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It does matter as im interested ... I have done fairly decent sized descents and not had an issue, you cant post in a forum and not expect questions :')
Rhobbs-
I have done fairly decent sized descents and not had an issue
That's not really a sample rate. Subjective experience aside, as many on here have done the same.
My experience stems from a fleet of bikes, set up evenly, maintained regularly, ridden over varying terrain in diverse conditions.
Statistically, there was a higher failure rate from 140mm rotor equipped bikes in relation to 160mm equipped ones.
Whether this proves causation, I'm not a statistician so I can't tell you. Maybe the 140mm equipped bikes had brake dragging noobs on them and that fucked them up and vice versa. -
In my experiences from working in a workshop, 140mm rotors need regular replacing due to more wear despite pads having plenty of life left (resin) on top of the warped.
When quoting bike for a service, I always put down a recommendation of going for a 160mm over 140mm, it’s helpful that the flat mount standard mean I can just flip the adaptor the other way roins to use bigger rotor.
AFAIK, only Shimano happily recommend 140mm rotor in all but the largest cyclists, and they spend a lots of R&D in designing their 140mm rotor to dissipate as much heat as possible.
160mm mean better heat dissipate, longer lasting, and less likely to warp especially the floating rotor design.
TL:DR; I concur with @Chak finding, from customers bike to personal bike.
Chak
edscoble
Does it matter? Will it justify brake fade due to poor heat dissipation?
The bikes running 160 up front of all Shimano levels didn't fail. 140's on the same brake setup did. Not all, but enough to raise questions.