Saturday, April 16, 2011

Big Dummy-ifyed roof rack

D'oh! A super-sized Big Dummy versus normal sized rack tray.
In the two and a half years that I've had my Big Dummy, I've only hauled it somewhere in a vehicle a few times. When hauling was necessary, I was able to put it in the bed of my old pickup with little difficulty. Now that I no longer have a pickup, it was necessary to figure out how to load the Dummy onto a roof rack. The photo above illustrates the sad situation of when a longtail bike encounters a standard rack tray.

Commercially available long rack trays exist, which are made for long wheelbase recumbents, tandems and other freakishly long bikes. However, for me they have some serious drawbacks: A) They cost considerably more than standard rack trays. B) They are not typically stocked at bike shops. C) Most importantly, I don't already own one. However, I'm too stubborn to let these drawbacks hinder my quest for Big Dummy transport. I resolved to construct a long rack tray of my own that could be converted back to a standard bike tray easily, if I so desired.

I started out with a 14 year-old Thule rack tray featuring a fork mount, mostly because I already had it on hand. However, for my purposes, the parameters of the fork mount were key to determining whether or not the project could be realized. Some older fork mounts aren't compatible with disc brakes because there isn't sufficient clearance, but fortunately mine had clearance aplenty. If it hadn't been compatible, I would have been faced with spending money, which isn't exactly my style.
The disc caliper clears the fork mount. Expense averted.
So, once the fork mount was determined to be compatible with my Big Dummy, the project was a go. Finding an appropriate extension tube was the first step in the construction phase. I had a three foot length of a two-inch diameter fence post of the sort typically used for chain link fences. As a bonus, it had even been painted a similar shade of dull black as the tray. I marked a centerline along the post with a Sharpie. If you are reading this with the intent of building your own version, this step is important to ensure that the axis of each hole that is about to be drilled is parallel with the others. You'll see where I'm going with this shortly.
Marking a center line on the extension tube.
Next, I retrieved an eight inch section of a rack tray that I had previously trimmed from another rack tray used for carrying my daughter's bike on the Big Dummy. If you don't have an extra section of tray, you have a couple of options. One option is to cut a section off the end of your existing tray and use a longer extension tube to make up the difference, but this will make it so you can't go back to a standard length tray. Another option is to try to find an old tray at a yard sale or on Craigslist. Sometimes they are cheap or free if they are old or have broken pieces. As long as the tray is not damaged, the condition of the rest of the donor rack or tray assembly doesn't matter. 
Stub of a tray and the end of the extension tube.
The next step is to mate the section of tray to the extension tube. I drilled matched holes in the tube along the centerline, and in the center of the bottom of the tray using my drill press. If you're careful you should be able to do the same with a hand held drill.
Tube and tray getting the drill press treatment.
Matched holes, ready for bolts.
It was at this point that I had to use some hardware that I actually had to buy specifically for this project. I could have pieced together some mismatched sets of bolts, washers and nuts from what I already had, but I decided to go the extra mile to attain perfectly matched aesthetic beauty. I'm sure you'll agree it contributed to a spectacular outcome.
The only expenditure for this project was $8 and change for some 5/16 x 3" bolts, flat washers, lock washers and nuts.
I placed a nut on the bolt section inside the tube for the hole nearest the end, to avoid crushing the tube when the outer nut was tightened.
After the tray section was mounted to the extension tube to form an assembly, the next task was to attach the assembly to the tray. For this, I needed some mounting holes. I used an existing hole near the end of the tray for one of the mounting holes and then drilled another at the far end of the extension tube.
Two holes in the tray will correspond with two holes in the extension tube.
I flipped the tray over to make it easier to mark the locations to drill holes along the center line of the extension tube.
After drilling holes in the extension tube, the assembly is bolted in place.
I found it helpful to test the placement of parts by fitting the bike to the rack tray along the course of the project.
An important part of this procedure is to understand how everything fits together before drilling or cutting anything. I have a couple of other longtail bikes, so I made sure that there was some extra room along the short section of tray to adjust the wheel strap. In the event that I need more adjustment that is allowed, I can always drill more holes in the extension tube to extend or shorten the total length of the modified tray. In a matter of a couple of minutes, I can also remove the assembly and use the tray to mount standard sized bikes.
Top view of extension assembly.
Bottom view of extension assembly.
I reassembled the rack on the car with the fork mount toward the rear, otherwise the extended section would have interfered with the hatchback when open. I then mounted the Big Dummy on top. It worked like a charm. The design of the extension assembly causes the rear wheel to be mounted a couple of inches higher than in a standard rack. This higher location for the rear wheel improves the clearance for the cranks and chainrings over the lower section of the tray, and provides clearance for the bottom of the front fender, both plusses.
Now that's a Big Dumb roof rack. 
Note the room for medial adjustment of the wheel strap on the extended tray section. 
After all was done, I gave the Big Dummy a good cleaning to remove the magnesium chloride and road grime accumulated over the winter. It shined up well and looks pretty good for a workhorse.
Big Dummy clean and unloaded. Even a beast of burden appreciates a day off once in a while.

7 comments:

  1. I agree. It seems a little embarrassed without its cargo carrying components.

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  2. I felt like I should avert my eyes to avoid seeing it like that.

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  3. Thanks for the tip! I'm thinking of building up a Big Dummy myself. Which handlebars do you have on yours, and how do you like them?

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  4. Mark,

    Thanks for the kind words. You won't regret getting a Dummy. It's been a life changing bike for me.

    Those are 55cm chromo Nitto Albatross bars from Rivendell, which have been my favorite bars for several years. I have them on three different bikes right now. Albatross bars are very comfortable and enable a couple of different riding positions, not to mention a great view of the road. I've ridden them everywhere, from singletrack to a triathlon. Surly recently came out with the Open Bar, a similar style of handlebar also made of chromo by Nitto, which is about 66.6cm wide and a bit cheaper. I'm planning to get one to try out.

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  5. Hey, Nice! I was actually thinking of using a decapitated older tray to nestle in the new tray and do it that way, but this looks great. Once I figgered the crossrack technique, I was good for the 2 times in the last 4 years I have tried it.

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  6. I also initially planned to use another old tray to extend, but didn't have one to spare at the time. I don't carry my Dummy or Xtracycles very often, but this works well and feels just as solid as a factory setup. It's a great feeling to devise a good home-built option as opposed to buying yet another occasionally used thing.

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