Other units of measurement are intended for other things. The more arcane, the more closely they relate to the subject at hand. Feet and meters are intended to measure distance or size on any axis. Climbing, however, is meaningful not only on on a single axis, but also only in a single direction. You say a ride was 2,900 feet, and people will assume you didn't meant that you merely went around the block. You say you had 2,900' of elevation, they'll also assume it wasn't all downhill. But you say you got 10 climbing units, well, there's no question, you did some climbing!

Consider the question: how tall is a hill? Sure, that's like asking "how long is a piece of string?" But an ascent 1% of the height of Everest certainly constitutes a hill, or some kind of climb anyhow, and I think most would agree that while it's not a mountain, it's certainly more than a "bump." Within a mile or less, certainly within a kilometer, it takes real work to ascend, and if you see it all within the normal horizon distance (about 3 miles), it may be relatively easy, but you'll recognize that it's not flat.

The thing I really like is, not only does this single unit relate to something understandable, but so do orders of magnitude.

- 1CU = a single hill, or only nominal climbing over the course of a ride.

- A scale of 1-10 for a friendly 2-3 hour group ride: 1CU = easiest, 10CU = challenging.

- A score or more CUs on a ride = a Major climbing ride.

- Scores of CU on a ride = extreme

- 100CU = like, only the most perfect climbers achieve this on a ride.

- 1000CU in a year = that's a lot of hills!

What's also nice is that since it's based on the elevation of a mountain out in the world AND a specific climbing accomplishment, it's not arbitrary. The unit is about the subject at hand.