A top cap for a bicycle with a 1 1/8" threadless stem. Super-clean solution if you want to mount an iPhone on your bike. This leaves the handlebars uncluttered for your hands or for other accessories or just for the sake of admiring clean, uncluttered handlebars.
These replace old plastic cable guides that are commonly missing on old Cannondales. By gluing the posts on the inside of the holes you don't run the risk of ripping the paint from the frame like you do if you just glue on old guides that are missing their posts. My suggestion is to turn the frame upside down and put a generous drop of glue inside each of the holes - then insert the cable guides and allow the glue to dry with the frame upside down so that the glue stays puddled around the cable guide's posts. If you have bits of plastic from the old cable guides rattling around the top tube like my friend did, drip a good puddle of glue into the top tube and shake it around until the bits get stuck in the glue.
Albeit not as clever as the top cap mount, this mount gives you a smart, simple, secure way to mount an iPhone to a bike with a quill stem. It uses three zip ties; one around the stem and one on either side of the handlebars. Designed to fit most standard quill stems, 80mm or longer.