Some front shocks says the travel can be changed 160mm to 140mm. So that is travel. Does it change the overall length of the shock or just the inside travel.
The height of the fork crown will increase the same amount as the fork travel - i.e if you are gong from 140 to 160mm then you will raise the front of the bike by 20mm - of course this also effects the overall geometry of the the bike itself, and the riding characteristics
I guess in theory you could build a 160mm travel fork, that bottoms out at 140mm, so the length of the fork doesnt change when you dial it down.
But! Why would you? One reason to drop to 140mm travel *and* reduce the fork length is to improve the geometry when climbing. A shorter fork when climbing is generally preferable.
Dont see it so much anymore.
I had a bomber, then a RS Psylo, both you could reduce by at least 20mm if i recall.