So I think I found a simple trick for routing the internal cables. I run a 1x system so I had to run a new housing for the RD and a new hydraulic brake hose in my Workswell 062 hardtail frame. This process may or may not work with other frames but it took me roughly 30 minutes start to finish to run both (fork and BB were already removed). For what it's worth, I am mechanically inclined but this was my first try at internal housings.
What I needed:
1 - 6 feet of 4mm cable housing
1 - Shimano SM-BH90 SB brake hose kit
1 - Spool of .041" safety wire
1 - needle nose pliers
1 - long thin flat blade screwdriver
Here are the steps
1) remove the caps from the housing holes (if your frame has them)
2) run safety wire from hole near head tube down to chainstay exit holes
3) fold over roughly .125" of wire, crimp tight, flare end to make a barb
4) insert barbed end into appropriate housing approximately .5"
5) carefully pull safety wire while pushing housing. If it gets caught, slightly back off pressure, rotate hose, try again. Flat blade helps to guide it out of the exit hole
6) snip off hose / housing to remove safety wire
7) repeat steps 1 - 6 as necessary
Here are a couple pictures to help visualize the process. Thankfully this turned out to be a fairly simple job. I hope this helps.
