Cycling Maps - How Detailed?

I don't own a 5X (I have an Epix) but I think the US TOPO it comes with is the 100k version and therefore fairly useless. The cycle map is undoubtedly the Garmin Cycle map that came with my Edge 1000. That's intended for road cycling. I haven't looked in detail, but I don't think any of the trails in the my area are on them unless they're designated cycle trails. I loaded my Garmin US 24k TOPO on my 1000 before I even started using it (they don't have a lot of the trails in my area, either, but they're good topo maps otherwise and they're routable, unlike the 100k), so I don't use the cycle map.

But it doesn't matter. You can load whatever compatible maps you'd like on a 5X, and you have plenty of room. I use the maps from openmtb.org, but there are other places where you can get OpenStreetMap derived maps for hiking/MTB. Those have all of the trails in the my area, most are routable, and the ones I use from openmtb.org are topographic as well. OSM maps will be updated much faster than the Garmin TOPO maps (which haven't been updated at all to my knowledge). Recent changes to the trails in my area are all there.

I do not know U.S. Topo, because I live in Europe, however this question is not so important because you can upload there also custom maps openstreetmaps and so on,they are pretty detailed. Europe cycling map which was preloaded I have never used so far because in all countries where I have travelled I had found better map than preloaded cycling.

I do not know U.S. Topo, because I live in Europe, however this question is not so important because you can upload there also custom maps openstreetmaps and so on,they are pretty detailed. Europe cycling map which was preloaded I have never used so far because in all countries where I have travelled I had found better map than preloaded cycling.

But are the OSM maps routable? What other features are not available to 3rd party maps?

Absolutely they're routable. Garmin uses a proprietary DRM, so if you look at a TOPO 24k in BaseCamp, you see relief shading to bring out the topography and you can use 3D view to get a good visualization of the topography. You can't do that with OSM maps. Some older Garmin devices, like my Edge 800, did relief shading, but my 1000 doesn't and my Epix doesn't, so apparently that's no longer the case. Otherwise, there's nothing Garmin maps can do that OSM can't that I've ever found.

The popular mountain bike trails here (North Florida) show up on the maps. Some of the less popular too. Some of the more obscure trails do not!

Tough to use while riding at speed but good for way point checking etc! i do remember the park trails being in more detail than the forest - which were just lines!

Thanks for the replies. Ended up getting the 5x, pretty darn nice.
It does have the trails I was worried about, so thats awesome. They are on BLM land, so maybe thats why?
I will still likely play around with the OSM and 24k maps (if I can find them for cheap).