How to build a Custom Motorcycle Seat

The custom motorcycle hobby is HUGE, it isn’t just Harley Davidsons that are being modified these days. Enthusiasts are building custom motorcycles out of anything they can get their hands on. One thing that everyone seems to have an opinion on is what their seat should look AND feel like. Some are ok with buying a seat out of a catalog, slapping it on and calling it a day, but if you’re anything like me, the satisfaction comes from the process of building something custom myself.

I recently shared the story about my adventure to get myself my first motorcycle project; a 1952 DKW RT125 and hinted at my plans for the bike. The other week I finally got some time between my other projects to do something about the “beach cruiser” seat on the DKW. After staring at the bike for a while, I decided that the seat that came on the bike was far too large for the bike and sat too high. I think the German designers may have had a rider in mind that had one-too-many servings of schnitzel and needed an extra large seat to hold them. Aesthetically speaking I think it really looked out of place. I plan to keep the majority of my modifications on the bike reversible, so I opted to remove the stock seat and make my own from scratch (using Eastwood Tools of course!). I liked the general shape of the stock seat, but not the size, so I decided to use the original seat as a pattern when making the seat frame up.

I know some take a piece of sheet metal and bend it over their knee, drill some holes, attach some springs, and call it day when they make seat pans, but I wanted something a little more like the original. The old seat used round steel bar stock and some small diameter tubing to make up the frame. I started by stripping off the rubber seat cover and taking some measurements. I decided that the seat mainly needed some width taken out of the rear portion to make it the same width as the tank to look more proportional. I drew up a pattern for the seat pan and began the project.

I used some 1/8″ round bar to make the frame of the seat. I first tried to make the entire frame out of one piece, but it was extremely difficult to get the bends to all line up the same. So instead I opted to make each bend separate and TIG weld them all together to make the frame. I started by making the front “nose” of the seat first. I decided to use the bar grooves in the Eastwood Slip Roll to make the bends I needed for the seat frame.

After a few passes through the slip roll I had my first piece matching the nose of the original seat. I repeated that process as I started working my way back on the seat. I like to bend with a piece of bar stock that’s longer than what I need so I can cut the excess off to make the bends land in the same spot. As I made my pieces I laid them out on the pattern to make sure I was keeping the correct shape.

Once I got all of the pieces made up to form the frame I taped them in place. I then worked around the frame and fusion welded each joint together with the Eastwood TIG 200. Once I had the frame welded into the shape I needed, I found I needed to put a slight curve into the center of the seat to get the overall curve shape I wanted. I ended up using a torch to heat the center and bend it a little to get the gentle curve needed.

Next I cut out the pan for the seat using my manilla folder as a pattern. I purposely cut the 18 gauge metal a little larger than the pattern so I had some room for error. I then centered the pan over the frame and clamped it in place using a set of Eastwood Mini Weld Clamps. Once the pan was clamped I used the TIG 200 to lay a number of small welds to connect the frame and pan together.

With the pan welded to the seat frame it finally started to look like what I had envisioned. I removed the excess metal off of the seat pan so that it was flush with the frame with a flap disc and an angle grinder. I then welded mounting tabs with studs on the bottom of the seat and attached the seat to the original seat bracket. With the seat mounted up, I decided to move the seat back. I used the front hole on the seat bracket and mated it to the rear hole in the frame. I then dropped the back of the seat bracket down to get the seat position a little lower. After mounting it all up I have made a custom seat that sits lower and looks more proportional without modifying the bike in a way that it would be difficult to return it back to stock.

With the seat mounted up I checked my seating position and it feels a lot less like a bicycle and more like a motorcycle. I definitely will need to make a bobbed rear fender that will keep my rear end from getting caught in the tire, so that’s one of the next projects. I plan to make a new set of bars with the help of the Eastwood Tubing Bender next. The new seat and the bars I plan to build should get the riding position more how I want. Slowly this old bike is taking shape. Watch this space for future updates.

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