Front Wheel Fairings for the DFXL

As part of the effort to help PeterB’s Battle Mountain run, we’ve been working one some front wheel fairings. These are added to the bottom of the factory pants to shield the exposed lower wheel. This has been a real challenge. The shape has to enclose the front wheels yet being wide enough to allow the wheels to travel through the steering arc. Also coming up with a shape that allows mounting to the curving bottom of the pants has been tricky. At this point, I’ve gone through three iterations of shapes. Each iteration involves building a plug, mold and part. So far, each shape has been symmetrical side to side so that I can use a single mold and trim the resulting parts to fit right or left. Before showing the evolution of shapes, here’s a photo of the latest iteration, painted and mounted on my DFXL.

The first shape that I came up with is a long teardrop shape with curved sides. The problem with this shape was that in order to open the tire slots wide enough to allow the maximum steering angle, the slots opened into the vertical part of the sides (due to the curve of the sides).

This lead to a second shape with vertical sides. This allowed plenty of room for cutting the tire slots in the bottom without the slots going up the sides. But the fairings looked massive when attached to the pants.

The third shape was based on the second but was shorter and with reduced volume.

So this is where we are right now. This 3rd iteration is smaller and there is enough room to cut the tire slots. It’s mounted with the use of magnets and tape as shown below.

However, I’m still not happy with the shape. The front seems too blunt and the tail should be elongated to make it more teardrop shaped. If I can muster the energy, I think that I’m going to modify the first shape to overcome its flaws. In the photo below, you can see the current shape in red and the first shape in white.

Oh and by the way… We have not tested the idea of adding fairings to the pants. For all we know, these things could add more drag than they’re worth. We’ll do some roll-down tests to make that determination.

“Screwless” Access Panel for the DFXL

There’s a little project for the DFXL that’s been on the back burner for a while. The front access panel on the DF is held in place by ten flat head m4 screws. I seldom need to remove that panel but when I do, it’s a bit of a nuisance. This can be particularly bothersome while out on a ride. In addition, I have to say that I find that the visible screw heads detract from the look of the DF. So this has lead to my “Screwless” access panel. There were 3 goals for the panel.

  • Be quicker to remove and re-install.
  • Give the DF a cleaner look.
  • Require no modifications to the DF body itself. The mounting system must be confined to only the panel.

Here’s the first iteration of the screwless panel. This was produced from my mold, followed by a little body work to remove the stock countersunk screw holes.

I’ve found that the addition of the NACA duct on my previous panels really made a difference when riding on warmer days. Here’s the screwless panel with a NACA duct added.

To mount the panel, I came up with a simple system of flexible tabs attached to the panel that would catch under the lip of the body. The tabs are attached to the panel using six carbon fiber slotted anchors that are epoxied to the panel.

Here’s the underside of the panel with the NACA duct and tabs installed. Different materials were used for the tabs in different locations to provide the right flexibility to allow easy installation but with a firm mount. The tabs slide into the carbon fiber slotted anchors made with a male/female squish mold. All of the tabs except the 2 rear tabs stay with the panel during installation. They’re just tucked in after the panel is in place. The 2 rear tabs are inserted after the panel is in place. It takes a few seconds to install or remove the panel. No modifications to the DF body are required.

This is the 3D printed squish mold used to produce the carbon fiber slotted anchors.

Full view of the DFXL with ducted, srcrewless access panel.

A Rear Wheel Fairing for the DFXL

I’m in the process of building some aerodynamic bits and pieces for the DF to be used by Peter Borenstadt at the Battle Mountain event coming up in September. I’ve made him a more aerodynamic hood and now I’m working on some wheel fairings to cover the exposed tires both front and rear. The front wheel fairings will be attached to the bottom of stock DF pants. The rear wheel fairing will attach to the underside of the DF. I decided to start with the rear wheel fairing.

This fairing needed to fit the contours of the underside of the DF. Rather than building the prototype of the fairing directly on the DF, I made a mold of the rear underside of the DF and made a copy from that mold to work on.

So the idea was to use the copy as the base for the plug. I would then form the fairing shape on the copy which would complete the plug. I would take a mold of the plug and I’d be ready to produce the actual part.

I designed the basic shape in Fusion 360. I translated that design to patterns to cut from a pink foam sheet using the software Slicer for Fusion 360. I then built a full scale version of that design from the foam cutouts, epoxy resin, body filler and a lot of sand paper. Next I fused the shape on to the plug base and added fillets where the vertical faces met the horizontal faces. I then made a mold of the completed plug which is the orange piece shown below.

Here as some photos of the resulting wheel fairing. The part was made with 2 layers of carbon fiber twill using the vacuum bagging technique. The final trimmed part ended up weighing 112 g.

PseudoMonster Sold

The current owner of the PseudoMonster, Stephen, has decided to part with this interesting trike. I’m handling the sale for Stephen.

