Hello all, I'm hoping that someone could help me out with some beginner's questions.

I have a Giant Anyroad 1 which has disc brakes. I'm interested in buying a better set of wheels that I can quickly put on for group rides and tri races and keep the stock set for more leisurely rides. But what exactly would I need to buy in order to have two sets that can easily and quickly be swapped?

Wheels, inner tubes and tyres obviously.

Hubs - Do they usually come with the wheels?

Disc brakes - would they come with the wheels? Is it easy to make sure a new set would fit into the existing brakes?

Rear gear cassette - should I buy a second one or is it possible to swap my existing one over?

And finally, do you think it is worth it? With the stock wheels I can average 30kmph over 50k or so. Would there be a clear different on better wheels?

Many thanks
Duraz

In bicycle terms "wheels" mean hubs, spokes, nipples and rim.
For new, shop-bought stuff:
Quick releases or thru-axles may or may not be included. Rim strip may or may not be included.
Brake rotors, cassette, tubes and tires are "never" included.

It would be nice and yes, worthwhile, to be able to swap wheels between fatter/more knobby to lighter/faster rolling.

Rotors will not likely come with the wheels, so you'll need to buy: a wheelset, disc rotors, a cassette, tubes, tires. edit: and as dabac mentions, rim tape may or may not be installed on the wheelset

Things to pay attention to:

• Rotor and rotor mounting: you need to mount the rotors to the hub, two major ways to do so in 6-bolt and CenterLock/AFS; make sure you match the rotors to the type of connection on the your hub of your wheelset (note: if you have CL/AFS hubs, you can get an adapter to use 6-bolt rotors, but you can not adapt from 6-bolt hubs to CL/AFS rotors)
• Rotor size: match the sizes on your stock wheels, front and back
• Axle: match the dropouts (how your wheels fasten to your frame) on your bike. They'll either be Quick Release (QR) or some type of Through Axle (TA, most likely 12mm). Some wheelsets allow you to easily change between QR and TA, but make sure you're covered before you buy.
• Cassette: you may want different gearing if you're going to be riding different terrain. I wouldn't want to swap cassettes because it would kill a lot of the convenience

I recently did this, keeping my cyclocross tires on my stock wheels, and putting my road tires on my newer wheels. (My bike has rim brakes, though).

Wheelsets generally come with hubs, spokes, rims, and usually skewers (or through-Axel's?)...they will NOT come with a cassette, or disk brakes. To minimize setup changes, you'll want similar disks on each set, and a similar, but not necessarily identical, cassette.

I purchased a second cassette for the new wheels, and am VERY happy with the results. I can easily switch Wheeler's for on or off-road, with no tools, no tire changes. The rims are close enough in width that I don't change the brake setup at all (disks might be more finicky between different wheels, which is why you'll want to try to duplicate things as closely as possible).

The 2 cassettes are 11-28 & 12-27, but both work without derraileur adjusting...maybe a small tweak on the barrel adjuster if I want the BEST shifting, but it's not a necessity.

Definitely get a second cassette, if you're going to use 2 Wheelsets and tire setups anyway. No reason not to.

Regarding if it's worth it, I'll add, that, for my "better wheels (fulcrum Racing 7 LG CX)...I lost about half a lb off the cheap stick wheels, which was not very noticeable in riding...what was noticeable was the better stiffness. Power transfer from pedals to road feels more immediate. Could be stiffer spokes or better build, but I think I can tell. I suppose weight could also play a part in that.

Is it worth it? For me the main goal was 2 tire options...but I decided to go a step up in wheel quality too, and I'm glad I did. Just feels nicer.

Excellent, thanks very much for the advice guys. Seems as though it is a bit more technical than I had realised but could be an interesting first upgrade project for me!

It sounds like a lot, but it's really not terribly complicated. It's just that the standards, w/r/t discs on road bikes, aren't set in stone just yet, so you just need to double-check that all of the parts work with all of the other parts.

Ditto...the cassette should be easy, either for you with a cassette tool, or a 5-minute job for the bike shop.

Making sure you rotors on both wheels are the same will take some more research and figuring out.