I guess I'd start by asking if you have actually looked at the plan (https://www.muni.org/Departments/parks/Documents/PRC%2017-16%20STA%20Hillside%20(Final).pdf) or attended a meeting about the trails? The footprint of these trails is designated to a very small area of the park that was identified for high density use. The rest of the park will remain undisturbed.

Based on a study conducted by IMBA (https://www.imba.com/resources/research/trail-science/environmental-impacts-mountain-biking-science-review-and-best-practices) the impacts are no different than those of hikers. I'd wager that uncontrolled of leash dogs are a larger threat to local wildlife. The cause both stress and aggressive responses from animals and too many pet owners don't clean up waste.

I think it is time to talk about how we share the trails. We can all share the great outdoor resources this city has to offer but it means that we can't throw around stereotypes of crazy bikers and grumpy hikers.