You can't use the max speed in WKO with the Garmin. There are speed spikes that will give you something absurd. Don't worry about your max speed, it doesn't mean anything. If you do want some idea, just look at the graph, find where the high points are and zoom in. Find a few seconds at the peak without a spike and check the average over those seconds. WKO is showing the data without any kind of smoothing, whereas the garmin unit does smoothing on the data before it displays it on the screen.