Citybike Wien

Since the weather was nice when i left home for work today, i decided that instead of taking the U6, i would use a Citybike for the first time. They have been around for some time, but I was always too lazy or too much in a hurry to register.
I managed to persuade the Terminal at Alserstrasse, that i need a bike, the bike was usable, and I drove to Schottenring to enter U4. So if it does not rain, i should do this more often, because it does not cost extra time compared to the subway, which goes quite an indirection.
On the Website i can log in and check from where to where i drove in what time (15minutes today). Now it would be nice, if there would be a Terminal near “Wien Mitte”, where i could catch the S7. Until now my only choices are Stubentor (continue via U3 to Wien Mitte) or Schwedenplatz (continue via U4).
For my way back home a terminal near Handelskai would be nice, but I guess that won’t happen in the near future.