That depends on the airline. There are airlines that don’t have a limit on the number of baggage items and just a total weight limit (although this is rare). Here you could (in theory) check-in each pannier and bag as a separate item. I wouldn’t recommend this anyway though. Just because statistically the probability that 1 out of 5 items gets lost or is misrouted is much higher than for 1 out of 1. So in any case they way to go is to combine all your bags into to a single item.
How exactly, for me depends on the exact scenario:

1. I fly in and out but leave from a different airport than the one I arrived:
I usually use this: https://www.globetrotter.de/tatonka-packbeutel-schutzsack-einfach-transparent-1026738/?sku=5637203913
That is just a simple bag with a huge volume from a fairly sturdy fabric but still lightweight enough so that I can carry it along for the full trip. Some cycling fellows I know use bags like this as a protective layer under the tent (since they are carrying it anyway). It can accommodate all your bags even for a setup with 4 panniers, rack pack and handlebar roll. I used it even to carry the panniers and all the gear for me and my partner for a 6 week trip. So that we only had to check in one bag + the bikes and save some $$ that way. Be aware though that some airlines have limits on the dimensions of bags as well, so be careful to stay inside this range. Also consider that one pannier (or probably the saddle bag for the bikepacking hipsters) is your carry-on luggage.

2. I leave from the same airport I arrived
In this scenario I’d try to find a local where I can store my bags for both the bike and the baggage. My recommendation here is to have a look at the Warmshowers website and find someone who can store your stuff for a while (that is normally much easier compared to finding a place to stay the night). I once (I think it was Scotland) agreed with a Warmshowers member just to throw my stuff over the fence of their property (because they wouldn’t be there when I arrived) and collect it there two weeks later. Of course hotels also work, but some are not super happy if you just stay there for a single night and then ask to store two bike bags and a big duffel bag for two weeks. Anyways, did that at Hilton hotel once and worked 🙂
So if I have such an option, I use a different bag. It’s kind of a military duffel bag I obtained years ago at some sort of storage cleanout. It is just more rugged but obviously way heavier and I wouldn’t carry it all the way.

3. I only fly in
I would try to mail my bags home. Be aware though that Norway isn’t part of the European Customs Union (in case you live in the EU). So mailing stuff from there is more troublesome than e.g. from Sweden.

4. I only fly out
Easiest option is to go to a local sports retailer and buy the biggest duffel bag they have. Not the most budget friendly option obviously and also not super sustainable if you do this every trip. Anyways, if you have use for such a bag anyways, this is an option. Friend of mine did that when coming back from the North Cape (Hurtigruten boat to Tromsø, then go to the XXL store and buy a bag there, then go to the airport).
In my experience, airlines and airport stuff are pretty flexible when it comes to baggage items. Important is that they are really a single piece, nothing sticks out is attached or so, no straps etc. It doesn’t have to be an actual suitcase or bag. Some friends I traveled back from South America with, checked in all their panniers packed in a big banana box they got from a supermarket close to the airport. It was a bit annoying for them anyways though. They wrapped them with a lot of tape and then had to open it again because their air pump was identified as a “potential explosive” item.

