This video by Lennard Zinn shows how longer cranks give tall cyclists more power, less fatigue, and better cycling performance in general. The video shows the difference in range of motion of 6'6" Lennard Zinn between 180mm and 205mm cranks. Tall cyclists should have longer cranks than riders of average height, and short cyclists should ride shorter cranks. Once you watch this video, you'll get the idea. Zinn Cycles sells cranks from 130mm to 220mm long for road bikes and mountain bikes. Visit this link to learn more about Zinn Custom Cranks: http://zinncycles.com/Zinn/index.php/...