OK, I'm not sure how to explain this best... If you have a better wording in mind for the title, please edit or tell me:
The setup: I live in an apartment. The bathtub after the U-bend connects to pipe 50mm in diameter. That pipe then connects to a larger pipe (100 or 150, not sure) which then connects to the vertical sewer pipe. The 50mm pipe is straight and about 1m long - but it passes through a wall so I can't remove it. The bathtub connects to the 50mm pipe via a 45 degree junction and the 50mm also continues on in the other direction towards the kitchen.
So.... in Ascii art...
Neighbors above # Kitchen Bathtub # | | 1m Fat pipe # \-------------\--------------===============# 45° # # Neighbors below
The problem: I can clean the U-bend easily enough, but the straight 50mm pipe is another story. Over time it clogs and the bathtub starts draining slowly. With great difficulty I can get disassemble the connection to the kitchen and remove the 45° junction and poke around with a long stick which helps... for a while... but it's a pain to do so. I could however easily access the 45° junction and put a drain snake it (well, if I had one).
What fills me with doubt is that everything I read about drain snakes suggest that they are for removing acute blockage - something big suddenly stuck in the pipe. You can dislodge that and everything is fine. In my case however it's a slow buildup of gunk over years of time. The pipe doesn't block, it's more like it's inner diameter slowly shrinks... And I doubt if gettin a drain snake would help here. If there was something like a 50mm round brush, then maybe... but I can't find any.
Am I overthinking it and a drain snake is exactly the tool for the job, or is there something more specific for this scenario?