Sam Brown and Henry Nelson know each other’s strengths and weaknesses. Nelson can climb. Brown can descend. Nelson is from Kansas and lives in Durango. Brown — born and raised in Eagle County — knows the Bighorn Gravel course like the back of his hand. On Wednesday, the former Fort Lewis College teammates — staying together at Brown’s house for the weekend — went for a little pre-ride outside Eagle. On Saturday, they duked it out for the Ram’s H…