I don't believe SM went missing during a bike ride.
But in the interest of discussion, I encourage everyone to go to Google Maps, and use the street view of Hwy 50 west of Maysville. You'll be able to "see" the terrain, and why I think it highly unlikely that neighbor JR saw SM leave her house for a bike ride. The houses are across the river from each other.
Start your "drive" just west of Maysville, and travel along Hwy 50, until you get to the Monarch River Estates sign, which is the entry to Monarch River Drive (to the right after turning off the highway) and Monarch Estates Drive (to the left after turning off the highway).
Turn the "driving" camera angle to the south (left if you are driving up the highway to the pass), and zoom in to look at Monarch Estates Drive road to your left. You will see a flat concrete span (might be a large culvert) that is the bridge over the South Arkansas River, and will give you some idea of what the bridges on the other subdivision roads probably look like.
Monarch River Drive, to the right after turning off the highway, is the road JR lives on, which is across the S Arkansas River from the Morphew house.
If you continue "driving" up the highway, turn to the south on occasion, and you will see the Morphew house across the way. The high roof peak with the large windows will be visible over the trees from the highway. Continue on up the highway, there are two homes on Monarch River Drive, JR's house is the second house in the trees on the highway side of the river. The structures are not totally exposed to the highway, but are somewhat visible through the trees.
This can get a tad confusing, but stick with me.
If SM went on a bike ride, she would have ridden down her driveway to Puma Path, then turned right, which would take her close to the river and a two-track trail, or she walked her bike across the river and up to JR's house.
Yes, there could be a small walkover bridge between the two homes, but JR's house is on a cul-de-sac, meaning after leaving the cul-de-sac, SM would have had to either go west across private property (several lots) and the river again to get to County Road 225. Or she'd have to take Monarch River Drive east out to Hwy 50, and ride along the highway back to the west to the trailhead.
Or there is one way for SM to ride close to JR's house. If SM turned right out of her driveway onto Puma Path, it looks like there is a two-track trail that passes below JR's house on SM's side of the river, then it curves back up to County Road 225. The two-track crosses private property, but it is vacant lots, so probably not an issue. SM might have been visible to JR if JR was out on a deck or looking out a window at the time SM rode by down below.
It's hard to tell on Google Maps if the two-track is rideable. But in any case, I think SM riding by JR's house is too complicated and unnecessary for SM to take that route.
I'm fairly certain SM would not have ridden by JR's house. It's out of the way, and in the opposite direction from County Road 225 and the trailhead to the west. It appears that there are several choices for places to ride at that trailhead at the junction of Hwy 50 and County Road 225.
I think it more likely she turned left out of her driveway onto Puma Path, and passing one driveway and house, rode to County Road 225, where, again, she could go left or right. Left takes County Road 225, past one driveway and house, to a trailhead area by Fooses Dam and Fooses Lake, where the road turns into the Colorado Trail.
Right takes her toward Hwy 50 and the trailhead, in which case she would cross Fooses Creek (likely just a concrete span like on Monarch Estates Drive as mentioned above). She'd also cross S Arkansas River, probably across a concrete span like the one across the river on Monarch Estates Drive. So not bridges in the truest sense of the word, or how many people are imagining a bridge.
Again, I don't believe she went on a bike ride. But if she did, it is HIGHLY unlikely that neighbor JR saw her leave.
I'll try to post some screenshots of the Google Maps streetview I took as I "drove" the highway, but I encourage each of you to go and look for yourself at the area. I think it would eliminate a lot of the inaccurate and unrealistic posts about the roads and highways and waterways and neighbors, etc. This is a rural area, and the idea of subdivision here is radically different than a subdivision in a suburb of a city or even a town.
In way of giving some heft to my statements above: I live in a rural area, in a rural subdivision, in a mountainous area, with homes on private wells, and septic tanks with drainage fields. I'd absolutely live where SM does, if I were looking for a new place. Where I am now is very similar, albeit closer to the town area.
I'm also a retired CAD jockey--I was a draftsman, a mapmaker, using AutoCad for many years, working for an engineering firm. I love maps, which is how I orient myself wherever I am. Which probably explains why I like maps to show north UP. Always. Less room for confusion and misinterpretation.
As always, IMO on the statements that are my supposition.