# Aerodynamic Wheel Disks - for Your Bike

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## 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

A Sharpie

Measuring Tape

String

Sand Paper

Caliper

## 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).

## Recommendations

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## Questions

I guess zip ties could also be used to connect the two sides through the spokes, if velcro isn't on the budget (though it's cheap too). Nice idea, might look into it

Any ideas of how to secure it to the rim?

2 replies

'ble says "Attachment will be done with Velcro stuck to the wheel and disk."

thanks!

Your fairing looks amazing and reminds me of the light aircraft I built -absolutely the best thing I have ever built or will build. Some details would be much appreciated. Thanks, Chris.

I Ride a Hi Performance Hybrid my wheels obviously are 700 or 27 inches im thinking of installing paneling but only for half of the lenght of my spokes using coroplast material the look is sand blasted half way will let the wind go trough and give me a fast edge at the same time, thanks for the instructions about

measurment cutting and sanding i have 24 spoke criss cross patern wheels im woudering how to fix or secure the panels to the spokes and it got to have aestetics no zip ties so anny ideas or suggestions ? Im thinking of using stacks of coroplast square stuck with epoxy and to unify both sides using velcro so yeah anny ideas?
Thanks
Simon.

I've been looking into doing this for a while, but I have a pet girlfriend who doesn't like power tools in the apt (\$\$\$ and noise, what a wacko!). If possible, I'd like to see a photo or a description of attaching the wheel to the rim. The velcro sounds good, non permanent and simple. Any problems with this so far? One idea I had was to include 'tabs' around the edge of the discs, which extend over the edge of the rim, fold at the rim, and are clamped down by the inflated tires. The plastic would have to be pretty thin though, and you'd want the visible edge of the disks to come all the way up to the tire.

hahah meat person! i'm curious as to what your other drivers are made of.

hehe, in our computer model, we have lego guy (just because his head is a cylinder and his body is boxy).... All of the riders are 100% meat people - that tend to not look like our lego man model :)

Sweet. When I have a spare road bike I will try this. But I can't use my main bike because I ride where there are strong crosswinds and I already nearly get blown off the bike!

2 replies

Last picture in the post shows him, in his fully faired bike... upright riders probably shouldn't be using this type of device... If you're lucky enough to know someone in the music industry (drummer, drum repair shop, etc.) Loose drum heads with "hub holes" also work if your wheels are the same size as the heads. Added bonus that they're tough as nails, stretchable(to a degree), and old beat-up heads can be had for almost-to-completely free. Just have to make sure to get a Head rim size to match your wheel rim size :-)

Uprights can benefit from having full or partial aero wheels ;) Especially on terrain without high grade slopes (where the weight penalty overcomes to the aero advantage). I like the drum head idea :)

Fully faired rear wheels can make some improvment on an upright. But don't used faired front wheels! Very dangerous. Once the wheel starts to turn the airstream will force it to turn more.