Cabela's

     Cabela's makes the funky plastic wheel shields pictured to the right.  As of 23/05/08, they are still only $25 for 4, that's right, FOUR!  They are made for 20" (406) wheels and the 2 sides for each wheel connect to each other through the spokes, using 4 bolts.  They work really well on 32 and 36 spoke wheels, but are a little tighter fit on 48 spoke wheels due to the 4 bolt mounting system.  They are a quick, simple and cheap way to get wheel discs if you are running all 20" wheels.  I used mine on the Python and the Bowden Baron.  These pass all 5 of my requirements, but they are only in the 20" size and look fairly hokey on a 451.

MK 3 Plastic

     Back in 2003 I found some .3mm plastic that is used to cover the fiberglass insulation that is wrapped around steam pipes.  I am sure there are other uses for it, but that's where this stuff came from.  Anyway, easy enough to work with using scissors and a thin punch/awl, and with a combination of duct tape, two way tape and white zip ties, both sides were fastened to the rear wheel.  A friend of mine helped me do it and with it being our first time, we were a little unsure how to effectively work with the stuff so there were a few bubbles and wrinkles in them that ended up finally getting caught in the rear derailleur and tearing the right side off.  In the bottom picture you can see the black marks from the chain and RD rubbing the plastic.  The most important thing we did with this stuff was to make sure the overlapping seam was facing the rear at the top of the wheel, and forward when it was at the bottom.  This way, it didn't scoop up wind and tear itself open.

     For tire inflation, I had to cut a couple zip ties on the off-power side and then zip it back up.  It was secure enough, just not tight enough to the spokes.  In the end, it was sort of a pain to do anything with the wheel so I took them off after getting the one side torn off, and left them off.  Later on I happened across the Cabela's discs mentioned above.

Raptor 74 Plastic

13 May 2008

     I decided to revisit the .3mm plastic and make some wheel discs for the Raptor 74 both for the small performance gain, and cosmetics.  So, first thing is to deal with the supplies.  Some masking tape to temporarily hold the disc to the spokes, some 2 way tape to close the seam later using the 1" x 12" plastic strip, an Exacto knife to cut the plastic, marker, leather punch (or scratch awl works too) and of course a 23" square piece of plastic(for the rear wheel) and my good sturdy pair of scissors.  After cutting a 1½" hole in the center and cutting a slit from the edge to the middle, I trimmed it into a circle to make it a little easier to work with.

     I started by ripping off a bunch of small pieces of masking tape and sticking them to my arm to keep them handy.  Also handy for crude hair removal.  Anywho, I started on the drive side with the cassette removed because I want the disc super tight and smooth so it doesn't get snagged by the chain, RD or sprockets and ripped off like the MK3's.  I took the disc, lined up one edge of the slice in between two spokes, and taped the backside of it to a spoke.  Slowly working my way around, making sure the disc stayed fairly well centered on the hub, and making sure the disc stayed flat and mainly wrinkle free, I worked my way around the wheel and taped every other spoke on the drive side.  The end result is in the bottom picture.

     Now, you can see the slit I cut in the disc.  Due to the wheel's dish, the slit edges overlap a fair bit at the rim, and taper down to nearly no overlap when you get to the hub.  The plan is, I'll be taking a narrow piece of strong 2-way tape and sticking it to the underside of one slit edge, and pressing it to the top of the other slit edge.  The tape is about 1" wide and is long enough to run from the rim, right to the hub for maximum contact and holding power.  I won't be doing that though, until it is trimmed to the correct side, the zip tie holes are punched and I wipe the dust and dirt off the plastic so it is nice and clean and the tape has the best chance of sticking.  Also, of major importance, is to get the overlap in the right direction because if you don't, the wind will rip it off!  So, when the slit is at the bottom of the wheel, make sure the rear side of the slit is overlapping the front side of the slit.  This puts the raw edge of the slit facing forward at the bottom and means that as the wheel is rotating, the edge of the slit is facing backwards at the top when the slit is going AGAINST the wind, and facing forward at the bottom when the slit is going WITH the wind.

     I don't know what happened to the other pictures, but this is the end result.  After getting both discs made, this is how I mounted them.

1. I mounted the drive side disc using the same process as before using masking tape and making sure the disc was tight to the spokes and smooth.
2. I used the narrow strip of 2 way tape and stuck the two edges of the slit together to help keep the dished shape more rigid.  Then, I carefully removed one piece of masking tape at a time and replaced them with an equal length of strong duct tape in the same place the masking tape was.  The duct tape helps further with keeping the disc tight to the spokes.
3. After the tape went on, then I carefully threaded the zip ties through the holes and around the nipples, made sure the lock was going to be on the inside of the disc, nice and tight, and then cut off the extra tails.
4. For the non-drive side, I used one smaller piece of duct tape to help hole the disc on one spoke, and then slowly started installing the zip ties.  Putting in the ties on this side took a little longer, but by going slow, the ties could also gave the lock on the inside, and I pulled the tail of the zip tie out between the disc and the rim and initially left the ties a little loose.
5. When I worked my way around to the slit, I put the last zip tie in and left it good and loose while I applied another narrow piece of 2 way tape.  After the tape was applied and the slit was now flat, smooth and well joined, I went around and tightened up all the zip ties, and while holding the extra tail out, I cut them off too.  The wheel discs were done.

