I’ve managed to get my hands on, or rather my “legs in” some of the Pearl Izumi PI DRY fabric. The fabric has every single strand coated with a water repellent coating before weaving into the fabric. So the theory is that the garment can be fully breathable (as breathable as standard dry weather fabrics) whilst providing water protection, avoiding that clammy feeling of waterproof clothing and keeping the rider warm and comfortable. Here’s a short video showing my initial testing with the PI DRY leg warmers:
A few minutes after filming this, I cycled home late on a September evening in the UK. I was warm and comfortable. The leg warmers felt like any other fleece lined leg warmers would. Grippers worked fine and I felt warm and comfortable. Most importantly I felt dry, which just goes to show how water repellent the fabric is after being in the shower! The cut of the warmers is slightly shaped, giving a slightly bent knee. The ankle zips are a nice touch, making them easy to fit over overshoes to prevent the water just running into your shoes.
The water repellence relies on the surface tension of the water, as it beads up and runs off. For most cycling applications where there is a light rain shower I expect this material will keep the user completely dry. Forcing water into the fleece side of the fabric using a shower (or hose pipe) or by submerging the fleece lining for any time does make it look saturated, but the water can just be flicked, wiped or squeezed out of the fabric straight away. It really does dry surprisingly quickly.
So initial impressions are very impressive. Pearl Izumi don’t claim this to be 100% waterproof, they claim that it is “Permanently water-resistant, for all-weather water shedding performance”. The aim is not to prevent the rider from getting wet, but to keep them as comfortable a possible, keeping them dry and sweat free during their ride.
I’ve yet to do a long term test in real UK weather, but I’ll update on this as I test them some more, so subscribe or check back later for updates.