Heated Grips and Waterproof Gloves

We had a customer recently who wanted to return a pair of gloves because he found them not to be properly waterproof.

We had them tested, and the membrane didn't leak; but what we didn't realise initially was that he had been riding in heavy rain with his heated grips turned up high.

It would seem, therefore, that there are bikers out there who don't understand, or even know about, this particular phenomenon.

First things first. Some people discuss this topic in relation to Gore-Tex. Well, Gore-Tex is just a brand of membrane, albeit a very highly regarded one. The principle, though, applies to all waterproof membranes, and therefore to all waterproof gloves.

A membrane contains millions of little holes. These holes are too small for water to pass through, so the rain is kept out. But what the holes do allow is for vapour to pass through, from the humid side to the dry side.

This is important for keeping dry because, if the humidity could not escape, we would feel wet from the inside, as the body is always generating heat, and thus perspiration.

Now when you use heated grips, your hand becomes warm and dry. When your hands are warm and dry and it's raining, the outside of the glove is wet and moist, and the outside of the membrane is humid, whilst the inner side of the membrane is dry and warm.

And so the process is effectively reversed, and the extermal moisture passes from the outside of the glove to the dryer inside.

As a biker, therefore, you are implicitly faced with a choice. You can ride with cold but dry hands by turning the grips off. Or you can ride with warm but wet hands. Personally, I've always preferred the latter. After all, there's nothing unpleasant about a warm bath!

So if, over the winter, you find that your supposedly waterproof gloves are not as waterproof as you had expected, it might be down to your heated grips.

And not, as our customer thought, because he was riding so fast that his gloves could not cope with the pressure!

Despite his protestations, his gloves were very much fit for purpose. He just didn't realise how his gloves worked.

It's exactly the same reason, by the way, that you need to wear breathable, wicking base layers under your technical jacket and trousers. If you wear cotton garments, your skin won't breathe and, again, the inside of the membrane can become dryer than the outside. The membrane will effectively be reversed, and the moisture from outside will pass as vapour through the membrane into the garment, and you'll end up feeling wet.

Anyway, now you know.