If you want to buy motorcycle gear in Berlin, you can find it in those stores. You can also buy it on fc-moto.de, the largest online motorcycle store in Europe.
Online options
If you know what you want, buy online from FC-Moto. It has more choice than any store in Berlin.
For plastic parts like hand protectors, handlebar weights, grips etc, but from AliExpress. It’s much cheaper. My hand protectors cost half as much as SW-Motech ones, and they were identical.