| Yep...it will shorten the wheel base...the 748/9** series do have eccentric adjusters.
In effect, the chain is tightened by doing just that...pushing the back wheel further away from the sprocket, and therefore the front wheel. Taking it to the extreme, if you want an even longer wheel base, you have to fit a mag swingarm and an even longer chain depending on the gearing.
However, most people new to Ducati ownership don't realise that in adjusting the chain it has a direct effect on the ride height, even if its adjusted only a little.
When I first fitted a new chain to mine...i also changed the steering head angle to the steep setting. The chain that I fitted was a little short, and that, combined with the shorter wheel base and increased ride height made for a very entertaining ride!!! Its worth getting the correct length chain for your gearing...the tranformation in the handling is quite noticable when the hub is posiioned correctly, and the ride height adjusted to suit.
Search Shazzams posts. He has covered the chain length/gear ratios/hub position many times before and posted a great chart covering all combinations some time ago.  | 
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