Other tips when flying with bikes from my experience:
– Most important: Be there early. This cannot be said often enough. It is always different. How everything is exactly handled is a mixture of regulations of the airline, regulations and equipment of the airport and experience of the staff and for me, every time it was different at every airport. Many airports for example don’t have a large enough x-ray machine to put a bicycle through so they have to do a manual explosive test. Try to be at the front of the line when the check-in counter opens. If it opens late try to find someone else who can help you. It is almost certain that you have to bring your bicycle somewhere else (bulk baggage drop off). Automated processes (check in machines) basically never work with bicycles because of this and they have to go through a manual process. My rule of thumb is to add at least an hour to the time you’d be there normally if you don’t cycle there and have the bike already packed. If you cycle there and have to pack it add this time as well of course (and don’t underestimate it). If regulations are unclear and you might need to repack add more time.
– When it comes to “how to pack your bike” there are many different opinions. In the case of Norway it is worth mentioning that Norwegian (the airline) has pretty much the most relaxed packing requirements for bicycles anywhere in the world. In theory, you don’t have to pack it at all, just turn the handlebar and remove the pedals + release air. I would pack it anyway a bit in wrapping foil. My approach is to open the screws for the levers at the handlebar a bit, so they can wiggle, unscrew the rear derailleur and hang it a bit inwards with a zip tie and wrap it. I had the chance to observe how my bike was handled when leaving Stavanger airport last year. The treated it really nicely. Of course this is anecdotic evidence only 🙂
– When you fly with a real bike box or bike bag and you have to say the weight in the process, add a few kilos or even go to their max (if it is the same price anyway). That way you can also put some gear (at least things that are “bike related”) in the box.
– note down the serial number of your bike and/or take a photo from the place where it is engraved. In some countries you have to fill out a form where you put in the number. I once had to unpack my bike (Santiago de Chile) because of that and almost missed my connection flight because of this.
– Study the regulations of your airline carefully, print them out and take them with you in case of any discussions. Don’t rely on anything they say on the phone. I once had the experience (South America) where I flew with a budget airline locally. On their English website it said “we recommend to use a special bicycle bag”. The Spanish website (which I didn’t check) said “you must”. Didn’t pack my bike (only turned handlebar, removed pedals etc and some plastic foil). Staff said it can’t go like that. So I had 27 minutes to “craft” a bike box. So I looted some trash cans, begged some people for tape and finally succeeded. Didn’t carry any pulse watch there, but I guess my heart rate in this 27 minutes was much higher than on every mountain pass I cycled on this trip.
– Put airtags everywhere. Bike and bags so that you can trace your stuff if it gets lost.
– When you checked in your bags in some sort of makeshift “bag” or something similar to the sack I linked above it might be dropped of at the bulk luggage counter, even if you checked it in normally at the airport you left.
– In general the bulk luggage counter is the more important to observe. Sometimes airport staff just throws all the items on the floor from some trailer. If you are there when this is about to happen and you can identify your belongings you can tear it out of their hands and prevent that it gets buried under strollers, golf equipment, skis etc.
– Normally airlines require you to release the air from your tires. From a physics standpoint this doesn’t make much sense, since atmospheric pressure is only 1 bar. Meaning even in a full vacuum your tires wouldn’t explode if they can tolerate one additional bar to your normal riding pressure. Don’t start any discussions but do it your self. They will usually check this with their hands and release the air completely if there is still a high pressure on it. If you do it yourself you can leave some air in. They are usually happy if it “feels empty”. This is in particular important if you run tubeless to prevent any liquid from coming out.
– Pack your multitool with the bike, also your pedals and everything that you need to complete it. That way you can still assemble your bike if your checked baggage does not arrive but the bike does. Obviously don’t pack it with the carry on luggage since it might be declared a “weapon”.
– In general try to pack essential stuff in the carry-on luggage so that you can have at least some fun in case your checked baggage does not arrive. Like doing a local circle around the airport town where you wouldn’t need e.g. sleeping bag and tent.
– Protecting your bike is obviously much more important when flying to your destination than when flying back and you have plenty of time to repair any damages. Also depends a bit on your plans though. In Oslo you have a nice bike shop (paajuhl or something like that, matthew has a video) that can help you
– Everything you read on the internet on this topic (especially regulations) might be outdated pretty fast (that’s of course also true for this text)

I realize I’ve written a long text (I am in a train currently) hope all of this doesn’t discourage you. Let me say that in the maybe 20 to 30 flights I took with a bike, never something really went wrong in the sense that I couldn’t fly, lost anything, or was without my gear. Some preparation is key there though and I heard many stories.

Finally I have to say that arriving in Norway by ferry is much nicer and hassle free. One of the reasons I’ve chosen Norway or Scandinavia now as my go-to location multiple times in row. Actually I try to avoid flying with the bike these days for several reasons. I know of course not everyone has the option.

Awesome to hear Julia! Tromsø Outdoors will fix you with two bike boxes. And happy to hear your bikes arrived on time and in perfect condition! Have a great time in Norway! The weather in the south is fantastic right now!

Bike Box Travel