Looking closely at the Alex rims on my Giro, I found very small cracks all the way around on both sides, plus between the spokes.

I took a look at the Alex rims on my road bike and nope...no cracks.

Hmmm....micro cracks in the finish of the rim or what?

Anyone else ever see this on their rims?

This is very common on some anodized rims. One factor is whether the rim was anodized after production, or if the extrusion was anodized before being rolled into hoops. Pre anodized suffers this kind of micro-cracking during the forming process. This is far less than ideal for most things, but braking would strip the anodizing anyway so it doesn't matter. However, I'd avoid pre-anodized stock if making disc only rims.

You can also get a similar effect after use because the aluminum flexes, and the anodized surface is more brittle and doesn't. You rims appear to be hard anodized, and that type is especially prone to this kind of surface checking. It's OK and will take eons to become, not OK, but if you're concerned, periodically use a wax/oil treatment applying with a rag against the spinning wheel, being careful to stay away from the brake track.

FWIW- Over the years I've had many rims with similar (non) issues, and have never had a rim structural failure of any kind except direct impact failures (aka crashes).

That would drive me crazy.. New bike ? I'd want warranty on them,,,

Older bike,,, time for a wheel upgrade....

I don't ride cracks of any kind even if the maker said I was safe..

I had a lot of problems like that on Velocity rims. My tires were too fat for the rims. Narrower tires fixed the problem. bk

I agree. I thought about it yesterday and will be contacting Bacchetta about replacing them.

,,,,,Also why is the spoke just above the nipple missing some finish ???
This made me go check spokes on two bikes,,,, Mine are not like that,,,Odd

It is time for a new rim. It is either caused from flaws in the rim, or rim wear from caliper brakes that people that dont like disc brakes says almost never happens.

Had a mechanic look at it yesterday. He said not to sweat it and the cracks are simply surface cracks in the finish.

See post No.2. Happy to see that the gloom and doom set didn't cause issues between you and the mechanic. I don't usually post this kind of "I told you so, but I was concerned, that people were getting you unduly worried about something that wasn't important, and that it could strain your trust in the bike and the people who sold it to you.

I suppose being new and under warranty, I could go for new wheels, but it's not worth the hassle to me. The cracks are hard to see unless you're up close, so I can live with them.

If you ever have doubts or are uncomfortable with your decision, search "crazing in anodized aluminum" or similar, and you'll find serious literature on the subject. As I posted, it's common and normal on rims because of the nature of the production process, and the flexing that rims get during production, wheel building and use.

For it to be caused by brake wear wouldn't it have to be on the brake track? The brake track is clearly indicated by the wear indicator groove.

Plus, the OP says, and the photo evidence of the brake track confirms that the rim is very new. Obviously brake track wear is not a factor, nor are caliper brakes implicated in any way.

But some people will seize on anything to advance an agenda. Got a rim issue? Get disc brakes. Girlfriend broke up with you?, must be hose lousy caliper brakes.