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.
"He had never counted on anything except surprise and unpredictability and danger" from Lee Child's Bad Luck and Trouble novel (2007)---------------
"There's always the chance I'll screw up. That's what keeps it from getting boring."
from Dean Koontz's The Eyes of Darkness novel (1981)