You mean the B2, I assume? You can also take the Route east of the B2 (Zahne, Malterhausen, Bardewitz, Zülichendorf, Dobbrikow, Zauchwitz. Stücken, Tremsdorf, Saarmund, Güterfelde and so on). It is 10% shorter than the R1 Route.
I know the Route from Berlin to Zülichendorf quite well, to Zauchwitz I rode almost every week with the road bike. This is are very low traffic route. No cycle path mostly, but I consider it an advantage. YMMV.