Riga Bike Tours offers 2 daily bicycle tours: at 12am and at 3pm, meeting at Ratslaukums and the cost was 10 Lats.  After meeting with Marcus (one of 2 guides), you walk a few minutes to a shop where they house the bikes.  The bikes are standard bikes and comfortable.

  Riga Bike Tours starting point

Meeting point for the tour 

Unlike a walking tour, the bike tour covered a great deal in 2.5 hours.  The tour goes through the Central Market area, the Russian district, various parks and came back into the city going through the Art Nuevo District.  The guide, Marcus, was very knowledgeable and informative.  A bike tour can cover several examples of an item (different Art Neuvo buildings) that happen to be somewhat apart (versus just confining to a small area in a walking tour).

The tour is a throwback to pre litigious time.  There are no helmets provided (didn't ask if they were available).  There weren't any forms to sign (to limit liability).  Just get on the bikes and take off.  The vast majority of the pathes were safe (bike paths, going through several parks, empty streets, etc.).  There was only one small part (3-5 minutes) of the path on a busy street and competed with cars. 

This is a "new" bike company.  Marcus mentioned about the other bike company and how they required a relatively high minimum # of participant to tour.  Not sure if the other bike company is still providing tours.

While always taking/enjoying walking tours (including the Free Riga tour), a bike tour gives you a chance to see more, especially areas off the beaten (tourist) path.