I hate riding the highways in the city, but once I’m away from all those horrible drivers, I love it. One thing I did notice during my first highway ride of the season was a loud booming noise every time I went faster than 80 kph. The faster I went, the louder I got. I didn’t have the problem last year with my previous helmet, so I knew it was the helmet and not my over-sensitive ears.
After doing a bit of searching on the Internet, I discovered the booming is made from air being force up into the helmet from around the neck. The solution is to purchase a sleeve or skirt that permanently attaches to the helmet. However, none offered for sale are made for modular, or flip-up, helmets.
As I understand the science behind attaching a skirt, it prevents the wind from going into the gap(s) around the chin and neck and vibrating the helmet. The air is forced in, with very few areas to escape, so it rattles around in the helmet and basically turns the helmet into a bass drum.
I knew that I didn’t want nor need a perfectly air tight seal around my neck. I put on my helmet and found that I could touch the back of my ear with my fingers. The gap around my jaw line was just as bad, and there was also a large gap at the back of my neck. For a helmet that fit my head so well, it fit also fit very poorly.
I rummaged through some scrap material and found about a metre of polar fleece, which was the remnants of a winter scarf. While polar fleece is not windproof, I hoped it would disrupt the wind flow enough to stop the boom while still let in air to breath and cool my face.
I stitched the fleece onto the helmet’s check pads and along the rather useless wind proofing material on the sides. Once completed, it looked as if there was barely room for my head to hit in to the helmet. But as the fleece was not pulled tight when I stitched it to the helmet, there was enough give in the material for me to move the fleece aside and pull on the helmet.
As an added touch, I put two strips of electrical tape at the rear of the helmet where it meets the fleece. I was a bit suspicious of water running down onto the fleece and thought the tape would help keep the water dripping downwards and not wick into my helmet through the fleece.
I obviously couldn’t attach the fleece all the way around to include my chin, as I wanted to keep my helmet flip-able, if you know what I mean. The fleece tucks neatly under, up and along my cheek pads, thus it is up against the fabric installed on the helmet under my chin. To make sure there wasn’t a gap, I used a few small pieces of weather stripping around the edges.
I’ve been riding with my polar fleece helmet skirt for over a n month and the only time I get the booming sound on the highway is when I forget to pull the fleece down my neck. You see, when I put my helmet on, my head pushes the fleece into the helmet. This doesn’t give it enough wind protection as when it is outside the helmet and against my neck.
I was out last weekend in 38° C weather (in other words, really hot) and riding on the highway. My neck wasn’t any hotter than the rest of me. The fleece doesn’t act as insulation, but as a bit of a windbreak while still being breathable. Rain has caused a bit of a problem, but it is only noticeable when I remove my helmet. The fleece gets damp and it is a bit uncomfortable putting the helmet back on with damp fleece. Water doesn’t run down my neck because of the skirt; however, it my have something to do with my waterproof jacket, but I can’t be sure.
It took me about an hour to cut and stitch the skirt on, which I consider time well infested to get rid of the bass drum sitting on my head