
Old October 28th 14, 11:51 PM posted to rec.bicycles.tech
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Default Tyre pressure when loaded.

On Tuesday, October 28, 2014 6:46:11 PM UTC-4, wrote:
digthruthis

https://www.google.com/#q=formula:+v... easing+volume


http://www.calculatoredge.com/new/bernoullithm.htm
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  #12  
Old October 29th 14, 12:03 AM posted to rec.bicycles.tech
Andre Jute[_2_]
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Default Tyre pressure when loaded.

On Monday, October 27, 2014 8:47:59 PM UTC, Ian Field wrote:
Are there any published tables or graphs that show how the tyre PSI
increases when the rider sits their weight on the saddle?

Thanks.


Not that I know of, but you can do a simple experiment to answer your question directly. Inflate the tires on the unloaded bike to a baseline pressure in the normal manner. Keep a note of the pressure inside the tubes, front and rear. Load the bike. Measure the pressure inside the tubes again. The difference is the increase in pressure due to load.

***
If you aren't experimentally inclined, you may be able to infer something from the tire drop at optimum pressure.

Try "Optimizing Your Tire Pressure for Your Weight" by Jan Heine, published in Bicycle Quarterly Volume 5, Number 4. It is available to read on the net or to download from:
http://www.bikequarterly.com/images/TireDrop.pdf

The conclusion that Heine came to is that the tube should be inflated so that the tire under full load is depressed by 15% of its vertical sidewall height. This is known as "tire drop". Unfortunately for your purpose, drop is not directly related to increased pressure but, given an optimally inflated tube to start with, it does appear to set an upper limit of about 15%.

***

FOR THOSE INTERESTED ONLY IN ARRIVING AT THE OPTIMUM TIRE PRESSURE FOR THEIR WEIGHT:
Measuring the sidewall and even more the tire drop is tiresome, but the article refered to above includes a graph by Frank Berto from which you can read off recommended pressures for various road and touring tire sizes to suit varying load.

Andre Jute
Relentless rigor -- Gaius Germanicus
  #13  
Old October 29th 14, 12:49 AM posted to rec.bicycles.tech
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Default Tyre pressure when loaded.



http://www.conti-tyres.co.uk/conticy...l_safety.shtml
https://www.google.com/#q=continenta...recommendation
Frank wrote yesterday...I doahn know if then specs are applicable to today's tires.

Using a scientific method as square one s intriguing but there's a lotta material there.

Eyeball and feel for your riding style and environment maybe best.
There are guides embossed on sidewalls 'inflato to 140-180 pounds' so within that range should lie your spot.

Some riders like a bit of contact area squash, some not.
There's a squash area that is both squash and un squash....the patch grips but guides sharply...as least to the rider's perspective.


 




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