I've been concidering as of lately to try some brevets of longer distances. I think that I also need to pace myself at a little bit slower speed. I recently did a race ride in florida that was 170 miles or 270km. I ended up not stopping at all while racing another endurance racer on a recumbent. I didn't feel too bad at all at the end of the ride...... not how I thought I would feel, but to continue at that pace would have probably put me into some major deficit. I ended up doing the 170 miles in 7 hours 4 minutes 43 seconds for an average speed of 23.38 mph. Moving speed was generally 26 to 30mph but got stuck at some stop lights so that ate up the average speed a bit. I would like to do a 300 km but at a 20mph pace might be better.