What's this on the Hyperstrada? *Picture*

I believe it to be a pressure canister associated with the remote preload adjustment on the rear shock. There is a small valve (a la tyre air valve) in the center of the canister for re-gassing. The dealer tells me the owner needs to do nothing with it. Happy to be corrected if I have got this wrong.

Bingo. Don't mess with tire valve. Rear adjustment is at base of spring (flat head screw) and spring loaded knob with detents under left knee.

If it was Motard SP, it has better suspension all around and different preload can location.

Pressure canister is rite I'm told on most bikes that little canister holds over 1200psi, someone can correct me if I'm wrong, I'm not going to mess around with it to find out.

It tends to piggy-back parallel to strut on the nicer Duc suspensions.

That is a remote reservoir for the shock fluid. There is a piston inside that separates the fluid from the high pressure gas (usually nitrogen). This stabilizes the shock action as it heats and cools, note that the exhausts are pretty close to the shock body. Simple shocks tend to be emulsion type, where there is no separator.

The cylinder that pushes fluid into the preload adjuster is under the black knob. I don't have much to complain about the Sachs shock, we'll see how it feels after I get my forks back. But I can order an Ohlins that offers the same, plus compression adjustment. When it comes to suspension parts, you generally get what you pay for. Ohlins is the gold standard of the industry, with Showa close behind.

PS I don't have the parts list handy, but I suspect that the regular Hypermotard uses the same shock - maybe without hydraulic preload.

Okay, I tried to DL the parts list from the DNA site... and it gave me the Owner's Manual. But the gallery of the 'Motard does not show that remote reservoir...another reason to go for the 'Strada instead.

Don't you love it when your decisions are vindicated?