Cycling training - 220km in 4 weeks I have 4-5 weeks to prepare myself for a one day, 220km ride on a road bike, flat terrain (Germany, Ruhr Valley). This year my max is 70km (I could ride 100km, I'm doing bike rides since 2 weeks ago, have done only 3). I'm training since 5 weeks.

Weekly:
- gym strength training 3x a week
- 2x a week interval trainings (spinning, swimming, etc)
- 1x a week long bike ride

The plan is to increase that long bike ride each week by some serious amount, hoping that the gym and interval trainings will help me achieve the goal.

Is this achievable?
I would say that you should definitely work more on long bike rides and less on strength training. You can always wimp out on the hills and put it in an easy gear.  If the max you have done is 70km, then you really need to work on the distance part of it.

Another important thing to train for is how to fuel yourself during the ride.  Most moderately fit people could probably do 70 km without worrying about how to properly hydrate and eat during the ride. But when you get up around 200 km, you really have to think about how to eat and drink in the correct amounts so that you don't "bonk" when you are out on the road.