Make Your Own Cheap, Hard Shell Panniers – Part 2: Assembly

We went over the parts list in Part 1, now its time to get down to business and make some panniers.

This is part 2 in a two-part series.  If you haven't done so already, check out Part 1.

So Lets Build It Already!

Before you drill a single hole, or make a single cut, you need to take something into account that isn’t immediately obvious.

Measure For Heel Clearance

This is something you have probably taken for granted but will recognize instantly when your attention is called to it: Panniers have a diagonal cutout in their lower forward portion. The reason for this is so your heels clear the pannier when you are on the back side of your pedal stroke. A DIY pannier like a trash can does not have this cutout.

Fortunately, I knew to measure for this in advance. I was surprised when I saw how far back I had to go. Luckily the can slopes into a more narrow profile at the bottom, so half the work is already done for us.

How do you measure for heel clearance? The fact my bike shoes cleat into my pedals made that job easier: My foot position is always fixed in one spot. I just clicked my shoe into the cleat and rotated it.

I took the picture for Figure 1 below after installation. But I did the actual work by holding the can up against the rack with one hand, grabbing the shoe with the other and moving the can back until the shoe cleared.

Then I eyeballed the can relative to the frame to decide what spot was the final location: The front edge of the can is lined up right alongside the back edge of the bike frame.

NOTE: I eyeballed everything and measured almost nothing on this project. You will see some wavy lines as a result. It worked out, but you should be a little more careful than I was.

Figure 1: There is not a lot of clearance here, but you don’t need even this much. If it clears at all you will never know the panniers are back there while riding.

Measure the flat part of the top inside of the can

This will tell us how much flat bar to cut for the mounting plate. The hooks and bungie cord mounts bolt into this. If you don’t use a plate and just drill holes in the plastic can, thats not going to be anywhere near as strong, which is not something you want on a big bucket holding things for you on a bouncy road.

Figure 2: Here is what the plate will look like, after installation. The holes are off-center thanks to what we learned measuring for heel clearance.

You want the plate to extend only across the flat portion of the can’s side, stopping where the can starts to curve at either end. This gives you maximum contact without affecting the molding and shape of the can.

Cut the aluminum flat bar to match this measurement

For this can, it turned out a 10″ length was about right. You should confirm this measurement matches whatever can it is you are using. Even if you are using the same Rubbermaid wastebasket.

Decide where the hooks are going to go on the rack

I just manually placed them as far apart as I could, where each hook ends up jammed against a rack cross-support. That config for the hooks means once the pannier is assembled, it can not slide forward or backward on the rack.

Mark the mounting plate with the J-hooks’ bolt holes.

NOTE: This part is a LOT easier to do if you take the rack off the bike. Since I had an identical rack waiting to be installed on a new bike, I used that.

With the mounting plate attached to the outside of the can with blue painter’s tape at its proper fore/aft position, line the plate up to the hooks, which are still sitting in their mounting position on the rack. Mark the holes to drill in the plate thru the hook holes with a Sharpie. Remove the plate from the can.

We only need to go through this measurement process once, since the second pannier is a mirror image of the first one.

Drill the marked holes into the two mounting plates

Once those four marked holes are drilled on your first plate, line it up atop the the second, uncut one. Drill thru the existing holes, down into the second plate. Now we have two plates with matching holes. You just need to flip over the second one so it works on the other side.

Figure 3: The two plates are clamped together and the holes in the first are being drilled down thru into the second. The topmost hole hasn’t been drilled-through yet.

I used strong clamps to hold the two plates precisely, firmly together. As noted, I used M5 bolts throughout this project, so use an M5-sized drill bit.

Chamfer (partially countersink) all of the holes

As seen in Figure 2, I am going for a flat profile on the mounting plate, inside the can. To get that, I am using countersunk M5 socket head bolts, and larger M8 washers that are wider than the bolt hole, but narrower than the full width of the socket cap. The last ingredient in achieving this flush fit is to chamfer a bit of the bolt hole. That gives the beginnings of a full countersunk hole (since we are using a 1/8″ plate, we don’t have enough material to do a full countersink). Use an M6-sized bit to drill in the already-made M5 holes just a hair to create this effect. You can set the drill to reverse direction to just kind of grind in the chamfer (properly drilling it is very easy to overdo).

Drill the mounting plate holes through the can

Position the mounting plate on the outside of the can so it is lined up where it is supposed to be installed. When you do this, since the plate is on the outside of the can, but it will be installed on the inside, make sure you have the plate oriented correctly (i.e. not backwards or upside down).

Figure 4: I wrote myself a note to remind me which side should be installed up against the can on the right-side pannier. These bolts are just stuck thru already drilled holes to hold the plate in position while I drill the two outer bungee mount holes.

Again: Make sure you don’t reverse the position of the plate and get the holes backwards. I made this mistake on my first pannier, but fortunately that meant I could just flip it around use it on the other side… so long as I didn’t screw up on the second one and create two right-side panniers.

Do the bungee mount holes

I am describing this step out of order, as it should be done at the same time as the J-hook holes are drilled, above. I did things differently on my first installation, and this step actually came later and needed a complete disassembly to make it happen.

Figure 5: My original bungee installation re-used the lower hook hole for the bungee P-clamp. Just for starters the knots got in the way of the rack stays. After some use I came up with a better way to do this.

So the original installation used four holes in the mounting plate, and the final version uses six, with the two P-clamp holes being far outboard from the hooks, and more or less at the same vertical level as the lower J-hook holes.

This mounting position gives us perfect cable tension. It also leaves lots of mounting plate around the bolt hole so the washers on the outside are backed fully by the mounting plate on the inside.