     Now what about tire inflation?  Well, I took the disc for the non-drive side, and before I put it on the wheel for the final time, I cut a small arch where the valve stem was and I cut a matching piece of 2" masking tape to cover it.  You can get low profile, right angle pump heads specifically for inflating disc wheels so the opening doesn't have to be too big.  Most other guys just cover the valve stem opening with something simple like a piece of tape too.  For more serious wheel and spoke maintenance, I'll need to cut the zip ties.  The front discs were made exactly the same way, only smaller in diameter.  I put the valve opening on the left side disc, away from the chain, and I treated the chain side disc the same way I treated the drive side disc at the back.  After the discs were mounted, then I took the wheels and spray painted the discs.

Raptor 74 Spandex

23 May 2008

     So, after a week of riding with the new discs, it definitely adds a pucker factor out on the open roads on a windy day when the wind is wanting to do craziness with the front wheel disc and your steering.  It also definitely makes downhills more work, and less fun than before.  This wind-steer effect might be able to be reduced with experimentation on weight distribution, changing the steering geometry, or both, but I'm not chopping the bike up trying to hunt stuff like that down.  Also, more time with the wheel discs would likely help me develop better control skills, but I have another idea - spandex.

     The idea is that some thicker spandex MIGHT still be tight enough weave to help the wind transition over the tire, the rim, parallel to the face of the spandex, and then over and off the back edge of the wheel.  At the same time, strong side winds might penetrate the weave a little and reduce the wind-steering force on the front wheel.  I also have an idea of a much simpler, tool-free way to install and remove the discs in seconds for things like tire inflation, wheel maintenance or just if the need should arise that the discs need to come off.

5 Jun 08

     So the idea is that I use some thick spandex, some stiff, small diameter steel rod and some of those small plastic clips you use to nail phone cord to trim.  Make a loop out of the steel, cover it with a sewn on spandex cover, and hold it to the spokes with the clips.  We'll see how it goes. The little plastic clips come with a nail so I pull those out, drill out the holes a little bigger so they slide down over the nipples, and then slit the side so I can pop them on the spokes.

10 June 08

     After a couple of days of commuting, the covers seem to work well.  Installation and removal is a piece of cake and requires no tools.  I question the strength of the plastic clips though.  A couple of them look like they are going to pull off the spoke nipples.  I think I need to come up with a better solution, just in case.

12 June 08

     So, on the way in to work this morning, flying along pretty well, a bit of a cross wind gust popped the one cover off.  Luckily it just wound sort of crazy around the axle and there's not enough hard stuff in it to lock the front wheel and cause a wipeout.  So I took the covers off (because it had jettisoned 3 little clips when it let go) and the rest of the commute in was spent trying to come up with a fix.

     And . . . the fix is to make some small metal hooks out of thin steel filler rod, bend them into the shape pictured to the right, and put those over the spokes instead.  They're pretty strong and the hoops are pretty tight, so I should only need about 4 per side.  Seems to work fine and again, no tools required to install or remove them.

13 June 08

     Interesting development today.  At about 70 kph I look down and I see the spandex discs bulging.  Each side was ballooned out almost 2" per side right behind the rim at the front of the wheel.  I guess the discs are air tight enough that the high speed air rushing over the surface of them caused a low pressure area on their surface right behind the tire/rim combo, and created enough "lift" to balloon them out.  Cool, but it sort of freaked me out for a second.  I'm not sure if that's a good thing or a bad thing, but there is definitely less wind steer on the spandex than there was on the solid plastic discs I first made.  Again, I don't know if this air bleed is a good thing or a bad thing.  I imagine a little air pushing into the spoke area is not as efficient as keeping it out, but then the air bleed makes the front end more controllable.  More riding/testing is required but right now, aside from maybe the bling factor, I'm not sure how much of an advantage they are giving.  At the very least, I'm pumping less air with the spokes.

21 June 08

     There I was at the Waterford races, losing most convincingly kicking serious butt! ;)  Along comes a crosswind, and rips off the left side cover and twists it into a real mess, in the middle of a race.  I stopped, ripped it right off and carried on.  Why, oh why didn't I put EIGHT clips per side on it instead of only 4???  I went back to retrieve it after the race to salvage the hoop, but the wind had blown it away by then.

