I have a bunch of old Mavic tubular rims (GP4 I think) kicking around and got to thinking that maybe these could get built up as cross wheels. Wondering if the rim profile would work, and if they'd be light enough to make any sense.
Old GP4s (400gr) would definitly be a good rim choice for cyclocross tubulars. I would be hesitant to use the similar but lighter GL330 for cyclocross, probably not durable enough for offroad. Box section tubular rims should be a bit softer riding than aero V profile rims, good for cross. I think that any aerodynamic benefits of V profile rims at cyclocross speeds are really, really minimal and V section rims are generally heavier. The one benefit of V section rims however is that they can shed mud better than box section rims.