If you think mountain bikes and horses can get along, come camp at Snohomish County’s Whitehorse Campground. There’s some nice horse corrals that no one ever uses. There’s access to the Whitehorse Trail and North Mountain. Would be good early season riding, the snow melts sooner than the surrounding mountains.  There’s beautiful views of the surrounding glaciated peaks. A great chance to see them without being on the cliff’s edge.https://maps.app.goo.gl/bKLd3y5hj9N3xoZX7?g_st=ic