This past March 22 marked the day Sovich decided he couldn't take it
anymore. Over the forty-five minutes that it usually takes him to
hike up the canyon with his dogs, 17 mountain bikers came by. "They were
all polite," he remembers, "and there wasn't a question of either me
or the dogs being in danger. It was what this kind of use was going
to do to the canyon over time.

Ah, at last, we can cut to the chase. The issue has very little to do with mountainbikes vs hikers ... if there were 17 hikers also on that trail they would have caused similar levels of erosion.

I note also that this guy concedes that he did not feel threatened or endangered.

There is absolutely an issue ... we have to preserve the natural environment for future generations. My argument with you is that you seem to believe that hiking is entirely beneficial and mountainbiking harmful. The facts are that they are both activities which cause similar levels of erosion and there have to be user limits if we are not to destroy the things we love.