Last week I received my Angletech Aerotrunk. Previous posts here have discussed what speed gain the Aerotrunk might give. I conducted a roll down test on a 900 metre hill with and without the Aerotrunk using water ballast to compensate when the trunk wasn't attached. A Garmin 305 GPS cycle computer was used to collect the data. The results show that the Aerotrunk adds speed starting at 30 kph and at the maximum speed of the rolldown the Aerotrunk adds 3 kph. So max with the 'trunk is 59 and without it 53.