I wrote the MountainBikes copy. Some of it was composed on John Finley Scott's enormous steam-driven Hewlitt-Packard "Word Processor," the rest on an ordinary electric typewriter. The MountainBikes letterhead was designed by the same artist who did the posters for Repack, a fellow member of Velo-Club Tamalpais and my roommate at the time, Pete Barret. The photo of the collected bikes against the fence was taken just outside the shop at 1501 San Anselmo Avenue, and was at the time the most bikes we had ever assembled and had on hand at the same time.
The explanation of what a MountainBike was seems a little obvious now, not so much then.