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I have been unable to find a pannier set that works exactly as I would like for the under-seat rack on my RANS Rocket. I like the panniers made by Arkel of all the panniers I have looked at and used.

I decided to make my own set tailored (quite literally) exactly to my needs and I borrowed quite a bit from Arkel’s design work. Below is a description of the process for those who would like to do the same.

I tried to think of a reason for why I should taper the bottom of the bag. I couldn’t come up with one. The rear bag is usually tapered to eliminate heel strike. With a pannier hanging under my seat, I don’t have that problem. My current panniers for the under-seat rack are Arkel GT-30’s. These are normally used as front panniers and are tall and skinny. The biggest problem with using them on the under-seat rack is the occasional dragging while turning at faster speeds and more lean. I also wanted quite a bit more storage under the seat, to get as much weight low and forward as possible. I mocked up a pannier using a cloroplast back plate and paper, to check the size and clearance when the bike was leaned over to 45 degrees. I should never get that far over while turning, but it gives me a decent safety factor. I decided on a size of 18″ long, 12.25″ tall, and ~6″ deep. The zipper sections have the most seams and allowances, so I wasn’t sure what the exact final depth would be. I planned using standard 1/2″ allowance seams for everything, except for the specialized seams on the zipper.

I purchased most of my raw materials from The Rain Shed, which is a good source for outdoor patterns and fabrics. I would recommend anyone starting out making outdoor equipment to pick up Sew and Repair Your Outdoor Gear. I ordered it along with my fabric from the Rain Shed and it was easily worth the $17. It is available little cheaper from Amazon (link on that page).

I am using a 1000 Denier Cordura for the main fabric of the pannier. The Cordura I used is the gray fabric in the pictures. I need 4 pieces of fabric for the main body of the pannier: The front of the pannier (which I define as the side facing away from the bike), the back and bottom, and the two pieces that make up the sides and top. Both of the side and top pieces run parallel with each other, with a zipper in between them. All this should make more sense as you start to see pictures.

I started out with the side/top pieces, because they would take up most of the width of the fabric. I wanted the strength of the fabric (the warp) to be along the short dimension of the pieces, so they have to be cut with the long axis parallel to the weft. (Warp are the threads running the length of the fabric, Weft are those running “back and forth”.) The dimensions for my two side pieces are 7.5″ x 44″ and 1.5″ x 44″.

I should point out that the most important things to do with synthetics after cutting is heat sealing. You don’t want you bags to unravel during use and scatter all of my contents across the road! For most thin synthetics, you can use a good hot knife for both cutting and sealing. While I’ve used a hot knife for thin nylon, I would guess that it would be hard to cut fabric this thick without leaving a large hard edge of melted nylon. I used a cheap soldering iron for sealing the edges of the Cordura, after cutting out with very sharp sewing scissors. This didn’t leave hard edges, but secured the fibers well.

I’m using a YYK size 10 coil zipper for the pannier. The size 10 is about the largest you can get and should wear very well. The coil zipper will run around the curves of the pannier much better than a toothed zipper and the strengths are about equal.

I started with the small side piece. The first seam is stitched with the wrong side of the zipper and fabric out. I used a zipper foot to stitch along the zipper, leaving enough room for the large sliders. After the first seam was finished, I pulled the fabric back, so the right side was facing up and stitched the second seam using the regular foot against the zipper (the spacing worked out just right).

In both of the pictures, you can see the two seams indicated with red lines. The first image is from the right side of the zipper and the second from the wrong side. Just above the red lines in the wrong side picture, you can see a little of the folded over fabric sticking out. I tried to line up the edges of the zipper and fabric for the first seam, but I slipped a little.

For all the seams in the pannier I used a nylon thread. From what I have read, cotton can rot and the nylon fibers of the Cordura will cut polyester. I used heavy duty nylon thread through out the pannier construction.

The first step for the larger side piece is sewing on the reflector strips, made from 3M reflective fabric tape. I located them so they would be halfway up the side. Also, don’t get distracted and sew the reflector on the wrong side. I’m seam ripping out a reflector after doing exactly that.

I was concerned about the exposed edge of the reflective tape at first. After sewing a piece to a scrap of fabric and scratching over it for quite a while with my fingernails, I was unable to get the tape to unravel any significant amount. I think it should hold up fine without rolling over the top edges. Any time the ends of the tape are exposed, however, they need to be folded under before being sewn. For these side pieces, both edges will be covered by edging on one side and a seam to the back on the other.

Here are pictures of the reflective tape. I got a laugh out of the shot with the flash was on. The reflective tape seems to work!

