650B Elephant National Forest Explorer

Hey Ed, is 2.1" / 42c+guard generally the biggest you can go on a 45mm chainline chainset (presume you'll be running road running gear)? I'm guessing that'll be indentations on both inner (tyre) and outer (chainring) sides of the chainstay(s)?

2.1 is probably the biggest I can go (and the easiest size MTB tyres to obtain, hard to find a 1.9 one), it will fill in the clearance that a 60mm mudguard usually take.

The inside chainstay will have dimple, and possibly a dimple for the chainring.

It also mean you can get away with using normal road crankset, thought I will put a White Industries VBC (46/30) on it, or a Middleburn road 46/30 with external BB if I'm certain that external BB will last as long as square taper does, my experience said otherwise.