Originally Posted by peripatetic
I knew it was weird! I have the same "double-pulley" design on my SunTour 6-speed-equipped Miyata. I shortened the chain recently, because it was way too long, and now I've had two near-bad 0 mph crashes because the chain keeps falling off of the chainring. Would this be some other kind of 'worn cog' problem, you think? Do I need to change the freewheel? It's falling off of the front, not the back.
I find the shape/look of the derailler really ugly.
Incidentally, I have another old bike with an APX derailler on it (7-speed), but it doesn't have the "double-pulley" design.
I'd replace the derailer... I have an ARX derailer from another year and it's a normal design, it's meant for a double.
The double pulley idea sounds kind of neat, but it must not have been very good in practice since they only made them for a couple years.