Originally Posted by cyclintom
Finish of the bikes is about the same. The lugwork on most Mercians isn't as fancy as the Rivendells but the Mercian Vincitore has fancy lugwork of very high character.
I WOULD NOT recommend 650B wheel bikes for touring because you simply can't get tires anywhere but from a few sources. Now you could probably carry one spare and count on overnight delivery if you used that tire up. Rivendell sells these tires and stocks them and is exceptionally cooperative with tourists.
I wasn't thinking of the avaibility of the 650b tyres, just their utility, but its a good point that they would be
hard to find compared to 26" or 700c. The lugwork complexity does depend on the particular frames you're comparing, the Quickbeam has quite simple lugs, I think what might be more of a difference is the lug lining that Mercian does. I know some people who love it and others that hate it, I'm in the hate camp, just an aethsetic thing and I know its an option.
I think the real differences between Mercian and Rivendell are the tyre clearances, Rivendell's love of the 650b tyre size for some of its bikes and Rivendell's standard headtube extension and small up slope on the top tube.
I know that you could certainly ask mercian to build a bike with an upslope and headtube extension, I just don't think their default style would be as comfortable as that of Rivendell.
Mercian are definitely the best deal on a custom frame out there though.