Hi,

I building up my new FS bike over the next 2 weeks and am wondering what size rotors to go for? I’m off to PDS so that will be the bikes first major outing. I’m thinking either 180/160 or 203/180. What do you guys think?

Thanks

How much do you and the bike weigh?

How strong are your arms?

How good at braking are you?

203/180 is what I use and it’s plenty powerful – but I weigh about 80kilos and (like to / can’t help but) drag the brakes.

Nothing wrong with having a bit more heat dissipation and braking power on the rougher stuff. PPdS might be ok on 180/160 if you’re a lightweight racing snake with huge balls

I weigh about the same as you. Bike will be hopefully about 25/26 lbs. I’m leaning towards 203/180 set up.

I’ve got 200/180 on my hardtail, 180/160 on my suspension mountain bike, 200/200 on my commuter/tourer (a result of transferring old Hope IS-mount calipers to a post-mount frame) and 160/160 on the CX(/road) bike – I weigh 93kgs. The stopping power on the tourer is awesome, even with narrower tyres, the modulation and the ability to drag the rear on long descents when fully loaded, without massive overheating, is great. My advice: unless you’re really concerned about weight, go for the largest rotor you can get on there – even if you don’t need the absolute stopping power, the control that a larger rotor gives is worth it.

You can never have enough braking power! If in doubt go 203/180mm. If nothing else, you’ll have decent heat dissipation.

Downsides of bigger rotors are really small- wee bit of loss of subtlety, tiny amount of weight. Pluses in the right circumstances are huge. Like they say, if in doubt, go big.

Go big as you’re going to France, you can always downsize when you come home and the mountains become hills.
I’m 90kg and pretty sure my bike is 180/180 although it might be 203/180 can ‘t remember. The Mrs runs. 180/160 but she’s about 30kg lighter than me and found that 203/203 on her DH bike was to much so went smaller and never went back