Price: $1600 plus shipping to the continental U.S.A. ($150 maximum or less depending on destination)

Sold

Trice S / Vortex (AKA Pseudo Monster, AKA “Munster”)

Up for sale is a special Trice composed of selected Trice components to achieve a long, low, narrow, foldable fast trike. I am handling the sale for the owner, Stephen (BROL member “Munster”). This is the trike that Stephen has named the “Munster”. I originally built this trike and sold it to Stephen. My goal in choosing the components was to try to come up with a trike that was similar in configuration to the unobtainable Trice Monster. You can read about it here.

The heart of this trike is the Trice S cruciform. This is a hard to find part that offers the advantage of a narrow track and a stretched length compared to other Trice cruciforms. The extra length allows for more space to place the seat in a more laid back position. The rear frame member is from a 2010 Vortex. This foldable frame member will accommodate a 26″ or 700c rear wheel. The 349 front wheels and 559 rear wheel were chosen to give the trike a very low center of gravity.

I have just gone through the trike to freshen it up. I washed the seat and bags, replaced the chain, chain ring and rear shift cable. The trike is mechanically sound. It rides great. With the low center of gravity it flies around twisty turns. The frame shows its age with a fair number of scratches and scrapes. See photos below.

  • Crankset – 165mm Shimano triple (53-40-30)
  • Pedals – Crank Brothers
  • Chain – near new Wipperman Connex 9 speed
  • Front Derailleur – Shimano Triple
  • Shifters – Shimano 9 Speed Bar Ends
  • Tires – Near New Kojak 349s (front), Kojak 559 (rear)
  • Front wheels – 36 spoke 349 Velocity Aeroheat
  • Brakes – Sturmey Archer 70mm drums
  • Rear wheel – 32 spoke 559 Aeroheat with Velocity hub
  • Brake Levers – Tektro
  • Idlers – Terracycle dual idler
  • Rear Hub – Velocity with 11-32 Cassette
  • Rear Derailleur – 9 speed Shimano Deore XT long cage
  • Seat – ICE S hard shell
  • Includes modified Catrike 700 frame bags (see photos below)


Tail Extension for the DFXL

I’ve seen old photos on the internet of some custom modifications on Daniel Fenn’s DF. These mods were never made available for sale. One that looked interesting was the tail extension shown below.

A friend of mine, Doug from Riverside, recently was able to talk Daniel into selling him a couple of copies. Doug then surprised me by sending me one. I know that the extension probably wouldn’t make any speed difference for me at the speeds that I travel, but I wondered if it might improve stability in cross winds.

I’ve been working with Peter Borenstadt on a few aero pieces for his upcoming Battle Mountain run in his DF (see the “aero” hood in an earlier post). Peter had a home made tail extension so I asked him if he’d like to borrow the real thing. Of course he said yes. Before shipping it off to him, I decided to make a quick mold and copy just in case anything happened to the original. Making the mold wasn’t difficult. But it was tricky laying up the part because of its very thin trailing edge.

Here’s the original extension with temporary flanges and the resulting 2-piece mold.

To lay up the trailing edge of the part, I chopped up some carbon fiber material into short strands. I shaped a piece of wood with a skinny rounded tip that fit into the radius of the trailing edge. After applying the gel coat and letting it partially cure, I put the chopped carbon fiber along the trailing edge and up the walls a bit then tapped it into position with the stick. Then I just wet laid up 2 layers of cloth in the rest of the mold and overlapped the chop. The part turned out pretty nice with no voids but a bit heavier than the original. The original was just a single layer with no gel coat.

Here’s my copy of the tail extension, painted to match

I tried it out for the first time yesterday on a nice ride with my friend Gregory (who rode my WAW). I couldn’t feel any changes in stability nor speed. At least my red electrical tape mounting system worked as the tail didn’t fly off during the ride.

Fun With DF Hoods

A while back, I decided to make a mold of the factory DF race hood. This would give me the ability to make copies that could be modified for various experiments. In building that mold, I misjudged the draft of the hood. I mistakenly thought that I could extract my factory part from a 2 piece mold, split longitudinally. It turned out that the shapes around the visor locked my hood into the mold. I spent the weekend trying to extract my hood from the mold. I was almost ready to toss in the towel and start cutting the mold apart to rescue the hood. But with a bit more persistence I managed pull the hood from the mold without cutting anything. After almost losing my factory hood to the mold, I realized that this mold was not usable.

I set the mold aside and forgot about it for a few months. Then I began discussing with Peter Borenstadt (a regular competitor at Battle Mountain) how one could make a more aerodynamic hood for the DF. That got me thinking that I could modify my failed mold enough to yield a part that would be a good starting point for a buck for an “aero” hood.

