John N - Another thought with mixing and matching wheel sets -

I have on my radar a Surly ECR. The reason for the thought of it initially was what I described with the soft trail conditions in my previous reply. You can get up around a 3" tire width on the ECR. They have 2 versions of the frameset made to different wheel options (I forget what those are, I want to say one was 27" and the other 29er or 29+? I'd have to look it up again). What I have been thinking of is setting the bike up with more wheel set options so I can have a wide floater wheel set for the soft conditions then have others down to maybe 40-50mm width.

What I found was with disk brake framesets (which that is all the ECR comes as) you CAN do this, however the variance of the rolling OD of the tires needs to be taken in to consideration. With smaller diameters pedal strike in turns can be a real issue. Even 1/2-3/4" reduction in radius (1-1.5" diameter) can be enough to cause issues - it brings the pedals that much closer to the ground when banking turns.