This photograph shows a tank DT-29 machinegun, mounted on a motorcycle. Photographs of motorcycles with infantry DP-27 machineguns are very common, as that machinegun was eventually adopted for this purpose. However, that was not due to the superiority of said gun, but due to a requirement for parts commonality with infantry.
The DT-29 was, in fact, superior to the DP-27 for this task. 63 rounds in a compact disk magazine (compare with 47 rounds in the DP's massive flat disk), and a much better mount. While the DP just had its bipod resting on the sidecar front, the DT-29 had an adjustable mount, resulting in better ergonomics for gunners of all heights. Another benefit of the mount was that it could be easily extended for the purpose of anti-aircraft fire. On a motorcycle equipped with the DP-27, the gunner had to dismount and fire from a crouched position next to the motorcycle if he wanted to achieve very large gun elevation angles.