2012 Concours is shaft but the other 1700's are belt.
Can anyone tell me what the thinking is on final drive? Pros and cons?
It's two things, really: Cost and "authenticity"
The cost factor is probably the most important. Back in the 80's when all the Japanese companies were fighting for market share, they loaded up their bikes with lots of "extras" to try and beat the competition. That's why bikes back then had full instruments (including in some cases, gear indicators), center stands, shaft drive, cast wheels, low- or no-maintenance valves, etc.
But then the market crashed and they were put in a position of trying to stay afloat amidst sinking sales, so they started cutting corners wherever they could. Chain drive is cheaper and easier to make than shaft, so a lot of the new bikes went back to chains, even in some cases where the previous models had shafts (Honda Magna, for example.) We also saw the disappearance of center stands and (at least on the cruiser bikes) full instruments - a lot of the modern cruisers have a speedo only, no tach, fuel gauge or other instruments.
The other factor is "authenticity." In the Cruiser market, "Authentic" can be translated to "Looks like a Harley." Since Harleys have belt drive, the big metric cruisers have been going to belts, too.
A final point on the cost issue: If you think about it, the manufacturer only makes money when the bike is sold new. They get squat from the second and subsequent buyers. So, if they make a motorcycle with features that will last 50,000 miles, and the first buyer is only going to keep it for 10,000, then all the money the manufacturer put into making it a 50,000 mile bike was wasted.
Shaft drives are low maintenance and can go long distances without any replacing or even fiddling with (which is why Gold Wings and BMWs have them.) Chains and belts do occasionally need to be replaced, but here's the kicker: I don't know about belts, but you can generally get 20,000+ miles on a chain (except maybe for a hot sportbike - not sure how long those last.) So, going back to what I said above, if the first buyer isn't going to wear out the chain or belt (and if it's a cruiser, chances are he's not), then why should the manufacturer waste money on a shaft?
They aren't going to derive any advantage over chain/belt driven bikes because by the time that chain or belt wears out, the bike will be on its second owner, that is, the person that the manufacturer didn't get one thin dime from.
Edited by martinjmpr at 3/27/2012 7:46:53 AM