Road disc brakes 140 or 160 or mix for CX

[Erik_A]

I want to add Avid BB7 road disc brakes to a Lemond Poprad disc cyclocross frameset that I bought as a frame only. I hear that some of you guys are running 140 rotors on the rear and 160 rotors on the front. This is my 1st foray into disc brakes; how do you decide on the rotor size? What are the pros and cons? Will the hardware take either 140 or 160s? I am a big guy 220 lbs, so I was assuming 160 size rotors (the bigger the better, right).

[tuscanyswe]

Id go 160 both front n rear. Theres really no pros with 140 rear except the grams saved. Perhaps as many as 20..

[aaronv]

What I have encountered is that some frames will only accommodate a 160mm rear rotor or only a 140mm.
See http://www.somafab.com/archives/product/double-cross-dc for an example of a frame that only takes a 160mm.
Best to check your frame spec to avoid buying the wrong rotor.

[David Kirk]

I'm using 160 F and 140 R on my cross bike and I weigh 180. The set up works very well with more than enough power and great modulation.

Dave

[xjoex]

I have been running 160 F and R on my CX bike for the past 5 years. No complaints. I weigh 145.

https://lh3.googleusercontent.com/-eEC6zXfzdIM/UEGUYM-ZVcI/AAAAAAAAGgk/H9jEbJH8M5A/s640/photo%25281%2529.jpg

-Joe

[EricEstlund]

Thread drift- do any of you have real experience with the Hayes CX-5?

[Liv2RideHard]

160 f and 140 r on my hardtail race bike. No complaints. Plenty of stopping power for me, even on the gnarliest singletrack Pisgah has to offer.

[pdmtong]

if you can fit a 160 in the rear without issue I would. as noted, a 140 is doable so its just preference.

simialrly my mtb came with a 160 in the rear and I replaced it with a 185..nice to have in some situations with no downside but a few grams in rotor weight.