Owing to general laziness since a mixed surface trip, my Thorn is currently sporting : 2.3″ Marathon XRs, 3 bottle cages, front and rear racks and my usual bodged Crudcatcher front/rear combo. This is in addition to about 3″ of stem stackers, and gearing giving me a max on the flat speed of about 25mph @90RPM.
I carry about 5 Kgs of stuff 8 miles each way in the sun using a single front pannier on the rear rack and all my remaining water bottles are so crap I don’t use them.
In my mechanicing days I once saw a guy using a 24″ wheel DH rig of some sort with 3″ slicks and tripleclamps to do a couple of miles around London each day… To be fair, hucking whole flights of steps must be useful!
EDIT: ^^^yeah that looks about right!