Predecessor of SI encapsulated by metres and things like that (6)
I believe the answer is:
metric
I'm afraid I can't explain this answer.
Can you help me to learn more?
(Other definitions for metric that I've seen before include "Successor to imperial (system)" , "Like some feet" , "System using litre and gram as units" , "Relating to poetic rhythm" , "Like decimal measuring system" .)