It's cold out there

My one scientific contribution to the forum. The windchill factors encountered at the moment throughout the UK are pretty harsh and even more so when on your trusty steed. This is just a quick reference diagram (presented here in Celcius for your digestion) that shows just how cold it can get being on a bike. The calculations follow the current JAG/TI model being used for effective calculation and are obviously an approximation based on the average body size, shape and type for a typical US citizen (no jokes please). It also assumes that the individual is at rest and not working hard to control the bike through a chicane or group of homicidal taxi drivers.

Still, it's a pretty good indication.

Yep that figures!

Nice post Matt, is it possible to have the figures for -1 and -2?


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What if the wind is 20mph and you're doing 40mph? Would you add them together to get 60mph wind chill, or does it depend on the direction of the wind? i.e. would a headwind chill you more than a tailwind?

Originally Posted by wyrdness

What if the wind is 20mph and you're doing 40mph? Would you add them together to get 60mph wind chill, or does it depend on the direction of the wind? i.e. would a headwind chill you more than a tailwind?

pardon ?

Not really looked into the other figures (-1,-2 etc...) but the equations are all pretty linear - take an educated guess and you won't be far wrong.

As far as the total wind speed goes, it assumes an 'effective' windspeed. This means that if you are doing 40 into a headwind of 20 then the average effectve speed would be up to about 60 or so. Funnily enough, this does not translate in the opposite direction, mainly because of the way low pressure builds up at your back at speed. Therefore if it were a 20 MPH tailwind, you would not experience an effective 20 MPH wind - it would most likely be more than that.

Also, taking into account sidewinds would be a nightmare because of the inherent number of variables introduced - you can do the math, not me!

Originally Posted by wyrdness

What if the wind is 20mph and you're doing 40mph? Would you add them together to get 60mph wind chill, or does it depend on the direction of the wind? i.e. would a headwind chill you more than a tailwind?

Generally, I find that a nice little hit of white widow chills me quite nicely thankyou...

Are these calculations made based on wind chill felt on bare skin or does it matter.

Originally Posted by dclifford

Are these calculations made based on wind chill felt on bare skin or does it matter.

Yup - but that doesn't mean you don't feel it...

The calculations take into account heat transfer due to exposed skin on the face only. It does not take into account any measure of thermal insulation you might have (that rubber undersuit for example...) nor does it take into account heated grips or such.

A good expaination fo the calculations and definitions is available here: http://www.nws.noaa.gov/om/windchill...ossary.shtml#1

The table is quite good but don't bother with the formula they display - it's rubbish!

I ride is quite cold weather with headed gear, I have found my limits at about -15°F/-25°C, at 60mph, wind chill is about -50°F/-45°C

http://www.crh.noaa.gov/pub/metcon.shtml