What do you reckon I should go for on an AM/DH build? Would there be enough of a weight difference between the two (larger disc + adaptor) to not go for the bigger brake? I have a 203mm on the front and it seems the braking power is about the same as the old 160, but it doesn’t get as hot.

what is AM/DH build? If it is an all mountain bike 180, downhill bike 203

Uh? Is that a question about whether you want more power, less weight, or are worried about it boiling?

Personally, bigger is better. I can definitely tell the difference between a 160 and 203mm rotor, but if you can’t notice the difference why worry?

185 on the back is fine IMO, given how easy it is to lock out with decent brakes. But if weight isn’t an issue, go for it — more is more. 🙂

Any decent rear brake should be able to lock the rear wheel at any speed with a 160 disc – the bigger size gives you more heat dissipation and modulation as well as more power – but you can’t really use the extra power on the back

I run 203mm F+R on my DH bike. The only time they’ve ever overheated to ‘fail’ is a top-to-bottom-non-stop at Pila, and then it was only 100-200m from the road at the bottom. Standard XT with SUPERSTAR pads. Yes, Superstar, and I’m not dead or owt.

I run 160mm on the rear on everything else.

TJ +1.

I have a 203 on the front and a 160 on the back or my (trail) bikes.

I found that too much braking power on the front causes forks to dive more.
Bigger rotor on the back balances it a bit.
I run 200/180 on one bike and 180/160 on the other..

I’m running 203s each end on the trail/am/xc/whatever bike, simply as it’s all I had available.

225/205 on the DH bike though 😀

what is AM/DH build? If it is an all mountain bike 180, downhill bike 203

It’s kind of a bike that’s built for riding downhill but I want to take it up a few climbs as well! The superstar site suggests there’s a 50g difference between 180 and 203 rotors.. doesn’t seem like much so may just go for the bigger one.

If weight is your concern then I would not really worry about it, on a bike like that you would really not be able to notice 50g of difference.

I had 203 rotors front and back on my Uzzi. Changed the rear for a 180 because I prefer to have a similar feel on the lever front and rear. Sure I can modulate with the bigger rotors too, but with 203 on the rear I required a completely different kind of force for the rear brake then the front one. Now both require a similar force which feels more intuitive.

I’m pretty sure I would have gotten used to it, but I made the swap and felt very happy for it.

As above, will make **** all difference

will make **** all difference

so why the different sizes?

….because it does make a difference on longer downhill trails that require lots of braking. In the alps this last weekend I ‘lost’ the rear brake a couple of times (lever back to the grip) from over heating using a 180 disc. I swapped for a 203 and didn’t have a problem after that.

203 it is then, cheers guys 🙂