see also cycling
The Elbe-Radweg (Elbe cycle route) runs mostly alongside the Elbe-river through the Czech republic, Saxony, Brandenburg, Saxony Anhalt, Schleswig Holstein, Niedersachsen and Hamburg. Due to its close alignment with the river it does not have many steep slopes, making it popular with novice as well as experienced cyclists earning it the German cyclist associations (ADFC) approval as Germany's most popular long distance cycle route for a tenth time in a row in 2014
Although Germany is maybe not as cycle-friendly as the Netherlands or Denmark, it still has excellent resources for cycle-tourism, that not many countries offer. There are several "bike friendly" hotels and hostels along the route with various price ranges. Finding accommodation - even on short notice - should not be a problem in the major cities along the route. However plan your route beforehand to be able to see where you will likely stay and whether or not bringing a tent with you is an option. The German cyclists association ADFC promotes and encourages cycle-tourism and has excellent resources for maps and accommodation catered to cyclists. Members also get discounts at some associated businesses (not unlike the AAA discounts you get in the USA for motorists) usually in the 5%-15% range.
Keep in mind that it will rain at some point of your trip and - if you are unlucky - maybe for days on end. Bring clothes that keep you warm and dry and protect your bags against the rain as well.
The most popular entry points in Germany are Dresden and Hamburg that both have international airports, although Hamburg (HAM IATA) serves more destinations than Dresden (DRS IATA). Both Dresden and Hamburg as well as many towns along the route have regular fast and reliable train connections and Hamburg is one of Germany's major ICE hubs. Bear in mind however, that a bicycle cannot be taken on an ICE unless it is folded or packed as normal luggage. There is no such limitation on IC and regional trains.
If you want to learn only one language before heading out, make it German as it is the second most common foreign language in the Czech republic after English, whereas Czech is next to useless after you leave the immediate border area. Proficiency in English rises along the route as you go northwest, but the city-countryside difference is more notable than any geographic division. Older people in the east, that went to school during GDR times (1949-1989) might still speak some high-school Russian, but don't count on it. Other languages that might be spoken by college educated people are (in decreasing order of likeliness) French, Spanish, Italian and (in the North close to Hamburg and Cuxhaven) Nordic languages such as Danish or Dutch.
in addition to the listings in the individual city articles the ADFC offers great resources for bike-friendly accommodation that cooperate with them under their (English language) "Bett und Bike" website While taking a tent is a great idea in theory, you should observe the German laws regarding camping.
From Špindlerův Mlýn (Czech Republic) to Bad Schandau
From Bad Schandau to Dresden
From Dresden to Magdeburg
From Magdeburg to Hamburg
From Hamburg to Cuxhaven
As everywhere commonsense should reduce all kinds of risks significantly. In general terms all cities along this route are safe, with Germany being (slightly) safer than the Czech Republic and Western Germany being (slightly) safer than Eastern Germany. Violent crime is extremely rare, but bicycle and baggage theft do occur, so keep an eye out on your belongings at all times. During flooding events (e.g. the major floods of 2002 and 2013) parts of the route or its entire length may be closed for traffic and/or generally inaccessible. German authorities tend to err on the side of caution, so that if you are allowed to go, risks are usually negligible. However the weather can change within hours, so paying attention to the weather service and special warnings is certainly advised. Not least to avoid being caught in the rain when you can or want to avoid it.
As the vast majority of travellers that do this route only one way, do so downriver, you are likely to be in either Hamburg or Cuxhaven from there you can go on to:
Should you decide to go upstream your destination will be most likely Dresden or Saxonian Switzerland see the go next sections of those articles for more information