One of my new interests has been rock climbing. A group of us Yahoos try to go once a week. This week marked our seventh expedition. We've been gradually cranking up the difficulty of the climbs.
The rock climbing gym that we go to use the
Yosemite Decimal System Class to rate the difficulty of various climbs. The climbs that we do are class 5.
[Class 5] is considered true rock climbing, predominantly on vertical or near vertical rock, and rquires skill and a rope to proceed safely. Un-roped falls would result in severe injury or death.
While the top grade was 5.10, a large range of climbs in this grade were completed, and climbers realized a subdivision of the upper grades were required. Letter grades were added for climbs at 5.10 and above, by adding a letter "a" (easiest), "b", "c" or "d" (hardest). The difference between letter grades is roughly the same as the difference between number grades that are below 5.10. For example: Going from a 5.12a to a 5.12b is just a difficult as going from a 5.7 to a 5.8.
The gym has climbs that range from 5.1 all the way to 5.13a. We all generally started with 5.6-5.7 climbs. 5.9 seemed very difficult and 5.10a seemed unattainable. After going this many times, the group I climb with can do 5.8 and 5.9.