Here's my idea for a front brake. You can easily get all the parts at your local hardware store. The red coloured parts are part of the brake system, and most of it is inside the stem. It basically goes from the top of the crossbar and through the stem (drill a hole through the top of the crossbar, and stick the threaded bar through). There's also a spring in between the top pad that you press down and the top of the crossbar to make it go up automatically when you let go of it. And the pad on the bottom and the one on top are up to you to design and make however way you like best (it's not that hard to find materials for it). The plus to this design is that there are not cables involved or brake levers, so it's nice and out of the way. The downside is that you have to move your hand to the middle of the bars to push the brake down, and you also can't use a compression system with it, but that's no big deal at all.
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