To the left you can see the two side pieces. The smaller piece is finished, except for being joined to the front panel. While it looks like it curves, this is only because of the zipper seam pulled that edge of the zipper together, making it shorter. This will go away after you sew along the other side of the zipper.

The larger piece has both piece of reflector tape sewn in place (on the correct side!). One edge of the larger side piece will be exposed, because it is acts as a flap for the zipper. I used 3/4″ cross-grain nylon ribbon to treat the edge. This looks much nicer than a raw edge and should also keep it from unraveling.

I found it easier to sew this edge when I folded the tape and ironed it, before sewing. By “I found it easier”, I mean by not doing that it is close to impossible to sew it nicely and with it ironed, it is just really difficult. I pined it in place every 6 inches or so, as I sewed the edge. You can’t pin too far ahead, because the tape adjusts length a little as you sew. This edge will also contain one of the exposed reflective tape ends.

Below are the finished side pieces, zipped together. The left side with the flap laying down as it will normally be to protect the zipper from debris and water. The right side has the flap lifted to show the zipper.

To finish the large side piece, I ran a second stitch along the zipper. I again used the zipper foot for one and regular foot for the other, to maintain consistent spacing. I then installed the two zipper pulls. When the pannier is closed, the two pulls will be together. It will open like a back pack, with the two zippers pulling away from each other to make an opening.

The next step is cutting out the front panel and joining it to the smaller of the side pieces. The dimensions for the front panel are 19″ x 13.25″ (18″ x 12.25″ finished). Again, you want to cut out the shorter dimension along the weft of the fabric, allowing the stronger warp threads to be vertical in the pannier.

After the piece is cut out and heat sealed, you join it to the shorter side piece on three edges, leaving one of the longer edges exposed to join with the back/bottom piece. I lined up the pieces at the tip center, but sewed to as one long seam with two turns.

Below is the finished side and front joined together. All that is left is to sew in the back panel pouch, join the back on, cut the back panel, bent and install the aluminum support, and install the mounting hardware. In other words, we aren’t even half way there yet.

I wanted to add a mesh pocket for holding things I need while riding and drying wet stuff. I could have done this along with the side seams to the front, but I wanted a smaller pocket. I also wanted the bottom of this pocket to be a few inches above the bottom of the pannier to keep it from sagging down and possibly dragging in turns. Both of these made sewing the pocket on a challenge.

My sister came over and got excited about the project. Ruth is more experienced at sewing than I am, but this the first “industrial” sewing project for either of us. She helped me figure out how to attach the mesh pocket. I used elastic across the top, folded over and stitched. She sewed on the pocket with the same cross-grain ribbon I used on the zipper cover and mitered edges at the corner. There were a few places that… umm… missed the tape. But she re-did those. I’m going for functionality, not beauty. Beauty wouldn’t be bad though. She sewed them on the right side,

In all fairness, I was a fairly tough with the low power of my machine. If I keep up this type of work, I’ll want to pick up a lightweight industrial machine. A machine that sews straight with plenty of power is the best option. We didn’t pull the elastic along the top enough with the first piece. Sewing down elastic takes out some of the retracting capability. One pocket will be slightly more loose than the other. The other lesson learned is that it would have been easier to sew on the pocket before sewing the front to the sides. On my second bag, I sewed the netting along with the front and side/top seams. It turned out cleaner and was MUCH easier.

I cut back/bottom piece at 19″ x 21″ (finished 18″ x 12.25″ back and 18″ x 7.75″ bottom.) Again, this was heat sealed all around the edge. The warp ran along the 21″ direction.

Before sewing onto the sides/top, I wanted to put in a pocked for the stiffener. This was cut from lightweight black nylon and sealed, 19″ x 13″. The sides of the pocket will be sewn into the seams, but I rolled over and sewed the top and bottom to the Cordura.

If you have done much sewing, you know there is that one time when everything is going right. You have been fighting seams all day and this seam is the best one so far. It is straight and the fabric is laying perfectly. That only means one thing, you bobbin just ran out of thread.

The sides of the back/bottom piece are sewn to the exposed edges of the front/sides/top piece. I centered the sides/top piece along the top of the back/bottom piece and sewed that first. This distributed the sides evenly.

These are all simple seams of keeping the fabric aligned and sewing at the right offset. However, because of all the hardware on the individual pieces, it takes some time.

Here the final seam being sewn to result in a finished pannier. Well the sewing is finished anyway.

Under the side pocket, you can see a small strip of reflective tape. Were I smart about it, I would have sewn this reflector along the entire edge of the front piece and into the seam at the side. This would be a larger reflecting surface and eliminate the need to fold over the ends of the tape to sew.

