bicycling Bacharach to Braubach

" Does anyone know whether there is a dedicated bicycle path on both sides of the river for these locations? "

There is on both sides, and it's almost completely flat.

I found this web site informative in planning bike tours in Germany:
http://www.bicyclegermany.com/rhine.html

Mile 21.2 (34.1 km): This is Bacharach and it is guarded by Burg Stahleck. The Burg, or castle, also serves as a youth hostel or Jugendherberge. (On my Links page, you can find a link to the German youth hostels.) In Bacharach we take shelter from another shower. But this time, we sit under an umbrella in a Biergarten and do what one is suppose to do in a Biergarten. (Grow beer from a seed? Nope! Try again.)

I seem to remember someone writing in about a bike path on the right bank of the Rhein in this area, but it cuts across the Filsen peninsula. I'm not sure if it comes down to the river before it gets to the ferry landing across from Boppard. I see from the Google view that there seems to be a path of some sort along the river side of the highway. In 2004, I came across the river on the ferry from Boppard and walked along the highway to the train station in Filsen. It seems to me that I walked on the shoulder of the highway; I don't remember walking on a separate path, but there wasn't that much traffic on the highway.

I did the exact trip last summer and it is super easy. There is a dedicated bike path that is well marked, almost always close to the river And yes it is on both sides of the river. The only minor issue was finding our way up to Marksburg Castle, the road is all the way around the hill from Braubach, so we just took a foot path instead and parked our bikes. The road is kinda steep anyway.

Thank you for your replies. We are looking forward to the trip. Would you recommend bicycling back or taking some combination of trains? Thanks!

Since you are following the river on it's course down stream, you are going gently downhill almost all the time. As i remember there were some stretches where you could go quite fast. This in turns mean that the trip back would be gently uphill all the time, wich i would find very annoying, so maybe the train would be the best option on the way back. I did it as part of a bicycle trip from Frankfurt to Cologne, so i have little idea about which train to take.

The difference in elevation between the towns is only 17 feet.

You're right Stephen, the 5 meters diference in elevation is not that much, Our trip that day was from Bingen to Koblenz, where the difference in elevation is 25m. It's not exactly the Tour de France, it's more about the feeling of going gently donwhill all the time, going the other way would annoy me a lot. I'ts propably also a mental thing.

When you say "ride our bikes", are you planning on bringing road bikes with narrow high pressure tires (e.g. 700x23s)? My limited experience in riding in the North Rhine-Westphalia and Mecklenburg regions of Germany found riding surfaces extremely variable in going point to point. Fortunately we rode rentals with tires suitable to the surfaces.

This characterization is pretty accurate in what we experienced:
http://www.bicyclegermany.com/what_to_expect.html

On a typical tour we ride most of the time on asphalt (tarmac for you
United Kingdom folks). However, during a typical day, a rider may
encounter many different surfaces including pavement, gravel,
cobblestone, and even dirt footpaths. Until I discovered deep sand, I
used to think that cobblestone was the worst of all road conditions.
Cobblestone roads are dangerously slippery when they are wet. Narrow
tires (1 1/4 inch or narrower) make all but the best paved surfaces
more dangerous. Check the special page of path conditions that shows
photographs of different path conditions we have encountered.

And almost as bad as the cobblestones:

Plattenweg (a path made from Platten) is another instance of using
less than ideal material for a bicycle path. OK, I understand that
these paths were originally built for farm equipment or military
vehicles and was not built for bicycles. However, they are not
uncommon in the former East Germany. A "Platten" is a concrete plate
with two or four indentations for handles. They vary in size but
typically are about 3 feet wide and 6 feet long. To build a road, they
are laid side by side, 3 foot section after 3 foot section, until the
road is finished. Each joint is designed to loosen a filling in your
teeth and there are joints every 3 feet, don'tchaknow (this is a term
I picked up living in Montana). See the picture on the right show a
path of double Platten. The Plattenweg shown on the left is of a
different design and is becoming slowly buried. Good! The dirt path
along side is smoother than the cement Platten.

http://www.bicyclegermany.com/path_conditions.html

Having tires with air volume helps smooth out rough surfaces and float soft ones.