So I cut the offending sections out of the mold and filled in the openings to build a plain looking hood (without the indentations for the visor). I then formed a piece of plastic (and later aluminum sheet) to change the angle of the visor area to be more laid back.

After a few rounds of bondo, sanding and primer, I ended up with this very blank buck. I was able to build a 2 piece mold from this buck, split longitudinally, since the shape was so simple. With the mold completed, I could go crazy and make all kinds of variations of the aero hood.

The buck for the “aero” hood

The first order of business was to make a test hood for Peter to play with. I thought that it would be nice to have a flush mounted visor. Here you can see how I came up with the inset surface to mount the visor.

To hold the hood in place, I copied the factory bungee tie down idea. I 3D printed a squish mold to form the carbon fiber strips to hold the bungees. I 3D printed the hooks that clip on to the cockpit rim.

Peter and I discussed the most efficient ways to extract air from the cockpit, considering that I had closed off all openings of the hood. Initially, I thought that some extractor ducts on the sides or top would be a good idea. Here are some photoshopped ideas.

Peter took a look at my ideas and explained that in his testing, the best extraction (with the least drag) occurred with a small opening (only a few inches wide) on the top as far back as possible.

Here’s what we came up with for the vent.

Here’s the first hood prior to being shipped to Peter. Since this is basically a throw away piece, I didn’t bother to match Peter’s DF’s yellow color. He may end up adding some cuts and holes that we will incorporate into future hoods.

Here’s the hood mounted on Peter’s DF. Peter did an excellent job of refining the fit.

Peter’s tests so far show the hood to offer only a modest improvement in speed. Here are Peter’s comments:

I did three runs with each top in fairly quick succession. The temperature and wind were very similar. The road is about a two mile shallow downhill going along the bottom of a canyon, with large trees on both sides. The canopy covers the top along most of the test section. All the runs were consistent and the racing top was consistently faster.
The vent works excellently. Starting at about 16-17 mph there was a nice stream of fresh air coming up from boom vent into the head area. Flowing by my face and around my head. I sat at the start for a few minutes to see if it fogs up easily and it did only slightly around the bottom visor edge. Fog instantly disappeared as soon as I started moving. It was cool and humid, so it was a good test. Interestingly, the ride seemed more stable at speeds over 40. It was just a small difference. Overall, I’m pretty happy with the results. When it is taped on, it should be even faster. I think I’ll be able to tape the visor as well, since the vent is working so well. I may reduce the front intake to a bare minimum, or close it off and make a small hole in the bottom center of the visor.
So here re the speeds:
STD roof, closed visor:
44.5, 44.2, 44.6
Racing roof:
45.1, 44.8, 45.2
Average for stock roof:
44.43
For racing roof:
45.03
Difference +0.6 mph for racing roof. About +1.35% speed increase.
At higher speeds it should be more effective. At 55 mph it should be closer to 1 mph more.
The noise level was very similar to the stock roof.

Moving on to some other experimental pieces… I saw photos online of a product that ICB was prototyping as a partial hood to provide shade. It was similar in concept to the Flevo Roof that many riders add to their velomobiles – only a bit more stylish. Anything to reduce my exposure to the sun sounded worthwhile. So looking at the photos, I copied ICB’s idea and built a “Sun Cap”. Here’s what I came up with.

While this did a decent job of providing some sun protection, I thought that it could have been more aerodynamic and could have provided more sun protection.

This lead to my next experiment. I thought that I could make a hood that had plenty of openings for air flow yet provide more shade and perhaps be a bit more aerodynamic than the Sun Cap. It wouldn’t be as enclosed as the factory hood. It would have more openings so that it could provide enough air for use on warmer days. So here’s my “Shade Hood”. I’ve ridden it on days where the temperature was in the mid 70s. It seems to move enough air to keep me comfortable. It definitely provides more shade than the the small Sun Cap. Notice that it doesn’t accommodate the factory flip up visor so I came up with a simple, magnet-mounted visor that I can pop on and off from within the cockpit while riding.

I’ve since popped out another blank hood. In the photo below you can see that I’ve outlined the cutouts of the Shade Hood for reference. I’m currently thinking of cutting it up to make something like one of these open top cockpit covers (without the NACA duct).

Update: I made cockpit cover similar to the white ones above, but I wasn’t happy with the clear visor. So I finished the sharp edges with a thin rubber strip. If you look closely, you can see that I had to add 2 more tie downs towards the back to get it to lie correctly against the body. (not ideal). To be honest, I’m not sure when I would choose to use this cockpit cover, but it was fun to make.

I think that I will make one last hood. I would like to have an aero hood similar to the one that I made for Peter with a flush mounted visor, no side openings and a small vent on the top. However, I think that I’ll go with a wider visor so that I can see my mirrors similar in shape to the Shade Hood’s visor above.