To cycle in Karlsruhe is pretty nice, no hills, everything is flat. That's different in Saarbruecken. The university is approximately 5km away from the city and there are several hills on the way (while the way back to the university is worse than the other way).
Today I cylced twice (!!!) to the city to visit two shared flats. Each way in less than 20mins, not bad, not bad. Both flats were nice, I hope to get one of them...