Bicycle Brake Cable Splitter

thingiverse

I'm in the process of building a lean steering, recumbent trike and and need to split the control from my front brake lever to both the front, mechanical disk brakes. I've only got two hands, but a recumbent trike has three wheels and three brakes. I need one hand fro both front brakes and one hand for the rear. Yeah, I could buy a dual pull brake lever, but I have 2 perfectly good levers in my junk box and the point of building a trike is that I don't have a lot of money, otherwise, I'd just buy a Trisled from down the train track, in Morwell. So, how does a brake splitter work? If you look at the first picture, you can see the cable sheath from the brake lever entering the single hole on the left, and 2 brake cable sheaths leaving on the right, one for the left-hand front brake, one for the right-hand one. This bit's pretty straightforward. The cutaway view (second pic) shows the internal slide. Threaded through the side holes in the slide slide are 2 road bike cable inners. These have to be road bike cables to keep the lead stopper small enough to fit. Mountain bike cable stops are 8mm diameter and 6mm thick. They could be accommodated in a remix, but why bother, road cables are just as strong as mountain cables. Now the cable inner from the lever is threaded through the middle holes of the slide and housing. Make sure you have the sheath cut and fitted to this cable already. Insert your M3 x 8mm clamping screw, clamping washers and nut into the slide now but don't tighten this all the way just yet. At this stage, we slip the slide into the housing until the slide sits just enough inside the housing that the lid can be fitted and the middle cable can be clamped tightly with the 3mm screw. Finally, we fit the lid by threading the 2 output cables through the outer holes of the lid and any excess input (lever) cable through the middle hole, slide the lid up to the body, slip 2 more M3 square nuts int to slots on the sides of the housing and fit two M3 x 30mm screws, tightening them down to hold the lid in snugly in place. When the lever is pulled, the slide is pulled to the left and the excess lever cable will appear to shorten as it slide back with the internal slide. The output cables should also move back equally. If the brake lever is stiff at this point, or won't move, check for jams. Now, slip your sheaths (aka bowden tubes!) over the output cables and connect them to the disk brakes at your front wheels. You will need to have the adjusting screw at the brakes screwed all the way in with no spare thread and you'll need to take up any light slack by screwing them out equally until a nice brake feel is achieved, then trim the slacker of the two brakes a little more for good balance. It's quite likely that your front brakes will feel "heavier" than your rear, but that's because your lever is doing twice the work. Use locksmith's graphite to lubricate. Another use for this brake splitter is for running a single lever on a bicycle, say a track bike with one, seatpost brake lever, or as a disability aid for a partial amputee who still rides a bicycle. In this case, trim the 2 brakes so that the front does about 20% more braking than the rear, so as not to cause a lockup on the back wheel. I plan to print mine in carbon fibre impregnated PETG at 20% infill and 4 layer walls. Plain PETG may be spongy. PLA is probably not up to the task, especially if your trike or bike lives outside in the sunshine. Your mileage may vary. I recommend Form Futura Carbon Fil as even my shitty, bog-stock Ender 3 creates beautiful prints with this stuff. Photos of the thing will be uploaded later in the week, when I've printed it. At some later stage, install pics or video will be added. Remix as needed, maybe you're an amputee with a trike and need a 3 way split, maybe you're building a a 4 wheel pedal off-roader with "tank steering." Just please remember to give credit and remember, this is a non-commercial licence. No Etsy or other stores selling these, please. And factories? HANDS OFF!