WATERPROOF JACKETS

A waterproof jacket is an investment, and while it’s broadly true that you get what you pay for, it’s still entirely possible to make an expensive mistake. So, what should you look for?

Brands quote different waterproof ratings for their jackets, which seems counter-intuitive – surely something is either waterproof or it isn’t? It all comes down to just how much water a jacket can withstand. The hydrostatic-head figure, in millimetres, is worked out by seeing how high a column of water a material can support before it fails and starts to let moisture through. The British standard for something to be designated waterproof is 1,500mm (ie. it can support a 1.5m-high column of water). This would seem guaranteed to keep you dry, but a hydrostatic-head test doesn’t replicate driving rain or the additional pressure created by a pack. In reality, a 1,500mm fabric is only water-resistant. Most fully waterproof jackets will have a rating of at least 10,000mm and up to 30,000mm. Some brands – GORE, for example – don’t quote hydrostatic heads because they test in real-life conditions rather than in the lab.

If you spend all day on an uplift, breathability may not be a big issue, but if you turn the pedals in anger for any length of time in a waterproof you’ll likely get warm, in which case you’ll want to pay attention to the moisture-vapour transmission rate (MVTR). Expressed in g/m , this shows the amount of moisture vapour (sweat) that’ll pass through the fabric in 24 hours. As a guide, 10,000g is a good base level, 20,000g is for active use and 30,000g