i have a 113mm bb spindle and am getting a crankset that recommends a 116mm spindle (shimano 600ex arabesque). can i use this spindle or should i try to find a 116mm? Rivendell sells a 115mm for $12. How about that? Or is there really a big difference in a couple mms? what would be the downside? Would the crankset touch the bb? thanks!

I too am curious about this, the only thing I can think of is the chain rings are farther back and may hit the chain stay if using the shorter BB, on a geared bike I dont think 3 mm would be that far out on the chain line?

slide the arms on the BB and see, should be several MM (5~+) of clearance between the frame and the inner chainring.
& pedal end of both arms and the chainstay when the crankarm passes the frame,
or there will be none when you tighten down the bolt.