I want to retrofit my new to me trek 8000 (2000 or so) with hydralic brakes. Which size do I need 203mm, 185mm, or 160mm? It already has the predrilled/tapped holes (x2) on the front forks and rear, so I'm told it's ready to accept them.
I'm not so sure on that exact model Trek, but given the 2000 model year,
I'd guess it has the frame clearance for the 160 in the rear, it's plenty for the rear and light too.
Normally with the 160 rear, I like to set people up with the 185 front.
That combonation is light enough for XC use and gives a really good feeling and powerful brake set when set up propperly.
Most forks with disk mounts will accept the 185s with no problems.