Made A Cycle Truck Rack

I had a little bonus free time on Friday so I built the rack for the Cycle Truck. It is 18 by 20 inchesand made of 1/2 inchdiameter cromoly tubing with a 0.035″ wall thickness.

The rack itself is very basic and didn’t require much tricky work. It is a 2 dimensional rectangle and doesn’t have any stays or back stop (a back stop is not necessary since the head tube acts as one).

The connection between the rack and frame was the hardest part of the project. The frame has two support bars brazed to the cargo tube. These are made from 5/8″ square tubing and are mitered to fit around the cargo tube. I was careful to make sure that these were square to the cargo tube and head tube in the horizontal and vertical planes.

The support bars have 6mm holes at each end that the rack mounting bolts run through. The bolt, support bar, and rack look like this when connected together. The bolt goes into a threaded pillow block that I made on the lathe. The pillow blocks are brazed onto the rack. I thought about just brazing the rack directly to the frame, but wanted it to be removable so that I could easily replace it (if it gets damaged) or exchange it for a cargo box if I end up making one of those.

The hardest part was getting everything to line up well. There is no tolerance for error in the fitting of the pillow blocks to the support bars, the distance between bolt holes and the threaded part of the pillow block needs to be exact. What worked best (after some bumps along the way) was to braze the rear support bar to the frame, then thread bolts through the pillow blocks. The rear pillow blocks were tacked to the rack, then I placed the front support bar on the cargo tube and did the same thing there. Since all of the bolts were in place during the brazing everything was perfectly aligned.

I’ve done some load testing around the neighborhood with a 40lb load and the rack and bike handled well. I’ll be doing more rigourous testing and with higher loads later to see if I’ll need structure tying the rack to the frame. I expect that I’ll be adding two more stays that go from the rear support bar to the top of the head tube. This will both add some rigidity and will give me a nice place to mount water bottles. My goal is for the bike to ride nicely with loads in the 50-75lb range.

On Sunday I used it to carry this bulky but fairly light load. This is the kind of stuff that is really a bit too big for a normal porteur rack but small enough that I don’t like having to pull my trailer out for it. The Cycle Truck fits that niche between trailer and porteur nicely and I think I’ll be using it quite a bit.

I’m reorganizing the Cycle Truck photos into a new galleryto try and make it easier to understand the whole process without having a lot of extra photos. My only regret in this project is that I often got too involved and forgot to pick up the camera and take a helpful photo or two.

6 Comments

  1. Antoine says:

    The rack looks great and I like those Origin8 bars in silver.

  2. Francois says:

    Nice ! It’’s cool to see the finished product ! ;-)
    I had a look at your gallery, and I have a question regarding the frame alignment block:
    http://alexandchristine.smugmug.com/photos/310368491_ZYeLQ-S.jpg
    How do you center the dummy axle in the block ? Is there a screw to attach the axle in the block ?
    Thanks !
    Francois

  3. AlexWetmore says:

    The dummy axle has a groove in the center of it. There is a set screw in the V which centers the V with the axle.

  4. Apertome says:

    I said this on the Cycling Spokane blog already, but: damn, that bike is sweet!

  5. dan ewing says:

    It seems like that connection to the cargo tube with the square stock is pretty bomber, but I think I might have thrown in a stay or two from the outer rails down to the bottom of – or even running continuous under – the cargo tube to combat any rotational shifting forces with a large, hard to center load.

    Having said this , it’’s still awesome.

  6. AlexWetmore says:

    Dan — It’’s not quite done. There will be stays going from the rear cross stay to the head tube near the top tube.

    I”ve done some load testing with about 40# of weight, that worked pretty well. I”d still like to see how it does with 80# of weight. I think anything more than that would require having the front wheel pushed to the front of the cargo platform.