My educated guess would be that they did it for the same reason as on @Breso hour record moser. When you have a narrower BB, you can mount the BB lower (without the risk of pedalstrike) which gives you an aero advantage, I guess. Since the bb spindle is considerably narrower, the chainstays need to be moved up to provide enough clearance for the chainring.
My educated guess would be that they did it for the same reason as on @Breso hour record moser. When you have a narrower BB, you can mount the BB lower (without the risk of pedalstrike) which gives you an aero advantage, I guess. Since the bb spindle is considerably narrower, the chainstays need to be moved up to provide enough clearance for the chainring.