How about the Presidio for riding? I am not a cyclist. I incurred a foot injury recently, and have been thinking of ways I can exercise without impacting my feet too much. I've thought riding a bicycle around the Presidio could be pretty nice.
As long as you stay away from the bridge and the packs of tourists, sure. But I quickly found myself wanting to over the bridge to get different/more challenging routes.
It’s not very big, is the problem, and is often full of tourists.