165mm, external BB (68mm British shell)
Since you asked for 165 and then got excited by 155, I feel moved to draw attention to the (theoretical) availability of 160mm FC-R7000 (Shimano 105) cranks, if not for your benefit then for that of strangers from the future.
Since you asked for 165...
I could have specified "165 maximum", but given what I knew at the time, it seemed unnecessary.
Nonetheless, I and the friends we haven't met yet, are grateful to have had our attention drawn to the possibility of a third way.
@Scilly.Suffolk started
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Since you asked for 165 and then got excited by 155, I feel moved to draw attention to the (theoretical) availability of 160mm FC-R7000 (Shimano 105) cranks, if not for your benefit then for that of strangers from the future.