New to discs. I'm assembling parts for a gravel bike, Force Axs ETap. The bike will be non technical rough roads and smooth pavement.

I have never dealt with discs. I have centerlock wheels and flat mount frame and understand that. I plan to order Sram discs in 160mm and was planning to use Sram Centerline X discs, being on a mid-pricepoint. Then I see sram marketing a more extensive disc, the Centerline XR as being for the Axs groups. Then I see the X actually listed as MTB discs... Then I see some list then as road or mountain.

​​​​​​So the real question is: what distinguishes an MTB from a road disc and should I be concerned about that?

It looks like they're putting more material on the road rotors to deal w/ heat better. Both of them have stainless rotors on aluminum spiders. I should know this but I don't...it looks to me like they both use the same depth pads, I've never had any problems using mtn rotors with road calipers/pads. I wouldn't worry at all about mixing and matching.

Road rotors have an alloy and steel sandwich construction to dissipate heat better. Road pads are finned for head dissipation, also. The factory gravel bikes I've seen use standard steel rotors.

There is no difference outside of marketing that distinguishes mtb from road. Unless you are descending long steep hills or mountains, any disc will do, although Id pass on the cheapest discs that doesn't work with sintered pads. Usually you pay extra for light weigh or increased heat dissipation, like in the Shimano icetech sandwich rotors. The cheapest one is the slx mtb rotor, but most likely you be fine with solid steel rotor. Brakes just as well.

Your planned riding seem it will place low demand on the brakes so any disc should be satisfactory. The plain SRAM Centerline should be plenty and the Centerline X a more expensive option. I see no reason to go more upscale.

Not sure where you're getting your information but it's all wrong. Shimano rotors have an alloy core, SRAM do not. Both Shimano road and mountain pads can be had either finned or not. SRAM does not make any finned pads.

Shimano. It's not all wrong, just incomplete. I just did some work on a Domane with Ultegra Di2 yesterday and the experience was filling my head with all sorts of inaccurate information.

Thanks all for the advice. With my weight and level of riding, I just won't overthink it too much (which is a bad habit I have). In obsessively surfing the net on the subject the past day or so, I see gravel bikes outfitted oem with both mtb and road looking rotors. I also saw that some tdf riders used Shimano XTR rotors recently instead of Dura Ace, for what reason the author didn't know, but apparently with no ill effect. There I did overthink it, but will stop now.

Thanks again.