Biking tour of Wachau valley (Austria)

Which town in the Wachau Valley do you dock at? I'm thinking maybe Krems? Just google 'bike tours in xxxx' (whatever town you'll be in). You should find what you need.

Check here: https://www.nextbike.at/en/niederoesterreich/

You really don't need a tour. Just rent some bikes from Netbike as mentioned above and bike on the path along the river which passes Stein, Duernstein, Weissenkirchen, Spitz and Melk. You could also cycle the opposite side of the river which includes equally beautiful sites, like Burgruine Aggstein, but less villages.

Most of the biking tours I am aware of start in Vienna any way.

If you decide to bike on both sides of the Danube river consider that there are no bridges along the Wachau valley, only on either end, i.e. Melk and Krems, about 20 miles apart. Inbetween there are two ferries though, in Spitz and Dürnstein.

It is interesting to use these ferries as they have no engines. They move just due to the drag of the water flow.

Dear OP

Where are you stopping? If Krems then a bike ride seems like the call. Not at all a bad town, but the bike ride to and from it is sublime. Easy ride up stream on the Krems side of the Danube for 10 miles and back.

But if Melk be aware that to get into the Wachau valley you'll climb a bit. And if you want the north bank (which most do) you'll cross a safe but large and somewhat time consuming freeway bridge. If you were going to ride 15 miles on the north side of the Danube into the Wachau from Melk, 2/3s of it would be a steep hill and big highway bridge coming and going.

Plus you'd miss the Melk Abbey, certainly one of the greatest Baroque sites on the planet, probably the most mind-blowing "church" on most Danube cruises.