On Sunday we went on a nice midday ride with Stevil, acuteaero, and Josh (not sure he's on ES). We travelled a little more than 20 miles on bike trails and roads in the vicinity of Forestville and Sebastopol. Speeds were leisurely at 15 with the occasional burst up to about 25. This was not an efficiency contest, still it is interesting to see the trends. All I had along camera-wise was my cellphone, but here are the vehicles:
Alan's BMC'd EbikeE
Stevil's Ventilated Xlyted Greyborg
acuteaero's Xlyted BMX
Josh's Magic Pied Tadpole TerraTrike
Over this trip the BMX and Borg travelled a bit faster and more spirited, and the Tadpole and EbikeE a bit more lazy and smooth. On the downhills at low speed the EbikeE would go faster than the Tapole. At higher speeds the Tadpole would glide away from the EbikeE, so we could see rolling resistance (and cogging) vs air resistance in action.
At the end of the trip the watt hours per mile were about 15 for the EbikeE and Tadpole, and 25-30 for the BMX and Borg. Not a precise A-B comparison, but interesting nonetheless.
We also traded bikes a bit and Stevil, acuteaero and I got to experience the three uprights. Quite a difference and range of riding comfort and position. The BMX is small and harsh, even with the Thudbuster it is noticeable. A softer seat may help. The small wheels and short wheelbase is likely part of the cause.