A large waterproof container that fits in the S2's frame.

Preface

In this mod, I make a wooden frame that fits inside the S2's frame and screws into the mounting slots. Two side panels are fitted on each side to make a large waterproof space for my custom batteries and controller.

Pros:

• Reversible, no bike damage

• Highly customizable

• Future-proof, large amount of space

• Can rigidify the frame

• Cheap

Cons:

• A bit heavy, your choice of wood and plank thickness is critical. Mine is arguably not the lightest but very sturdy

• Lots of work and tools required

• ⚠️ Depending on the width you choose the box might block the chain from switching to some gears. A max width of 15cm will restrain the chain to the smallest gear only.

Parts

1. Wood plank (min 1.6m). I used a 2.4*15*200cm slab of unidentified wood and had some left over.

2. Extra little plank. 10*31*1.7cm that fits on the pedal area and provides a flat surface for the assembly to sit on.

3. Side panels. I used two sheets of acrylic that I rounded with heat on the top and bottom and cut to size. Metal, wood, or plastic will also do just fine.

4. Hardware, screws. Lots of them. Remember to get wood glue, wood screws, and M4 screws for mounting (the bottom ones will need to be longer). 

Optional

5. Rubber or some other seal, That will sit between the frame and side panels (optional).

Assembly

About width: Anything from 10 to 15cm will work. I chose a 15cm plank width because it's a standard minimum width for the batteries I want to fit inside. Choose your width depending on what you need. With the max 15cm width your side panels will have to be quite thin. My acrylic ones are ~4mm thick.

About mounting points: On the bottom, there are two usable screw holes, the two centered ones (the off-center back ones are right below the vertical piece and hence are unused). On the front there are four usable ones although a mudguard uses two of them so keep that in mind. On the top, all four screws are available.  I won't be talking about these in the build steps as it is up to you to choose which ones fit your needs. My setup uses the 2 bottom ones and 4 top ones.

1.  Prepare the little support plank. It should sit centered between the front bend in the frame and the little fender mounting point in the back. You should make two indents for the unused off-centered screw bumps on the bike frame to slot into. This way it lies flat on the frame in the back and on the pedal shaft in the front.  This piece will NOT be attached to the main frame, it will be placed first and will allow the frame to slide in and rest on top of it. both the frame and this piece will be held in place together using the two centered bottom mounting points.

2. Cut and assemble the wood frame as detailed above, test fitting and adjusting during the whole process. On each joint, use a LOT of glue as well as 2-3 wood screws. This is to make them sturdy and waterproof. I suggest starting with the bottom piece and then the back and top since they are 90-degree angles. Once these three are assembled and test-fitted you can take proper measurements for the front diagonal which is the trickier part.

3. Test fit the assembly. First place the small plank on the bottom. Slide the frame in from the no-chain side. The bottom mounting screws run through the frame and the small support piece.  The top and front (I do not use the front ones in my case) run through the frame only.

4. Finish the wooden parts by sanding and varnishing or painting. In my case, I applied a layer of wood glue, then spray-painted and applied wood glue again on the wooden parts for protection and water resistance.

  5. Cut and/or shape the side panels.The minimal setup would be to cut wood sheets to the shape of the frame and paint them. 

Mine are made out of two acrylic 4mm panels. I bent them so they cover the top and bottom edges of the frame and left an overhang on the front and back side, purely for esthetics. Then they are placed over the frame and I made wholes using a soldering iron with a wide point for the screws at regular intervals. They were then spray painted black. Doing a complex shape like this might require some minor cuts and adjustments to fit the bike's frame nicely.

6. Mount the side panels. Mine are mounted with black woodscrews all around the frame roughly 5cm apart. If waterproofing is a concern for you now is the time to add some rubber to the edges of the frame, that the panels will squish. I cut strips out of an old tire tube but you could use something off-the-shelf or silicone. Keep in mind you will probably take the no-chain side panel on and off a few times since it is the most practical one, the other one can be made permanent.

You might want to use hinges and some locking mechanism if you intend to use it as a storage space.

Optional Steps

Air vent / Cable hole

Since my setup is used to fit a controler-battery combo I needed a hole to pass the cables. Something that would be rain and splash resistant. So I bent and shaped a piece of acrylic to cover a hole in the upper back of the frame.