Guys according to reaolem.com, the crank bearing of the M47N crank is 60mm, the same as the M42 and M47.what I meant by risky is that the front nose of the M47N crank is way too short, so a custom adapter has to be made to extend the nose,this would result in a two-piece crank, I would not trust a two-piece crank(especially with the chain sprocket beign in the extra piece)at 8000rpm...The guys at MM say it´s ok with their adapter, ok, go for it...