I'm showing in more detail the aluminum strip chain cover from my Dawes SST Review thread. This is amazingly easy to construct with basic tools considering my lack of crafting skills. since this was my first try there are several things that can be improved, or just constructed better by someone with skills. It took me a couple of hours, much of it spent on head-scratching and dull drill bits.

It is a partial chain case, just a strip around the chain to protect my pants and to keep the worst of the elements from the drive train. It works pretty well for that:



The cover is an aluminum carpet seam strip. It is 1 1/4" wide which is just about perfect IMO, although I think +/- 1/4" would also work. I started with a 10 or 12 foot strip from Home Depot to make fenders with ($14), and had some left over so this was mostly zero cost. I also used a couple of nuts and bolts, a re-purposed reflector mount, some old inner tube rubber, and a few zip ties.

The only difficult challenge is that in attaching to the frame, the positioning needs to be very precise in back, and solid in front. It needs to hang straight vertically without much movement in normal use. I went for the simplest idea.

But first, bending the cover into shape. I just laid it against the chain ring and carefully bent it, using my thumbs to make tiny adjustments where needed. You just look at where it begins to diverge from the curvature and make a little bend at that exact spot. I taped it in place to mark where I wanted to cut it in back.



After trimming the back ends and bending around the cog it's laid over the cog loosely. Notches need to be cut out for the seat stay and rack strut. It looks like a lot of clearance here but by the time this is done it's drawn in quite a bit so it's best to leave an inch of space around the cog. This isn't the best place to join the two sides I think. Doing it over I'd have the break somewhere behind the rack strut, to make it easy to open up and to adjust. With some notches cut out these don't have to be precise because they're going to be padded with rubber.

Next the front mount. It's hard to see here, but it's just a reflector clamp and the guard is clamped tight over the plastic swivel part of it. Large zip-tie through the guard and around the clamp bolt. It's easy to position the chain guard precisely by just moving the clamp around.

After getting that solid attach the back. I overlapped the ends, drilled and bolted (while having it off the bike ). Both ends are covered with a piece of inner tube to prevent scratches and rattling, and I put thick rubber in the notches between the struts and stay, and the guard. You'll also see a zip-tie around the stay. Unfortunately that's critical because tightening it there, against the rubber, sets the angle that it hangs at and positioning the bottom at the back:

At this point although it should be attached pretty well, it's still wobbly in front and may not be in the right position on bottom, towards the front. The simplest thing to do is brace it from the chain stay. I originally tried it from the drive-side stay, but moved to the non-drive side to make it more solid and easier to work with: Making a clamp from a trimmed-off piece and eyeball it in place for the bends, the critical point is having vertical sides on the clamp part and enough rubber inside to conform, which keeps the clamp rock solid: This part can be improved I'm sure, but doing it this way is very easy and solid, and doesn't look all that conspicuous.

That's all there is to it, simple and effective. I'm hoping this inspires someone to improve on the basic idea. For my part I'm pretty happy as is, but I'm mulling over adding a vinyl cover for a more full enclosure. Maybe someone will take up where I left off here.