They do not break very strongly, but fine for city use for me. And i really like the fact that they are careless, same like using a belt and no grease.
Also I am using this bicycle on a fixed gear hub so breaking power does not need to be too strong.
But yes they are heavy, but this bicycle is heavy. This is a very old design, when frames were not welded. Riding a Strida in comparison is like being in the future…