Larger diameter = larger polar moment of inertia
Hollow = less weight (go faster!)
If I did the numbers right, a 24mm hollow bar would have to have a 9.5mm (~3/8") wall thickness in order to have the same torsional rigidity as a 22mm solid bar, assuming the same material (i.e. shear modulus) in both bars. But, with the hollow bar, you'd save about 2 lbs. for every foot of bar length (if it's made of say, steel). Assuming the bar is say 4 ft long, that's 8lbs. of weight savings using the hollow bar. Hey, every bit counts!
But come on, we all know we'd be better off w/ an extra long hot dog with a few hose clamps and some bolts. I'm in!
BTW - any of you have material prop's for a Ballpark frank?
