Page 3 Modeling a Mountain Bike

Without any curves selected, go to ‘Surface/Sweep 1 Rail’. Rhinoceros will ask you to pick the rail curve. Pick it as labeled below.

Next, select the profile curve. NOTE: The reason that you cannot select both curves prior to the ‘Sweep 1 Rail’ command, is that the profile curve (due to it’s shape) could be like a rail, and Rhino then couldn't tell which was which.

As you can see, the resulting surface is quite dense compared with the other frames. Instead of using the default settings, use the Rebuild option as seen below. This makes the surface less dense, but still smooth.