i’m just nailing together my sb66. it will be used for welsh trail centre riding and hopefully a trip to the alps later in the summer (i have a hardtail for everything else).

i have the following sets of rotors:-

Uberbike 180 / 160 floating rotors
Hope Saw 203 / 180 floating rotors

the calipers will be new Deore XT 985’s with finned pads.

i’m a pretty crap rider, so often drag my brakes on the downhill sections (as i get scared easily). i’m also pretty heavy (14 stone).

i’ve been running 180/160 combinations for quite a while and always felt i could do with having a bit more braking power. i’m not really in a position to switch to 4-pot calipers, so would the Hope 203/180 combo work better do you think?

the fork will be a new pike btw.

cheers

as youre using 2 pot calipers then increasing the rotor size will help improve braking and also dissipating the heat built up from you dragging the brakes on descents. so yes go for it, but be aware that the larger rotors will add weight to the wheels.

btw – i’m pretty sure 985’s are XTR not XT

I’d try both tbh, doesn’t take long to swap. Have you already used those brakes? Not generally short of power, new Shimano!

I tried them once on the FTM Carbon (I only rode it once) and was a bit underwhelmed, hence the thought to go up to 203 on the front.

I know there is a weight increase, but on a SB66, an extra +/- 75g of unsprung weight isn’t going to change my world as I’m unlikely to be chasing 25lbs as I did on the FTM.

203mm each end

big as you can on the front, a little smaller on the rear for balance. If you do still get heat problems (and your frame can take it), go even bigger on the rear.

IMHO of course

Can’t fit a 203mm rear rotor on the SB66.

203/180, I see no logical reason why you wouldn’t.

Good luck with the SB build, I loved the way mine rode but it destroyed bearings as water is able to track straight down the seat tube into the switch (and not escape) and the lower chainstay snapped.