How could I forget to mention the bicycle is a good invention

July 5, 2008 2:20 PM

I'm building a two-wheeled cargo trailer for my bicycle, and I'm mounting standard caliper brakes on each wheel of the trailer. I want to control both brakes with one handle i.e. I squeeze the handle, and both calipers close. How can I set this up?

My first idea was to use motorcycle cable housing and run both brake cables inside that, but I nixed that idea because I'd have to figure out a way to attach both cables at the handle.

I'd prefer to buy an off-the-shelf "two-caliper-one-handle" setup, but I can fabricate parts and build a setup if someone has an engineering solution or design idea. Anyone?

posted by optovox to travel & transportation (9 comments total)

If all you need is a design idea, you can buy three-way cable holders (where you secure them all to posts and then clamped, basically). If you mount that with the two brakes evenly tensioned, and connect the third cable to the handle. Squeezing the handle will put an equal amount of pull on each of those other two cables.
posted by klangklangston at 2:34 PM on July 5, 2008

something like this for the lever?
posted by contraption at 2:35 PM on July 5, 2008

I was going to say a cantilever-brake cable-hanger used as a splitter, but contraption's idea is better (might be heavier, but definitely simpler and more failsafe). I think I've seen similar gadgets used w/tandems, too.
posted by box at 3:16 PM on July 5, 2008

The Dia-Compe 287T appears to be the drop-bar equivalent (there are some other potential ideas on that page as well).
posted by box at 3:21 PM on July 5, 2008

I always called those two-cable levers "tandem levers" --I believe that they're usually intended to pull both the front and rear calipers/cantilevers when a separate disk or drum brake is installed on the rear wheel. I don't think I've seen a tandem set up this way postdating maybe 1985, but if you ask around at your local bike shops someone might have one in their stuff bins which they'd be willing to part with for a song.
posted by pullayup at 5:16 PM on July 5, 2008

The problem with a two cable pull is balancing. Unless that trick handle accounts for that you can end up with unequal brake application. All you need is a balance bar like is used for most parking/emergency brakes on cars. The lever pulls a single cable which connects to the centre of the bar and each end of the bar connects to the brakes on each side. The balance bar automatically takes up the slack on each side giving equal pressure to each drum/caliper. Something like this (probably expensive) dual e-brake cable along with a single cable to your lever joined at the shackle. On the cheap it's pretty easy to make with a piece of channel that you drill three holes in. The two outer holes just pass the cables and the centre hole is large enough to generously pass a threaded rod to account for adjustment and provide a pivot.

This is the setup I made for my truck. You can see the two brake cables coming in from the left. The threaded rod in the centre is attached to the brake pedal at the other end via a welded eyelet and some cable hardware. The balance bar in this case is the factory piece.
posted by Mitheral at 5:51 PM on July 5, 2008

old-school mountain bikes used a pulley to balance the pull between the two sides. you could easily find one of those, either on a junked bike or the parts bin of a bike store. ask the mechanic if they have any lying around.

use a single-pull lever and run the cable back to the trailer. mount the pulley on the end of that cable. join the ends of the caliper cables on an offset so they don't run through the pulley using a connector with slots for the heads of the cable (can't find a photo of that).

the principle is the same as mitheral's setup.
posted by klanawa at 8:51 PM on July 5, 2008

It definitely makes sense to combine the two trailer breaks into one balanced pull. But, would you be substituting that control for the rear brake, or are you looking for three controllable brakes?

The dual control lever looks pretty neat.. Inspecting the picture reveals that it has independent barrel adjustments for tensioning the two cables separately, which is nice, but is it designed for V-brakes or canti?

Finally, Mr. Brown talked of using a friction shift lever for the drum brake on a tandem. Might be a useful idea.. I've never felt the need for a trailer brake while riding, but a lockable brake for stops on hills would be great.
posted by Chuckles at 11:58 AM on July 6, 2008

BMX gyro head sets split the rear break cable into two for the cable to gyro interface.
see some bmx catalog

Something like this would lack the balancing of Mitheral and Klanawa suggestions but it is a good part to know about.
posted by bdc34 at 11:18 AM on July 7, 2008