My reply is similar to another post I just made to your question in http://forum.xda-developers.com/show...php?p=51184760
thread. This bike mount in your link above doesn't look as universal to fit your phone with any case on it. Sorry, I can't read German, so not sure if that case if form fitted for a naked S4 mini which obviously wouldn't be a good idea either.
In my opinion, when it comes to smartphone bike mounts, you want to be sure they have universal fit and can accept your phone with a rugged case. Imagine going downhill and falling down. Beside the point you need a protections
you phone will need an extra protection too, not just relying on bike mount itself. That's why those Arkon SMWPCS534 and SMWPCS532 mounts in the link I provide above look like they will do a job!
If you find my post helpful, please hit Thanks
Complete list of all smartphone and tablet accessory REVIEWS by Vectron -> HERE