But you would recommend going by the national train services? So ICE (in Germany) and the train in Czech since I am a junior?
You'll have to do the comparison yourself. A pass will give more flexibility but when you book in advance, fares can be lower. Interrail has reduced prices for juniors.
If you're taking a bike with you, take into account that not all ICEs can take a bike and a reservation must be made for taking a bike in German long distance trans (not sure about Czechia).
I would recommend to check out special offers on German railways and Czech railways website… there might be cheaper offers than by Interrail Global pass.
Traveling inside CZ is super cheap.
Oke so:
If I want to go to Czech by Interrail I will have to buy a global pass for at least 4 days. I can use this for going to Czech (day 1) and for example go to Berlin (day 2), another city (day 3) and going back to Keulen (day 4).
But you would recommend going by the national train services? So ICE (in Germany) and the train in Czech since I am a junior?
The one country pass is only valid in the one country you choose. You would need a global pass if you want to start outside of Czechia.
Validity of one month means e.g. from 16 July until 15 August.
But the best is to make a plan with your journeys and then check the normal prices and compare them with a pass price. If you can book in advance, then fares to Czechia can be quite low, e.g. via DB or Czech railways. Domestic fares in Czechia are quite low anyway by west-European standards.
Das vlot-was daar nog vorige week.
1 country means what it says- ONE country, not 2. There is NO ´free´ trip to it included!! otherwise anyone would buy for GReece and go there for just 30-40€ all across EURope
For CZ a 1country is a bad idea-certainly if you are junior+student (with ISIC) or senior>65. You get 50% discount on all local tickets and these are even at full fare cheap enough. Fiets=jizdny kol-on many weekends there are special touristy trains from Praha (od Prahy) to bikeable areas-CZ is rather very hilly and cycling is not everywhere a pleasure.
CZ has at least some 1000 stations-many are tiny stops-just a few stones beside the rails. Big city Praha has at least 20+ different nadrazi=station.
For Deutschland-only for transit-and taking the route via B-DD (=Berlin-Dresden) just buy normal tickets via bahn.de AND DO-repeat DO also reserve for the bike-it cannot be taken on the ICE (most), so that again means the direct train Ams-Ber and change to ditto direct B->Dresden-Usti-Praha. The route you mention is very rounadabout and not direct.
IF IF you really want to save and take the trouble to only use the local/Nahverkehr trains (Many more changes, takes much longer, probably enormously overcrowded) there will most likely be a 9€ MONTH ticket for all of DE (incl bustram)-so you can even use it for return in same month.
Noone will come after you if you would only use 2 of the 3 days-or you could use it for a daytrip by train to a further place in CZ -or in DCE to visit later on a day off some place-just pay till border NL/DE-but with 1 country you have to do that anyway