Originally Posted by
sreten
Hi,
9 speed will always be under pressure as the first rear size than cannot use a generic 5 to 8 speed chain, but it will always work with a 10 speed crank and 10 speed chain.
So long term expect 10 speed chains and cranks to predominate over 9 speed in terms of the choices available
This is a really good point. Although a 9-speed chain would still work on 8-speed (it just wouldn't shift as well on HG ramps/gates, the same way that a narrower 10-speed chain wouldn't shift well on 9-speed stuff).
Older chains designed when 5- and 6-speed drivetrains were new, were wider than current "8-and-below" chains.
But I think the way things have shaken out, with 7/8-speed HG and lower (non-HG) stuff all using the same chain, and 9/10/11 each requiring successively narrower chains to shift as designed, the higher-geared stuff lacks the same sweet spot as 8-speed stuff. Maybe 10-speed stuff will start to go obsolete 5 years from now, as 11 predominates. But 8-speed will probably remain on lower-end bikes, and thus remain in currently-manufactured supply.