I regretted the suggestion of the 17 mm MC right away but it got away from me. I am always thinking the single disc MC isn't right for the dual set up. And I've finally come to realize that I've been wrong.
It's true the stock BMW dual disk set up on the S and other Ate bikes with dual disks used a 17 mm MC. If you go smaller there will be firmer and better brakes. I'm afraid if I go too small there will be too much travel and this is the other side of the coin that can really cause problems. Some riders do use a 13 so the single disk 14 should be OK. I would still check carefully. If you have warped disks the lever travel will be more and too small will be a problem. Since you already have the 14 I'd try to use this. Then you'll know where you want to go from there.
I like Kai Ju's twin hose set up. Much neater and less space than a splitter.
disston screwed with this post 09-25-2012 at 09:16 AM