Today I did a monotonous, 1 hour easy ride - easing in at the start to a steady 42 or 43 km/h for the large majority of the ride - using an Elite Tuo trainer and the Edge 130 plus to record data.
Bizarrely, the average speed for the ride is indicated to be 60.1 km/h on Garmin Connect (looking at it on the web). Only a handful of erroneous spikes are visible reaching this speed.
Given the short time of the spikes (and their peaks) they can't explain the average. So what could possibly cause this sort of inconsistency?