It was getting warmer, and I was getting tired of packing my lunch, laptop and other junk on my back as I commuted to and from work. No one likes a sweaty back!
I looked at a some possible trunk bags to use, but they are all limited. The ones that would be big enough to hold my stuff were either too expensive or too small. Most require that straps or clips or something to be wrapped around the rack in some fashion. I saw some with a quick release feature, but these required a special rack and are beyond my budget.
So I designed a setup for the rack on my bike. I have the cheapest rack I could get. It's a classic steel thing with the spring wire mousetrap thing to hold stuff on.
My requirements? Cheap. quick release and fashionable. I know most folks are OK with a milk carton zip tied to the rack, but I gotta be cool!
It's not that complicated to make, but you should have some basic skills with woodworking. I made it in an afternoon.
What I used;
1/4 plywood, about 1 ft by 2 ft.
Some small scraps of other wood.
4 small (1/2" by 1') angle bracing. (Lowes or Home Depot)
Some screws and nuts. I used about 10 10-32 by 1" long screws and 6 wood screws.
A plastic snap clip,(scavenged from some dead luggage)
A bag. I found a nice tool bag from Harbor freight, costs about $8.
Woodworking tools. A jigsaw or scroll saw, a drill. A bench sander or sandpaper. Paint/varnish.
Step 1: Size and Cut the Base.
You'll have to size the base to fit your rack.
My rack and most racks I've seen have a bar in the front. First decide how wide you want your rack. 8 inches worked for me. Cut a rectangle to your width and about 3 inches longer than your rack. Draw a center line down the long length and make a 1 inch tab that fits into the front bar section of your rack. You should have some extra at the back.
Now cut the length so it just fits flush to the inside of the back end.
How you make the perpendicular rear part depends on your rack. My rack has a large reflector mount welded on the back that is perfect for my mount system. The idea is to have the front end of the base slip under the front bar and the back end held on by a single clip.
As seen in the photos, a smaller piece of wood sits perpendicular to the base and slots into the back part of the rack. This part extends below the top of the rack by and inch or so and thus prevents the base from shifting left and right and back. I made a single dovetail in the base and used some metal corner braces to make this part stronger.
Step 2: Make It Fit Snug Under the Front Bar.
To make the front fit snug, I needed a spacer. This is where your powered bench sander comes in handy. I had a piece of molding which has an 'L' shape that holds against the front bar. You'll have to use your imagination to design and make a similar part.
Make the spacer with a 1/4 to 1/2 inch tab to fit just under the bar. Use the sander to make this fit snugly but not too tight. Make sure there is little fore and aft play before you glue and bolt the piece on. Now sand all your corners so you don't get splinters!
Step 3: Attaching the Quick Release Buckle.
I have a plastic buckle, (I think 1 or 3/4 inch) which connects the rack to the reflector mount on the rack. I found a piece of webbing that matched the strap, about 12" long.
I drilled a 3/16" hole about 1/2" from the top of the back of the vertical back stay. Then I looped the strap over the top of the back stay tightly and used a sharp awl to poke through both sides of the strap. Now work a 3/4 inch long 3/16" screw through the strap, through the webbing and then through the webbing on the other side. Washers and a nut hold the strap secure. I used the same system to mount the other part of the buckle to the metal part on my bike rack.
Step 4: Attach the Bag
I painted the base a nice shade of black to match my bag. I also put a couple coats of varnish to protect the base from rain. Then I used 6 wood screws to attach 2 strips of plywood placed inside the bag to clamp it to base.
I've used this for a summer of commutes now and it works great! It slides on and off quickly and easily which is important when I fall asleep on the train and rush to make my stop! I'm not expecting it to do superX but it stays on during some curb hops and mild single track dirt trails. Make sure that the clips snaps positively before you ride or the bag can bounce off, but I haven't had this happen yet!. The $8 Harbor freight tool bag is starting to wear, but the base is still strong.
I ended up using some shoe goo on the bottom pointy parts to keep it from scratching tabletops.