The attentive reader might also have figured out that these pannier could be made with a single piece for the back, bottom, and front. I had thought of this art first, but decided the likely hood of me lining everything up correctly with essentially two “U” shaped pieces of fabric (with the sides/top and the back/bottom/front) might be zero. My main concern was the unknown zipper seam offset. This would vary the thickness and make the bottom piece width vary. However, if you sewed together the side/top pieces and them measured the finished width, you could easily create a one piece back/bottom/front.

I purchased a hook kit from Arkel for mounting the panniers to the bike. This consists of two hooks up top, with a cam locking mechanism that locks the hooks onto the rack rail. Then an elastic hook holds onto the bottom of the rack.

Use of this mounting method requires support inside the pannier. My dad had a piece of plastic that would work. It is probably HDPE or PVC and about 1/8″ thick. I used some cardboard to prototype the support size before cutting plastic. Below is a test fit on the bike.

I scored the plastic with a razer knife and then folded it over to break the edge, similar to cutting drywall. I used a jigsaw to round over the corners of the sheet, then I cleaned up the edges with sand paper.

The mounting requires two holes in the support panel. I locked the clips on the rack and positioned the bag where I wanted it to mark the hole positions. I used the soldering iron to melt through the back fabric and into the plastic, then drilled holes in the support. Last, I melted the hole in the back fabric to match the size of the drilled hole. I was careful to not melt into the nylon pocket material. After I tightened the nylock nuts for the hooks, I made sure to clean off any edges that might cut in the pocket.

The last design element I borrowed from Arkel is the support rod. This takes the force from the front of the pannier and distributes it to the back, where the hooks transfer the load to the bike. If this rod was not installed, the weight in the pannier would allow the outside edge of the bottom to drop until the contents stopped compressing and the top and front took up the weight.

The rod is 1/4″ 6061 solid aluminum rod. We started bending at one edge. First the piece that will go into the webbing pocket, next the section goes along the side, then the portion along the top, next the other side, finally the webbing pocket piece on the far side. The side edge length isn’t critical, as long as they are equal. They should be as long as possible, however, because that will reduce the angle it makes with the back. The greater this angle becomes, the more force is pushed into the bike, rather than just down on the hooks.

I sewed in the top rod holder first. This is the most critical one for positioning. For material, I use a light weight 200 Cordura, which I had on hand. It doesn’t match, but no one ever sees it. After cutting the piece, I rolled over and stitched the shorter edges before sewing it into place. Care should be taken to get this as parallel as possible with the back edge.

Make sure that when the piece is pulled out firmly, it does not reach the zipper. If it does, extra force will be focused directly on the zipper. I’ve talked with zippers quite a bit, they don’t like this at all.

The bottom holder consists of 3/4″ nylon webbing, which is folded over and stitched along the edge to form a pocket. You don’t have to get the exact length right, but you want to get the fold correct. Once you sew this portion, you can cut the overall length to leave just a small margin to sew it to the bag. To find the position for these, install the rod inside the top holder and mount the pannier on the bike. Fake some force in the pannier top and figure out where it needs to me positioned to get the top level with some force on it. If you didn’t get the two sides equal when bending the rod, here is where you correct any small problems. Just make sure to mark the rod so it goes in the same way each time.

Since my bag is much wider than the pannier I modeled this after, I wanted to beef up the support.  I cut and added the 45 degree webbing reinforcement when I sewed the pocket.  With that, I was done.  I put it on the bike and loaded it down to ride for a few days.  Then I started all over again to make the second one.

Post Script:
After my 70+ days on the bike, during my Trans-Am tour, I learned a few things. The overall design and construction was sound. The bags are pretty decent at shedding water and held up pretty well to carrying the bulk of my touring load. A few things didn’t work well.

First, I under estimated the tilt angle that I might need to make on the bike, after the bags sagged slightly with heavy load. I would use 60 degrees as a measure next time, instead of 45 degrees. Obviously, if you make them shallower, this becomes less of a factor as well. This was augmented by the second problem, the bottom drooped. Not all loads I put in there were a flat 18″ x 7″ pieces of baggage. I don’t think any were. This causes the bag to get close enough to the ground that I did touch a few times at speed. Cordura fabric is abrasion resistant, but they aren’t talking about pavement at 40 mph on a downhill type of abrasion.

My dad met me two times on tour and I had him bring some equipment to solve these problems. We glued some light aluminum sheet to the outside rear edge, where I occasionally touched down, to form skid plates. We also put some cloroplast (basically corrugated cardboard, but made out of plastic) into the bottom of the pannier. I oriented the channels along the short axis to keep the bottom from curving as much as possible.

The entire process was a great learning experience that I would only do again if I couldn’t find something commercially available close to what I wanted. It is nice to personalize things, but these bags were a great deal of work.

Post any questions or clarification needed in the Comments.