why are bicycles excluded?

mountain bikes scare the horses

There is no need to exclude bicyclists. First, these are good roads thru wide open spaces - not narrow trails in woods, so visibility is great and there is plenty of room to share. Simply post signs that bicyclists must slow down to 10 mph or less when passing horses. Then fine bicyclists who do not comply. This what is done in the parks along skyline. I hike on Open Space trails every week and RARELY encounter horses! Exclusivity is a poor solution.

@wp - there's plenty of multi-use trails where it works just fine. this is obviously discrimination of one user group over another - and with public funds. boooooo to the MROSD on this horse puckey.