Bicycle Map Holder
UPDATE: We have a New and Improved Design HERE. This is the old and deprecated model.
Designing a Bicycle Map Carrier For Adventure Racing
I have been trying to get a decent map carrier for the bike for a while now. The ones that are commercially available are unfortunately equivalent to the cost of registering for an adventure race; so I started looking into building my own. Researching other adventure racers' designs, I was scared to death of the incarnations people had come up with. A vertical bolt extending skyward from the steering stem is a common design element among them and a sucking chest wound waiting to happen. Needless to say, there were good reasons for trying to roll my own.
My first attempt at the map case was a mimicry of their design--minus the impalement factor. Instead of using a vertical bolt, I used a PVC 90 degree Y, and a high-quality plexiglass board to hold the map. It was a modular design, and allowed for the easy replacement of broken parts (it was mostly plastic, so I factored in the inevitable endo). The fatal flaws--that the high quality plexiglass was not made of the same material as Gumbi and, secondly, it was discontinued by my local Home Depot--ended up pushing me over the edge and back to the drawing board. Though I suspected the board would most likely break and stocked up on sheets of the Lexan high quality plexiglass 11"x14" sheets beforehand, I depleted my supply after my third race. Not one race did I get through the entirety of it with my board still in one piece. Mark my failure: the pliability of even the highest quality plexiglass is no match for the general beating of adventure racing. And I imagine, given the fact that they sell replacement boards online for the commercial map carriers, the wooden boards meet a similar end after an adventure racing beating. * Granted, this is purely conjecture, and anybody who has used one of these feel free to weigh in on the discussion threads on their sturdiness.
Now, on to design part deux. What did I learn from the first try? Plastic, while light and rigid, inevitably breaks because it is not as pliable as is required. So the next design called for a material change--metal. I am not exactly an artisan, so I went to my closet for some wire hangers, figuring I could keep the final product light if I restricted the map carrier to a minimalistic frame. Additionally, the wire in the wire hangers would be pliable and in some cases premolded to how I needed it. Instead of a board, I had used a frame--saving weight on something that is not really needed. Replacing the board's ability to hold the map would be a Sealline map case with some caribiners on it to clip it to the frame. I had used three vertical pieces of hanger wire to attach the frame to the bike. I would use hose clamps to compress the vertical wires to the handle bars and steering stem and voila! a bicycle map carrier for adventure racing. Next thing to do was to test it out, and since the Odyssey One Day Adventure Race was eminent, I decided jumping right in at the risk of it breaking was better than having to stop every time I needed to check the map. But before the field test, it was time to wrap up those sharp dangling wires threatening to puncture my map. I used electric tape to do this job.
- 10-20 wire clothing hangers
- Needle nose pliars
- Vise grips
- Metal clippers
- 2 smaller hose clamps for handle bars
- 1 medium hose clamp for seering stem
- electric tape
Unfortunately, I quickly learned in the field that three vertical wires to support the case are too few. Further, while I twisted them together to form a strong central stem, it did nothing to prevent the carrier from swaying to and fro as I rode. The problem was that the weight of the map case coupled with the effect of the wind on it created a force that was far too strong for the central stem to remain static. The field test indicated that reenforcement of the vertical stem was required for the map carrier to be effective. There were two common positions in which the map carrier stayed:
- a forward-down position, where the front wire of the carrier frame was dragging on the wheel
- a back-down position where the map was flush against my chest as I rode
Back at the shop, I pulled a few more hangers out of the closet, and prepared to beef up the carrier a bit. The strong central stem succeeded at what it was built to do--to provide a static vertical support for the map case. However, it did not perform against forward, backward, and rotational forces. To best mitigate these, I would have to attach the frame to the far end of my handle bars. Because this would be a riding obstruction, I compromised, attaching the the frame to the middle of the handle bars. This would enable me to thread the wire through the other end of the hose clamps already in place, which on the positive side, meant a lighter design as no additional hose clamps were needed. Ultimately, I added four additional vertical wires, this time extending diagonally to the front corners and the sides. I did not connect it to the back corners, keeping the rear profile of the frame as minimalistic as possible to avoid contention with my knees during riding. At the same time, however, I wanted to position the map as close to me as possible (improving legibility while riding). Unless you get tricky, both are mutually exclusive. My trick here was to extend a couple of "legs" from the main, rectangular frame towards the rider to allow for the map to get clipped in when used. Because the "legs" are narrow, there is less chance of the legs hitting them during a race.
I slapped some more electric tape on the new additions, and prepared for field test numero deux. Jack was preparing for the Fool's Gold mountain bike race, so the team decided to pre-ride the course as a training ride to better familiarize Jack with it. I must say, the map carrier performed swimmingly. The map carrier remained in place, even during high speed sections where the map case was catching a lot of wind. The amount of wobble and twisting from which it previously suffered was greatly reduced, and this improved readability of the map. Best of all, there were two or three instances (including an endo) when the old plastic map carrier definately would have shattered; whereas its successor did not--beat but not broken. The beauty of it is that the field fix for the new map carrier is a simple matter of grabbing and bending the wire back into place. All this without the risk of a threaded stake penetrating my sternum! "But how much does it weigh?", you might ask. Though the new design is made of metal, dropping the board and using the wire for a minimal frame has reduced the overall weight of the map carrier to be less than that of the plastic design.
I am no metal worker; working with metal--even hanger wire--is difficult. Because it does not expand or shrink, lengths must be measured precisely. In that line, if the wire is bent slightly when measuring, it cannot be straightened later without affecting the system. This is the frustrating reason the map carrier looks a little wonkie, since I was learning as I went. I probably put in three to five hours building the map carrier. If I did it over again it might take half of that, as much of the time was spent finagling the frame and manipulating the wire, both of which became easier with time. One other thing I noticed was that there are different types of metal in the wire hangers--some hangers are thicker with a harder, less pliable alloy, while others have lighter but softer metal. There is probably a good balance to strike between the two, but I used all the wire hangers in my closet so I did not really have a choice. :)
So what was the outcome? A moderately lightweight metal frame-based bicycle map carrier for adventure racing that can take the beating it is given during a race with minimal field repair effort and maximum map readability.
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