Tyre pressure and altitude

[Imtb]

I noticed having pumped my tyres up in Pietermaritzburg to 2.2 that at the end of the Thrombi Super Classic in Underburg (higher altitude) my tryes were really hard - probably closer to 3 bars. Would an altitude change have made the difference as there was no real difference in temperature. If that is the case, those coming up from Durban or down from JHB for the Sani2c had better check tyre pressure at the race rather than before you leave for the race. Imtb2008-02-18 01:15:00

[Cois]

 If we go to the seaside we don't worry about pressure in the wheels.  But upon your return you must let out some air.  Lost a few tires one year.  And yes it is called science

Cois2008-02-18 01:26:19

[Imtb]

 

A mate sent me this in response to my question - problem solved!!

 

If you go onto the website there is actually a fantastic service they run that SMS's you the suggested tyre pressure (STP) for a particular section of the race. How it works is :<?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

You register your cell phone with them.

Their computer programme pin-points (via trig calculations) where you are.Thanks to the input of the finest Google Earth technicians and barometers tagged onto the ears of local Dairy herds they are able to ascertain the exact ambient Mb's of your valve cap.

Based on pre-entered data posted by race organisers the riding technicality of that section is also taken into account.

Simultaneous to this a GPRS connection is made to Durban International Airport Weather Station to give the exact forecast for the next 5 minutes.

With the help of the hydrology dept at UKZNP, probes have been placed every 500 m that give an exact reading (with a 5 second delay!) of the relative moisture content of the soils at 3cm depth. Correlated to your pre-entered Statistics (weight, riding style, competency and tyre size) all this information is crunched at the Shuttleworth Computer Complex in Mid-Rand. A tyre pressure factor is then SMS-ed to you.

As a rider you then multiply this factor by the number of doughnuts consumed at breakfast divided by the amount of seconds spent in the schmitter that morning. This is your specific STP!

You must then stop. (preferably off the track) apply your Pocket Pressure gauge (handed out at registration-one per team!). Due to the built in "Blue-tooth" technology of the gauge it with interface with your cell-phone and automatically reduce the tyre pressure if required.

If STP is higher than your gauge measure a VOIP MMS Sound Byte will announce "Vok Dit" ... and this is your cue to get back on your bike and carry on riding!

Imtb2008-02-18 05:38:32

[porky]

 

A mate sent me this in response to my question - problem solved!!

 

If you go onto the website there is actually a fantastic service they run that SMS's you the suggested tyre pressure (STP) for a particular section of the race. How it works is :<?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

You register your cell phone with them.

Their computer programme pin-points (via trig calculations) where you are.Thanks to the input of the finest Google Earth technicians and barometers tagged onto the ears of local Dairy herds they are able to ascertain the exact ambient Mb's of your valve cap.

Based on pre-entered data posted by race organisers the riding technicality of that section is also taken into account.

Simultaneous to this a GPRS connection is made to Durban International Airport Weather Station to give the exact forecast for the next 5 minutes.

With the help of the hydrology dept at UKZNP' date=' probes have been placed every 500 m that give an exact reading (with a 5 second delay!) of the relative moisture content of the soils at 3cm depth. Correlated to your pre-entered Statistics (weight, riding style, competency and tyre size) all this information is crunched at the Shuttleworth Computer Complex in Mid-Rand. A tyre pressure factor is then SMS-ed to you.

As a rider you then multiply this factor by the number of doughnuts consumed at breakfast divided by the amount of seconds spent in the schmitter that morning. This is your specific STP!

You must then stop. (preferably off the track) apply your Pocket Pressure gauge (handed out at registration-one per team!). Due to the built in "Blue-tooth" technology of the gauge it with interface with your cell-phone and automatically reduce the tyre pressure if required.

If STP is higher than your gauge measure a VOIP MMS Sound Byte will announce "Vok Dit" ... and this is your cue to get back on your bike and carry on riding!

[/quote']

 

 - I had a good chuckle, I am dying to see the replies to that comment.