Introduction: Aerodynamic Wheel Disks - for Your Bike
Looking for a little edge in the aero department? Aero wheels are the way. These wheel disks cost less than $2 each.
Step 1: Gather Materials
Here's what we used
A sheet of an unknown plastic. It was thin, very flexible and appears not to be very brittle. But more importantly, it was $1.75 for a 2' square sheet. I love surplus.
You will also need a cutting device - we used a jig saw with a fine metal blade.
A stiff backing - we used some scrap foam - this makes cutting easier
Step 2: Take Measurements - Mark Them
First, take some measurement. We need to know the radius of the wheel in question (in our case, 7 and 3/8 inches). We also need a hole to allow the quick release nut to go in place -- in case of emergency and we need to pop the wheel off quickly. That measurement was done with a caliper (3/4").
Marking your measurements is quite easy -- mark off the center of your circle by measuring your radius (plus an inch or so for safety) off of two sides of your plastic, then make a cross hair as shown.
Now, use a bit of string and your marker to generate a circle at the necessary radius. Just plant one end of the circle at the center of the cross hair and hold your marker at a radius' distance on the string. Then mark.
Step 3: Cut and Wedge
Now it's time to cut. Cut out your circle, then drill out your center hole (if applicable).
Now, we want to make a cone to follow the shape of the spokes as the move fro rim to hub. To do so, we need to cut out a pie shaped wedge.
First, cut out a straight radius. Now, place your disk on the wheel and squeeze the plastic around to form a cone. Mark where the plastic overlaps with a marker.
Next, cutout the marked radius. Check your cone shape against the wheel by taping the plastic together to keep the conical shape. If more needs to be trimmed - you can always go back and trim more. Just remember, the more you trim - the larger the cone.
Step 4: Fit and Duplicate
You'll likely find that your disk doesn't fit. OR, it rubs against the tire. Now is the time to break out the sander and start filing the edge down. It's helpful o mark where the disk contact tire, and then start sanding. This process will take some time - but your efforts will be worth it in the end.
To duplicate -- lay out the cut plastic flat on top of an uncut sheet of plastic. Trace the edge, cut, wedge and fit just like the first one.
Step 5: Finishing
You can paint - or in our case, we will be frosting our disks. Just sand one side until it's "frosted" - sanding by hand in one direction will yield nicer results.
To keep the cone shape -- lay out a strip of tape on the outside, then apply an epoxy adhesive to the inside of the cone shape to make a butt joint/bridge. Once cured, remove the tape and sand down the excess epoxy.
Attachment will be done with Velcro stuck to the wheel and disk.
OK, so technically this isn't complete. But, given my timing for the next couple weeks... It's now or never for publishing this thing ;)
Oh, and here's a picture of a meat person inside the fairing with the frame (slowly starting to cut and fit the frame inside).