Originally Posted by
cyccommute
I'm not all that trusting of the mobile devices use to measure speed and distance. I'm not saying that they are always wrong but they can be spectacularly wrong at times.
I'm with you on that one. I routinely see GPS errors with iOS/Android Strava apps putting riders well past 50mph, or having the GPS trace look like a lightning bolt rather than a line.
Going up takes a horrible toll on your average speed but going down doesn't add too much to it.
Ain't that the truth. My ride this Wednesday got me about 5000 feet of climbing-- the big section, from the Ranger Station to the campground, maintains nearly a 6% average for it's entire length.
10.3 miles, 3,115ft up, ascent time: 1 hour 48 minutes, 7.2mph
10.3 miles, 3,115ft down, descent time: 18 minutes 49 seconds, 33.7mph
So while the descent speed is great, it's still 20.6 miles in about 2 hours 7 minutes, for blistering 12mph average.