Friday, September 28

supereasy DIY rear rack

NOTE: Before building this rack, scroll down and read the postscript.

So you want a rear rack for your bike - or any kind of rack for that matter - but you don't have the tools to weld or braze or whatever. Well never fear, comrades, J-B Weld is your friend!

Before we get into the actual rack stuff, let me just introduce you to J-B Weld properly, in the words of their own website: "My pickup threw a rod and tore a hole in the block. I plugged the hole with large washers bolted together and sealed it with J-B WELD. That was over 50,000 miles ago; still with no loss of oil. Thanks for a remarkable product!" There are hundreds of awesome testimonials like that, but not all of them are as sublimely redneck!

So here is what we need to build a rack, and it is all available at your local Autozone or other auto parts store. You want 1 package of J-B Weld, and 2 lengths of 3/8" rigid steel high pressure line. This is the stuff you can use for brakes, power steering, etc. It is soft steel so it is bendable. You might also want to pick up a tubing bender for this, and a tubing cutter if you don't have one. You will also need a round "rat tail" file, and auto parts stores usually have pretty good deals on tools, so why not get one there too.

The first thing you want to do is cut the two main pieces of the rack that will go from the seatstay rack eyelets to the dropout eyelets. Crimp one end of each. I used a bench vise, but a hammer would work. So would vise grips if you are truly desperate or one of those sickos that enjoy using vise grips.

Once you have a nice crimped section, drill a hole in it to accept a standard M5 allen head bolt. You don't want a lot of play here, so try to use a bit that is just barely bigger than the bolt. I think I used whatever size is just smaller than 1/4".

Now bolt that sumbitch to the seatstay eyelet. You will have a long straight piece of tubing to work with at this point. Begin bending it to the shape you want the rack to be. Note: A milk crate is about 13" square. Use a tubing bender or some sort of v shaped round thing, like a swamp cooler belt pulley, to keep the tubing from kinking. You will see an example of kinking later in this article. Try not to do that if you can.

My goal was to get the rack level, and leave about as much clearance between the rack and the tire as there is between the brake bridge and the tire. Since you left the tubing long, you can get it where you want it than mark it for cutting, crimping, and drilling for the dropout eyelet.

Once you have the two main pieces done, you can make the little struts that join them and for the platform for the rack. Just cut 3 (or 2 or 4 or whatever) pieces the same length, and use your round file to "fishmouth" them so that they form a nice fit with the main rails. Remember that your file will stay sharp much longer if you only drag it across the metal in the cutting direction, never backwards.

It is now time to mix up a batch of J-B Weld! Awright! Just mix equal parts of the steel and the hardener. I like to use a nail or something else disposable so you don't have to clean it.

Spread J-B Weld on the end of the tubing, put the pieces where you want them, and use bungee cords to hold it all in place.

Next go back and make "fillets" with more J-B Weld. This is easier that it first appears because J-B Weld has a cool surface tension property that makes it self-smoothing. Just get it to stick where you want it, and it will slowly pull itself to a smooth finish.

Let it harden overnight, remove the bungee cords and you have yourself a rack. Paint it so it won't rust, and you are ready to roll.

POSTSCRIPT: This rack broke almost immediately. It turns out J-B weld is not as cool as I thought it was :(


Blogger Mark Manson said...

Sorry it failed but, man, that made for a funny story.

Sunday, 30 September, 2007  
Anonymous dave said...

Instead of the JB weld, what about crimping the ends of the cross pieces flat and then either bending them around the rails, or doubling two cross pieces up and sandwich-bolting them top and bottom to the rails?

Not as sexy, but no extra tools needed.

I bet you could think of a better idea along these lines.

Sunday, 30 September, 2007  
Blogger Tarik Saleh said...

I was about to be really impressed if that worked. You clearly should have wire tied it as the JB weld was setting up and then you would have been golden!

Sunday, 30 September, 2007  
Blogger jsn said...

Yeah, this was a pretty dissapointing project. I expected the rack to last more than about 10 feet with a basket zip-tied to it and full of clothes for the thrift store. I mean if it can't handle clothes, it will never handle a 30-pack!

I ground off the JB Weld and tried it again with PC-7 epoxy. My hopes are not high, but maybe I'll get lucky.

Monday, 01 October, 2007  
Blogger jsn said...

sweetnourishingbikes co-conspirator Brian and I talked about alternate ways to attack the horizontals to the rack, including bending them as you describe, Dave. We also thought of maybe using some kind fo pin system, and perhaps some sort of crimp-and-slot type thing. At this point it would have been much easier just to braze it up. But I would like to figure out a no-heat rack. And I have some ideas for DIy fenders that I will post when I get around to building them.

Monday, 01 October, 2007  
Blogger Marrock said...

For the horizontal struts, why not just drill holes through the side rails, then run threaded rod the same diameter as the inside of the tubing through the struts and stick acorn nuts on the ends.

Tuesday, 02 October, 2007  
Anonymous Anonymous said...

Sorry the rack failed. Until I got to the postscript, I was pretty amazed.

I don't think JB Weld is the problem, I've had success with it on projects before, although never as 'structural' as this.

I was initially amazed that the high pressure line would be sturdy enough to work. I think you should retry it with solid rod of some sort. In addition to being sturdier than brake tubing, it would give a lot more surface area for the 'weld'.

Of course, you're going to have problems 'crimping' the solid rod for the connections, so maybe make 'gussets' out of the brake line, JB Welded to the solid rod for the connections?

Tuesday, 02 October, 2007  
Anonymous dodge auto parts said...

I like it. I love seeing personalised bikes; you see quite a few around Oxford

Thursday, 21 August, 2008  
Anonymous Anonymous said...

These auto parts are amazing and I must prefer Auto Parts Warehouse Code for buying discount accessories of it.

Thursday, 01 October, 2009  
Blogger Carl said...

to resurrect an old comment thread... i just made one using your design but instead used EMT conduit from the hardware store and for the struts crimp and bolt. worked amazingly and cost 5 bucks.

Tuesday, 23 August, 2011  

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