     So, I'm thinking the whole spandex disc thing was a success.  It was very easy to make.  It didn't cause a wipeout if it let go and I think they looked good too.  I don't know how much aero effect they provided due to their porosity though.  I also don't know how much of a speed benefit they added.  The solid rear disc worked like a charm though. So no complaints there. I have to think about whether I make a new one like the other side, or whether there are other options.

     A couple thoughts . . .

1. What I would really like to do is use some thin bamboo/plastic rods with a draw string to keep the spandex on it, but I can't find any thin rod anywhere.
2. For a disc brake setup, why not just use the same draw cord as above, but put it inside the rim, and then mount the tire over top?  I could make the other side more accessible for spoke and pressure maintenance. The ideal thing would be to go with high pressure airless tires and be doe with it, but no luck finding those.

     Anyway, some things to ponder.  One thing I do know, no matter whether it has 2 wheels or 3, BOTH sides of the wheels on anything I race will have wheel discs from here on out.

Black Max Plastic

6 Apr 09

     Still being of the mindset that covered spokes are a good thing, once again into the breach, and all that rot.  The Black Max tilter is aimed primarily at performance so it's a sort of no-brainer to put discs on the wheels, plus ,the fact that all three wheels have disc brakes means there is a lot more latitude in disc design and installation than with a rim brake wheel.  That being said, I used the same technique as on the Raptor 74, and installed plastic discs on all three wheels.  The end result is to the right.

     With the disc brakes, I did the caliper side first because it's more critical to get that disc tight and close to the spokes.  Clearance between the spokes and the brake pad adjustment knob can be usually is tight.  The outside discs on the rear wheels went on last.  The front wheel was more problematic.  The drive side has the cassette and derailleur, while the left side has the disc brake caliper.  I opted to do the cassette side first and take my chances on the left side.  So far so good, and the discs are tight and not rubbing

29 Apr 09

     Had great fun at the HPRA Indy Fest and things went well, but the left front disc started rubbing a lot and I won't run just one side, so Itook them both off.  Back to the drawing board for the frotn wheel but the rears are fine.

Black Max Coroplast

16 Dec 09

     So, the plastic discs worked fine, sort of, until the wind got at them while going to a HPRA race in North Manchester IN, and that was all she wrote for those.  No big deal, and the trike went discless for a while (no more races this year) until I got a hold of some 4mm Coroplast.  I'd tried the thicker stuff before, but again, clearances are tight so I wanted to go with the thin stuff if possible.  I used basically the same techniques for the Coroplast as I did for the plastic.  With the Coroplast though, I used some nice, ultra-stick duct tape on both sides, and made sure the tape on the outside wrapped well around the edges and up the inside about 2 inches.  I did the inside discs first because it was more important to get the caliper side tight to the spokes, and then I did the outside and painted them flat black.

     The end result was secure and quite acceptable.  I think there is slight rubbing on the one inside disc because the Coroplast shifted slightly, but I don't notice it when I'm riding.  They worked quite nicely at the Florida HPRA races, and I don't think they look too bad in the picture to the right.  I still need to come up with something for the front wheel though and am leaning towards Dacron.  We'll see.

Black Max Dacron

1 Apr 10

     I saw another HPRA racer using Dacron on his wheels as discs, and it looked clean, effective and robust.  Dennis Grelk is fast on his lowracer, and he uses the Dacron discs on his 451 wheels, which are all Sturmey Archer drum hubs, so he has teh rim brake area to work with.  I was a little leery to try it because I figured it took more finesse than I could muster.  I asked him for any advice or tips on how to do it, and his method, and explanation were pretty simple.

     I bought some 1.8 oz Dacron from Aircraft Spruce and just got enough, this time, to do one wheel, just in case for some reason it's not my "thing".  Anyway, the process I was advised to follow was this:

1. Deflate tire
2. Cut a hole for the hub and measure out enough extra diameter to be able to tuck about an inch around the edge of the rim.
3. Take a brush and paint some contact cement on the edge of the rim (I used some 3M high strength stuff I had).
4. Put the Dacron on the wheel and pull it reasonably tight while pressing it down on the edge of the rim.  If you are too slwo and the contact cement starts to dry already, you can always touch up the spots later as the cement will wick through the Dacron.
5. wrap the Dacron around teh edge of the rim, tuck it in between the rim and tire, and inflate the tire to help hold the Dacron in place.
6. Use an iron at medium heat (my iron was set in the "Nylon" heat range) to work around the surface and shrink it down.  It's good to wait about 15 mins to make sure the contact cement is well dried before shrinking.

     To the right is the disc rotor side of the wheel.  The Dacron has been glued and tucked, the tire is inflated and the glue is pretty much dry, so I shrunk it down with the iron.  I made sure the wheel's spokes were tight, the wheel was true and the speedo magnet was also tight.  I touched up the glue in a few spots by using an Exacto knife to gently lift the worst spots and apply a little fresh glue with a small tongue depressor.