Not sure of the grades. I will check with a friend who does know. Went back and checked the length of the two climbs. One is a mile long and steep all the way. The other is 2.3 mi. close to as steep with a short flat in the middle. I recently switched from a standard crankset with 14X25 gearing to a compact crankset. I was using my lowest gearing and couldn't get out of the 50's for rpms. I did not change the cogs. I think the total elevation for the 42.7 mi. was around 2700 ft. Not really that much. Then again I really don't know a lot about what constitutes a lot of elevation on rides. The only other time I ran into the same issue with my quads was on a Memorial Day ride of 65 mi. with 4,000 ft of elevation.