Wiring multiple shifters

[capner2112]

I'm in the process of manufacturing aerobars for my 79 World Sport. I intend on making bar-end friction shifters for the aerobars also. When I install the bar-end shifters, I would like to keep the current stem-mounted friction shifters in place cables and all in working order. That way I can shift when in and out of the aero position.

Any suggestions for connecting two cable lines that would make this work? I'm open to any ideas. I've thought of a second cable stop and some sort of clamp to connect the cables.

Also, I run a 5-speed in the back on an old SunTour derailleur. Would this work with more speeds like 7 or 8?

[nfmisso]

there has to be a two way (push-pull) linkage (or two cables) between the bar end and stem mounted shifters. And the backlash (play) must be very very low.

this will only work with friction shifters, not indexed.

the number of speeds is irrelevant.