ADAM31

I have a specialized tarmac 2021, a metal on metal sound popped up about a month ago. I thought that it was time to change my cassette and chain which it definitely was. I thought for sure that the noise would go away with that fix, but it still remains. It’s most noticeable when I am climbing out of the saddle on steep incline. I am starting to believe it’s coming from the disk brake pads possibly just slightly rubbing the disk as the bike is moving more side to side while climbing. The brakes look pretty aligned from what I can see but is it possible that they are worn out and moving just enough to hit the disk making the metal on metal sound. Otherwise the only thing I can think of it’s coming from the front small chainring. I trued the rear wheel a couple months back, but maybe the wheel is out of alignment a bit and causing the brake pads to rub on the disk.

Unca_Sam

If you have a repair stand, put the bike in it and focus on the brake rotors. I would agree that the sound you're hearing is probably from a slightly out of true rotor. You could put a line from a marker on the rotor and see if the pads rub off the mark where it's rubbing on the pads.

An out of true rim won't affect disc brakes; the rotor is at the hub. IF the disc is not in plane with the caliper, check to make sure the wheel is secured properly in the frame.

Iride01 

Check the lock ring on the center lock brakes. Both of mine were loose after the first year of use on my 2020 Tarmac. The rear more than the front.

ADAM31

it was loose on the rear but the noise remains…know I am believing it’s in the bottom bracket

Iride01 

Did you buy the bike new? Did you ever take it back to the shop to get that free inspection and adjustment they may have told you about as you were leaving the shop with the bike.

Even if they didn't you should go back and let them look. Might be something that needs some authorized dealer eyes on it just in case there is some warranty issue involved.

Personally I think it unlikely to be the BB. And if it is, then certainly that must be a warranty issue unless you've been messing with it. BB's don't wear out in just a few years. Unless you are doing 20,000 miles a year.

Have you had the bikes rear wheel off the ground so you can turn the crank, shift and hear what's going on when? If you don't have a stand, then hang the nose of the saddle on the corner of a high table or something. Or hang it by the top tube on the corner of a table.

You might make a video with sound and maybe we can hear the noise if you post it.