Since the Park District is revising its Master Plan, now is the perfect time to ask them to get mountain biking out of the parks! Mountain bikes, with their "aggressive" knobby tires and high speed, grind the trails into powder, which washes away in the first rain, leaving V-shaped ruts and degraded creeks and other habitat. Even the mountain bikers themselves, with rare candor, use the term "shredding the trails" to refer to mountain biking.
Countless insects, lizards, snakes, and other small plants and animals are killed by these "wheeled locusts". Hikers and equestrians are abandoning the trails and the parks, because it is unpleasant and dangerous to have to constantly be on the alert to avoid being hit by a biker coming around a blind turn at high speed. Illegal biking and even illegal trail-building are common in the parks.
It's beyond me to understand why mountain bikers insist on biking in the parks, when walking provides the best way to actually see the parks. Careening through them at high speed -- or even low speed -- doesn't allow one to actually see anything, since you have to give all of your attention to controlling your bike on unpredictable terrain.
It's high time that we restricted bikes to paved roads, where they can't do much harm!