dish type rear wheels

I read on another board a discussion about dish type rear wheels. Someone mentioned that it was possible to make your own and not spend big bucks. This got me thinking and researching and I found these instructions. I'm a pretty good do-it-yourselfer and this doesn't look to complex. I figure if it saves any time / makes me faster it's worth the $20 and hour. What do you think? I pasted the text from the site below but the pictures didn't paste. http://www.biketcba.org/TRICORR/projects/disks/covers.html

Building Plastic Wheel Disks
The whole concept behind covering your spokes is that as the wheel rotates, the spokes are constantly cutting new air. They're thin, but there's so many of them it adds up. At the bottom of the wheel they are essentially motionless for an instant, but at the top they're going twice as fast as the bike! The rear wheel area of a bike isn't exactly the cleanest airflow anyway, but those eggbeater spokes aren't helping things any! By covering the spokes, you allow the air to flow past the wheel. To get the best benefit, the covers should butt up with the brake surface of the rim; but if you have an aero rim, the added benefit isn't too far out of line with just filling in the spokes.

I've been using my spoke cover/wheel disk on my V-Rex for almost a year, and in my estimation it has the best effort to results ratio of all my projects. Unfortunately, the benefit is only obvious at speeds of about 20 mph or greater, so not everyone would benefit the same. With the spokes covered, the ride is quieter, and the speed assist is obvious at higher speeds.

The material I used here is styrene. It's cheap, it's durable, it's paintable. It's the same plastic that's used in those models I put together when I was a kid. It comes in 4x8 foot sheets. The thickness I used is 0.030". That thickness is still strong enough to deflect stones your buddy shoots at you, but only weighs a few ounces for a wheel's worth. Coroplast also works, as does about any relatively stiff film i.e. Lexan, Vivac, ABS, some foams, etc. If you are searching for some other material to use, bear in mind you want it to be lightweight, so 1/4" Plexiglas is probably not a good idea.

I started by measuring over the wheel's dish from the inner edge of the rim to the other side. Every rim is a little different, so I can't help you with the measuring. I can say, err on the large side - you can always cut the disk smaller, but it's tough to cut one bigger or uncut a boo-boo. Compasses that size are hard to find, so I fashioned one out of a length of wire, with a small nail to mark the center of the circle. Any material that doesn't stretch would work - kite string, a yardstick, etc. I marked one circle the size of the rim and one circle for the hub. On the drive side, the inner circle should be slightly smaller than the diameter of your spoke protector, or of your largest cassette sprocket (whichever applies.) One important detail to note, measure both sides of the wheel. The non-drive side is usually dished more than the drive side, and so will use a larger diameter disk. Slit the disk so it will slip over the hub and dish properly. Below is the disk for the left side.

Starting with the left, non-drive side, I slide the disk on the wheel and tape it in place. As I attach the cover with zip ties, I put the tag ends of the zip ties to the inside the wheel. The drive side will have to have the tag ends on the outside, but at least this way leaves the left side as clean as possible. Due to the dish, the two sides of the slit will overlap. That's ok, I just leave them that way. Note where I placed the flap edge of the cover, you can see why below. As an additional detail, when you overlap the ends, tuck in the 'downwind' edge so it won't be scooping air with each revolution.

Styrene is rigid, unlike Coroplast. You can't just punch a hole in it. I used a Dremel with a 1/8" bit. It's smaller than a drill and easier to control. The lowest speed setting was fine as styrene cuts and drills easily. Whatever you do, take care not to nick your spokes with the drill! The plan is to attach the cover to every other spoke, non-drive side first. I started three non-drive spokes away from the valve, that way I can pump up the tire without removing the cover. Below is my first two holes. The zip tie goes around the spoke, with the 'knuckle' on this side, hidden from the airflow. As you can see, I'm drilling near the outer edge of the cover. The edge near the hub will hold itself in place, as long as you secure the cover along the circumference.

From here we move around the wheel, pulling the cover taught and drilling holes for the next zip tie. Don't do them all at once, because you will inevitably suffer from measurement creep, and by the time you're halfway around the wheel, the holes won't align with the spokes anymore. Below, the cover is zip tied in place. I've left a flap for access to the stem. Even the best tires don't stay inflated forever! The flap will have to be taped shut, I haven't found a better way to close it off . Clip all the tag ends before proceeding.

Now the other side gets attached. Unfortunately, hiding the tag ends of the zip ties is trickier for this side. I just left them on the outside. Below I've started by drilling two holes at the edges. I will be working clockwise, so securing the upper edge to the spoke is a good idea, but drilling the other hole was dumb! It worked out OK, but I could have been burned if the wheel's dish ended up being something different than I expected. Speaking of dish, you can see I don't have much on this side. Very little overlap.

Anyway, leave one edge free and work your way around the rim as before. Drilling the holes is trickier, because it's hard to see where the spokes are. Shine a light from behind; the spokes will make a shadow on the styrene. You will need to get your fingers behind the cover to maneuver the zip ties around the spokes and back out the other hole, so if you secure both edges or skip spokes figuring to go back later, you will find them to be inaccessible. Here, I'm working my way around the drive side. As before, clip all the ends when the cover is attached.

Here's the attached wheel disk. I will finish it by taping the overlapping edges with clear packaging tape. Not the ideal solution for opening the access flap, but easily replaced if it loses its stick.