From the reviews-
"Was concerned about the size as it wasn't listed anywhere, but they fit great on my 7/8" bars (bar ends I ordered were 7/8" and fit well)."
They will fit the 636.
A few cruisers have 1 inch diameter grips for a fatter look, and most other motorcycles use 7/8 inch diameter grips.
"Until he reached thirty, Randy felt bad about the fact that he was not socially deft. Now he doesn't give a damn. Pretty soon he'll probably start being proud of it." from Neal Stephenson's Cryptonomicon novel (1999).