DIY disc wheel cover

I got some requests to see how I made the disc wheel cover for my back wheel, so here you go.

Things you need to do it the way I did it (no cement):

-2 circles of high impact poly-styrene or ABS (not the exact same thing, but close) of .040" thickness

   [if you have the standard Shimano R500 wheels, 23" diameter works; if not, measure it first]

-electrical tape

-box cutter and cutting mat of some form

-pencil

-some string

-compass

-ruler (you'll want both the measuring ability and the straight edge)

-cassette removal tool

-chain whip OR dish rag+another person

-adjustable wrench

-your bike pump

-painters tape

-spray paint

-stensils (the internet works well for this)

Buying the plastic:

Do a google search for industrial plastics companies in your area and just start emailing/calling to ask if they sell ABS or HIPS in 040 thickness. Alot of companies don't sell orders that small or that thin of sheets, and some companies don't fabricate it for you (cut it into a cirlce). If you have it cut it yourself it wouldn't be the end of the world, just sounds really hard. After contacting probably six or seven companies in Houston, Caleb found one that sold them fabricated for $18 a circle. I had heard you can get them for about $12 a circle, or even cheaper if you just buy a big sheet and cut it yourself, but this sounded good enough. I ordered them on a Friday and picked them up the next Thursday.

To begin:

Remove your back wheel and take off the cassette. To do this, you need to put the cassette removal tool onto the bolt and unlock it by turning it in the direction of the freewheel. This is obviously impossible without some other tool because it will, well, freewheel. So using a chain whip, or another person holding a towel as I did, hold the cassette in place while turning the cassette removal tool. This is nearly impossible, took us over five minutes, and destroyed the rag we used. good luck!! watch a pro do it. Also, be VERY careful, your cassette will be in about 20 pieces at this point (washers and gears), so don't lose any of them.

Cut a hole in your plastic disc:

Find the center of the cirlce. To do this, I took a piece of string, held it at one point, and moved the other end along the edge of the circle, keeping it taut, and found where the furthest distance was from the first point. The string now goes through the center. I did this like four times from different starting points, marking it every time, to find where the lines overlapped as the exact center. From here, I've heard you can use 1.5" diameter circles on both drive and non-drive side, but I ripped my disc trying to take it off the drive side once the cassette was back on, so I made the hole 4" diameter; it's much more managable now. But anyway, use a compass, a 1.5" diameter cap of some sort, or some other way of tracing a circle onto the plastic and cut it out using a box cutter. It's gonna be hard to cut it as an exact circle, but don't worry, a mistake here will only ruin your wheel and make you DNF your next race (I've heard circle saws work well...for people who own such things). Also, make sure you're doing this over top of a legit cutting surface, box cutters will devastate most tables (not science lab tables though, I'm pretty sure those things are nuke resistant). Incase you're completely on the wrong track at this point, this is what it should look like:

Cut the disc so it can overlap:

The next thing you're gonna want to do is cut the disc along a radius from the middle hole to the edge so that the disc can overlap onto itself and fit the convex shape of the wheel. To do this, use your ruler to find a point where the distance equals (bigRadius-littleRadius), in the case of 23" and 1.5" diameters, that's 10.75". Draw this line, then cut over it. Box cutters seem to have a mind of their own sometimes, so I would recommend keeping the straight edge in place while you cut it just to keep it on track. Someone else should probably hold it, unless you have three arms. Place the newly cut disc onto your wheel and it should kinda overlap properly on its own. Like this:

Tape it in place with electrical tape. On the nondrive side you could cement it, but Nick told me when it starts to warp in the heat you're gonna have to re-overlap it, so you might as well just tape it and not even worry about the cement. Repeat this whole thing on the other disc. Like I said, for the drive side I used a 4" diameter hole in the middle to make it easier to slip the cover on and off without having to take off my cassette every time. It's kind of a pain in the ass.

Pump access:

The last thing you need to do before it's usable is cut a little piece off to let you be able to pump up your tires. In a race, you're gonna want to pump up your tires last minute but you're not gonna want to put these covers on after that. So you can cut a piece off like this:

You shouldn't have to cut on both sides, but I havent really tested it yet, so no promises. Make sure you give yourself enough room for the pump when its open. Also make sure that you don't buy tubes with stems twice the size of the ones that you cut to fit here. That would be dumb, don't do that. I've also heard of people just cutting enough room for a CO2 pump which is much smaller, but I don't plan on using CO2 at every race; that's wasteful and expensive. Up to you though. Also, tape the piece back on before riding. You only need access when you're pumping up your tires, not while you're riding.

Tape them to the wheel:

You're done, now just tape them to the wheel. For this, I used one continous strip of electrical tape around the edge. KEEP TAPE OFF THE BRAKE TRACK. Taping over the brake track would be dumb, don't do that. Put your cassette back on, put your wheel back on, and take it for a ride.

Decorating:

The next thing I did was decorate my covers. I decided I wanted a GT logo on the non-drive side and the google chrome logo on the drive side. To do this, you just stencil it, tape it, and spray paint it. Simple, but it WILL test the limits of your sanity. For the chrome logo, I wanted it to be 23" across, obviously, so I found a jpg on the internet, measured it on the screen, and resized it in paint by (coverDiameter/iconDiamter)x100%. For me it was like 623% or something. But now you have an exact size stensil. Just put some paper on your screen, trace over it LIGHTLY, cut it out, and apply it to the wheel. When tracing over the screen, it's best to use someone else's laptop so that if you press too hard and ruin the screen, it doesnt really affect your life.

Next, just cut around the lines with an exacto knife, box cutter, or a lightsaber. Trace your stensil onto the cover, 

tape it, and spray paint it.

Remember that the paint adds weight, so the thinner the coat the better. The can said it would be dry to the touch in 15 minutes, so I waited about 50 minutes before taking the tape off and taping the next part. This made painting the chrome logo take over four hours. Trust me, at this point, this is the last thing you want to be doing.

IMPORTANT: when using a dark color (green, blue, black, etc), cover the entire disc with tape except for the part you want painted. Paint mist in the air will settle on the disc, and it will give you a nice, dirty look. That happened to me, you can see where my tape lines stopped around the edges:

After painting both discs, I let them dry fully overnight before testing them out on my bike in the morning. I found that the part where it overlapped underneath the cassette needed to be trimmed. The double thickness part was rubbing slightly when I freewheeled (when you're just pedaling, the cover is moving at the same speed as the cassette, so any contact between them is inconsequential...I think); I didn't want to lose that energy via friction (or worse, have it apply enough force to unravel the entire thing), so I cut a tiny strip off the top. Also when riding this morning, the non-drive side cover untaped itself along the overlap and buldged outward. It stayed on because of the tape on the rim, but still. So just to let you know, this would be a great time to cement it in place, or use more than one strip of tape. I used two on the front and three on the back for my second short ride and it held up just fine for two miles. Lastly, the reflector on the spokes is really getting in the way of the cover fitting perfectly flush on the wheel; I removed the reflector and it fit much better.

Final pictures:

To make it really look sharp, I found a five pack of different colors of electrical tape. When taping it down, I put yellow on yellow, red on red, etc. And I think it looks bad ass. I'll race with it in an olympic on Monday and see how it works. If it holds up nicely I'll use it in my Ironman in three weeks. It felt fast on my test rides, but that may have just been because I was only riding 1 mile, not 100.