If my bike is limited primarily by the brake bridge height at ~25c for a 700c wheel, would I be right in thinking that would be an equivalent radius as 44c on a 650b rim?
From Sheldon Brown; (622 mm [700c] + (25*2) -584 mm [650b] ) / 2 = 44
To a first order approximation. There's a bit more to it than that, so don't commit to 44-584 if 25-622 is within 1mm of interference. You really need to account for rim width and tread band thickness to get a proper estimate.
If my bike is limited primarily by the brake bridge height at ~25c for a 700c wheel, would I be right in thinking that would be an equivalent radius as 44c on a 650b rim?
From Sheldon Brown; (622 mm [700c] + (25*2) -584 mm [650b] ) / 2 = 44