Ever been working on a bike and realized that you need a part and dont have it and think "oooo I can make that" , simple things like spacers,BB sleeves and such,even home made parcel racks, as the old saying goes "Necessity is the Mother of invention" I made a peddle out of WOOD (wot was I thinking ?) lol, wot have YOU done ?

Chainring spacers. Never have them when I need them.

Shifting knuckle bell crank and shift pin for New Departure 2-speed.

The guy at Dover Cyclery is pretty good with that kind of thing. I take a problem in to him and he rummages around in his box of junk and hands me something for some totally other purpose ans says "file this corner off and hit it here with a hammer" and gives me the part for free. Good guy.

My grandpa could fix anything on a bike with fencing wire and chewing gum !

I came up with a drop bolt workaround for a rear Gran Compe caliper by drilling out a couple of pieces of 1/4 inch aluminum bar stock.

The spacer for the center bolt is a plastic bushing from a DiaCompe safety lever.

Inspiration by Sheldon Brown.

Yeah, I've done that.

My most successful projects was many years ago, when water bottle cages came in only one size, I made one that fit a one-liter soda bottle. It was made of aluminum bar stock bent into a kind of helical shape. It was quite pretty, and I used it for years.

A less successful, though more ambitious project, ca. 1982: I mounted a downtube shifter to the stud that holds the extension levers on old Weinmann / DiaCompe brake levers. It actually worked, though never quite well enough. This was before the days of Suntour Command shifters, brifters, and the like.

Also eyelet adapters for an eyelet-free frame (using the triangular hole in the campy dropout); brackets for headlights, not to mention whole headlights, tail lights, etc.