Figure 6: Bungee v2.0 works MUCH better. Uniform length thanks to no knots or uneven cable cut. Thinner cord vs. the humongous leftovers I used from my parts pile. Enough tension to do the job without worrying me about long term damage to the flexible rubbery can.

Bolt everything together

OK so pretend all that stuff you see in Figures 2, 5 and 6 hasn’t happened yet. But its about to. We’ve drilled all our holes and now we bolt everything together.

Our J-hooks all use M5 x 16mm countersunk hex caps, with an M8 washer on the inside, bolt sticking out. Outside, we have the Jandd pannier hook, directly against the plastic. On top of that goes an M5 nylock nut (if you want to use a flat washer under the nylock, there are enough threads to spare to do that).

The two bungee mounts use identical bolts and washers, facing inside-out, with a steel M5 fender washer on the other side, up against the plastic. On top of the washer is the 1/2″ P-clamp, and on top of the P-clamp is another M5 nylock.

Assemble all of the bolts loosely

Since we are talking about nylocks, just screw them down by hand until the nylon lock ring stops you from using your fingers to further tighten it.

Tighten down the hooks first

Once all of the 6 bolts are hand snugged (they will actually be quite loose), tighten only the top two bolts of each hook. But not quite fully. The screw holes on the hooks are sized a bit large so you want to be able to re-align the hooks as you go along. Once you truly clamp to the plastic on the top two bolts, do the same for the bottom two, keeping the hooks properly parallel with your fingertips if they shift around.

Now do the bungee mounts

Pretty straightforward here. Tighten down while keeping the P clamps at a 45-degree angle as shown in Figure 6. When the bolts are fully tight they lock the P-clamp in position.

Figure 7: With everything bolted up, there are two ways to route the (red) bungee strap. I decided to use the right side routing as it lets the pannier sit directly against the rack stays… which will matter once you take in how the cinch straps work.

Add the cinch strap

Anyone who knows old school pannier bungee strap mounts knows I left out a step: There is no lower strap to capture the bungee and keep the pannier from flapping around, as the bike moves down the road.

Figure 8: These cinch straps are easy-on and easy-off, taking just a second or three to release or reattach. They are interwoven inside around the outside of the rack, inside the bungees and back outside the inside forward rack stay… so they can’t slip down.

This omission was intentional. Having a lot of cinch straps in a box in my shop, I opted to use them to lock the pannier down onto the rack. Removing the strap only takes a second, and the stability it provides works so well it not only never rattles, I could probably ride a singletrack trail without any worries about it moving.

Nest in the second can

We’re finally going to see why we’ve done that countersink stuff. Lets show it in a sequence of pictures; left-to-right:

So thats easy enough to understand. We kept the mounting plate flat so it would not interfere with the nesting of the cans. What is the point of that?

  • A double-thick pannier is much stronger, and loses all semblance of wobbliness. Stronger means stronger all around and includes the ability to take hits, lean the bike on things etc.
  • The interior is completely un-holey and waterproof.
  • The insert is easily removable. Once home from the shops, just pick up the inner can and walk it inside to unload.
  • When nesting the two cans, you can easily slip in a sheet that makes a lid for the pannier, with the 48″ flat bungee being an easy-apply band around it to secure the lid. The fact that the sheet is snuggled in between the nested cans makes it an attached, integral piece of the pannier, not a potential UFO if a strap comes loose.
  • That second can beefing up the operation makes the pannier system a substantial piece of kit… and costs a whole US$8 per side to add in.

Finish it off: Put on a lid

The very first idea I had for this job was the easiest to manage. It cost virtually nothing and was easy-peasy. I took a full size garbage bag and folded it into a 20″ x 17″ square.

Figure 9: Pannier Lid v1.0 – a simple folded garbage bag. It worked great!

The folded bag worked extremely well. It was easy to manipulate and rendered the panniers completely waterproof in rain and wind. The trouble was… it looked like I was using garbage bags for a lid. I wanted something that looked better. and so we have Pannier Lid v2.0:

I splurged on Amazon and spent $27 for some vinyl fake leather, ordinarily used for furniture re-upholstery. I used more material than I needed so I have the option of expanding the lid should I stuff things into the pannier that stick up.

You can see in one picture above how I have a second sheet with folded corners on a workbench behind the bike. That is the segment slipped in between the two cans as they are nested together.

Originally I had plans to do a proper measurement of just how much excess material I wanted to use, cut out in a pattern, where there was just the right amount and shape of fabric to stuff down in between the two cans for a fold-free fit all around. The right measurements on the rest would let me use nice hospital corners to fold up nice and neat on the outside, too.

I ended up just cutting a single sheet, 24″ wide in a straight cut off of the big fabric sheet I received. Then I cut that in half on the long side, leaving me with two sheets measuring 24″ wide by 27.5″ long. That 27.5″ side is the one that gets triangle-folded and tucked in between the two cans.

Because there is so much extra material for expansion, folding it up on the outside is a little less tidy. BUT in exchange for that the lid can expand considerably should I need it to.

And that, as they say, is that. Or is it?

Job done. I haven’t decided if I am going to use these for Bullitt II as originally intended, or leave them on this bike and buy four more cans and do another set for the other bike when the frame finally arrives later this month. Since its a white frame, I’d buy a white set of cans, but for almost everything else on the build sheet I have all the parts to do another set. Having a set to use as a reference, I can probably get the entire job job done in an afternoon.

Author: m@Robertson

I'm responsible for the day-to-day operations at my place of business: Leland-West Insurance Brokers, Inc. We do classic and exotic car insurance all across these United States. I'm also an avid auto enthusiast, a born again cyclist (i.e. an ebiker) and participate in medium and long range CMP and NRA sanctioned rifle competitions.

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