We got hella river valleys around here! I grew up around Ellicott City and there are some mean hills down around Old EC (check out River Rd/Ilchester Rd/College Ave). That area ties into some two-lane country roads extending out into western Howard County (Triadelphia area) that my distance cycling buddies train on. You can kind of noodle around in and out of the Patapsco River valley to put on elevation. There are similar situations around rivers/reservoirs like Prettyboy or Loch Raven. All of this is about a half-hour drive outside the city.