Bicycle riding the Elbe River from Dresden to Prague is a great way to travel. Flat ground, mostly dedicated and paved cycle routes for slow cycling (as in slow food).
Praha Bike rented the bikes, drove them to our pickup in Dresden, took all our heavy suitcases back with them, so it was a pannier-lite trip (the May weather cooperated as well... 85 degrees and sunny). Praha Bikes was great and the price was all-inclusive, so no surprises at the end. Two of our four of us purchased their own Bella Ciao bikes in Berlin (great bikes by the way) to fly home with them, and Praha Bikes kindly agreed to store these after the ride (Prague is a foot city, not bike friendly...too much traffic, no dedicated bike lanes, too many people, chunky cobblestones and compact enough to best be seen on foot), and they also offered to help them pack the bikes for the plane ride home... no extra charge. No guarantee that they will always offer this, but it was appreciated. Be sure to specify what you need and they will supply maps, recommended stopping, panniers, helmets, locks, etc.
If you have a choice, don't ride Dresden to Prague, the direction we went, ride the other way. When the wind blows, going Dresden to Prague, it's in your face. Not only does the river run the other way (the drop is insignificant for biking) but so does the wind. The first day, it was a bit of chore... after that the wind stopped so for us it was a non-issue.
Also, for the most part the Czech people on the road are more taciturn... reserved, not particularly animated or helpful. So if you start in Czech and go to Germany, each day gets better. By the time you get to Dresden, you have a most optimistic people who have done a most extraordinary turn-around since the wall fell. But this is a subtlety... either way is great.
We allowed 35-50k per day so that we would ride about 3-4 hours with long midday stops for glorious lunches, exploring every castle, museum, great view or whatever came our way. This is slow-cycling at its best. One of us wore a helmet, but the others preferred the European way of wind in the hair. Given the slow speeds, no cars for most of the ride, and flat ground, it's very safe and a pleasure to ride bikes the old fashioned way.
Our first night was in Bad Shandau, and in hindsight, I would recommend a shorter first day; spend the night in Pirna in Germany. Be sure to seek out Adoratio, the chocolate shop on the Main Square and buy more than you should. It lasted us the whole trip and was glorious.
As can be expected, Germany was more refined than Czech, although it was clear that Czech is upgrading the roads. Some were still gravel, but some showing gravel on the map had just been paved. If you keep an eye out for the little yellow Bike Route 2 signs, you will not get lost.
When you cross into Czech, the first big town is Usti. Do not stop, ride through and ignore it. It gives a horrible impression of the country, and one's immediate thought is that if this is Czech, skip the rest of the trip and take the train to Vienna. Don't give up hope, it gets much better. By Litomerice you fall in love with the architecture, the ancientness and the landscape.
Must do: Dessert (or a full meal) outside the Melnik castle overlooking where the Elbe and Vltava rivers join. The views are stunning, the service and setting is five star with 17th century elegance. We did not discover it until after we had a late lunch on the main plaza, but it definitely is a must-return.
The last full riding day, we ran into two German girls who were riding the full distance of Bike Route 2, all 500k of it. They had just come from Prague and said the first day riding out was difficult. Rough track. That night the weather changed, with a predicted drop from 88 degrees to 37 with cold rain, so we found the train station in Melnik and for the equivalent of a few dollars hopped a train that has racks for bikes and takes about a hour to do a day's ride into Prague. Thus, I cannot confirm what the first day's ride out of Prague is like.
Prague was of course eye-achingly beautiful, as the architecture is just street after street of drop-dead beautiful, but unfortunately, the locals have not yet understood the concept of care and feeding of the visitor industry. Unlike the river ride, in Prague we kept getting the feeling we were lunch... we were there to be fleeced by the locals. A high price for a cup of bad coffee, and then we see the locals getting great coffee.
This is typical of what happens when a country shifts from Communism to Capitalism, but it can be tiring. Having said that, there is a lot to do and English is spoken sufficiently that one need not learn Czech except for the basics to show one wishes to be polite. Of course, at Praha Bike their English was excellent.
We found a great place to stay however (Dům u velké boty (House at the Big Boot)), and the proprietor told us all the places the locals go where we would be treated right... he was right. Praha Bikes also offered to help us make those connections, so make friends and ask for help.
Bottom line: Praha Bikes is highly recommended, as is the Elbe ride.