They do get quite a bit tighter as the suspension compresses and the swingarm moves more into line with the gearbox sprocket and the suspension gets toward the centre of its travel. Mine is similar, 50/55mm slack on the stand, but probably nearer 25mm with the bike supporting its own weight and about 15mm with me sat on it. It does depend on what preload/sag you've got it dialled in; and if you've got an long-in-the-tooth OE shock, then it'll tend to tighten up even more!

Whenever I adjust the chain, I always check it again with me (or the Mrs) sat on it to check its not over tight in the middle of the suspension's travel. When I load up with luggage I always do a precautionary check before riding, and quite often I've found the need to loosen the chain back off a bit. I guess you could even ratchet the bike down and compress the suspension fully and check...

It isn't an exact science though, trial and error and plenty of checks at different levels of compression. All bike's with long travel suspension are a bit hit and miss with chain adjustment, it isn't just the Tenere, although some do benefit from having the swingarm pivot in closer proximity to the gearbox sprocket which helps.

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