Originally Posted by
Slaninar
Most roadies I know recommended 105 and 10 speed because it is "future proof" - like you said - parts availability etc.
Nothing is future proof, and parts availability, even for cassettes for 7 & 8 speed gets worse every year. I used 8 speed for MTB's but as soon as the XT level was discontinued, made the switch to 9 speed, we are well past that for road bikes, with Shimano only offering HG-41/HG-50 level cassttes, which are effectively Sora. Can't see these disappearing for many years, but at the same time, you only have one option. For 10 speed, that's effectively obsolete at the higher (from 105) level up now with the introduction of 5800 11 speed.