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My riding buddy wants to swap the rear 180mm rotor on his 2017 Jeffsy 29” for a 200mm rotor (he’s quite hefty).
Tying myself in knots trying to figure out which brake adapter is needed.
The Jeffsy has a standard 180 PM fitting at the back so I assumed it’ll need a +20mm PM to PM (ie 160 to 180 front PM) adapter but I’ve seen some recommendations saying it needs a 203mm front PM adapter.
Can anyone confirm what adapter is needed? Ideally one that comes with bolts...
I assumed it’ll need a +20mm PM to PM
That should be the one if I've understood the situation properly. A lot of forks have a 180 mm post mount on the front so they use a +20 mm adapter to go to 200 mm.
Correct me if I'm wrong but doesnt it have a 160mm rear post mount using an adapter to make it 180mm sram set up, and the front already 200mm, personally I'd ditch the long bolts and cup washer things and buy 200mm hope post mount M and get some ti bolts. Theres not a lot of 200mm adapter options or rotors too, hope or sram centreline. +20 pm to pm only works if actual mount is 180 like 2018 rockshox yaris. Front & rear pm adapters are the same only IS are diff f & r.
Thanks robo89, that's really useful.
I also think you're right about having an adapter already. Mine's the 27.5 Jeff and it's a 180PM as standard but looking at a few pics of the original 29 model it looks like a 160 PM they fitted with a 180mm rotor and +20mm adapter.
The 2019 Jeff 29 now looks like 180 PM as standard.
So I'll need to get him a +40mm PM to PM...
RicB you've got me scratching my head now, I worked on one a couple of years ago, it definitely had an adapter on the 180 rear, maybe they change between sizes or carbon differs from alloy version