What arm lengths are offered?

170mm and 175mm.

What is the spindle width?

98.5mm, with zero preload.

Why do I need an Outboard Bearing Style bottom bracket for BB30, PF30 and T47?

eeWings are designed to be supported by bearing load at the ends of the spindle.

Can I use my eeWings Mountain crankset with my T47 Bottom Bracket?

Yes, but only with an outboard bearing style BB for a 30mm spindle.

What Bottom Bracket shells are eeWings Mountain compatible with?

BSA73mm Threaded Press Fit 92/89.5 Press Fit 30 (Outboard Bearing Style Only) BB30 (Outboard Bearing Style Only) 392 EVO The optimal Bottom Bracket to use with eeWings Mountain is the Hellbender Bottom Bracket. Hellbender Bottom Brackets are available in BSA Threaded, BB30, PF30, and PF41/92 options