Originally Posted by
veganaise
Off the top of my head, two ways you can do it:
1. Use a modified BMX upper giro, a la
FGG Tutorial. Kind of a kludge, in my opinion, but if it works, it works. Plus giros are pretty cheap.
2. Get a
Problem Solvers 2:1 Cable Doubler (pdf). They're a bit pricey, but the right way to do 2 levers to 1 brake. Some other company makes a cable splitter aimed at tri/time trial bikes that's priced about the same level as the PS Doubler but the name escapes me.
EDIT: The forgotten company is Jtek.
Scroll down.
Someone over at Bicycle Mechanics said this would be doable with cross levers. The FGG Tutorial solution seems sketchy. I have to wonder, why couldn't I just set up the cross levers with one primary and one inline, as though it was the aero/cross combo on one side?