Reviving this thread to pass along a fairly major change in how I'm running the heater cable. We had a good discussion last season about the pros/cons of the different ways to run the cable. I was still running my cable up the back of the liner all last season, with the cable coming out at the heel, and then covering the cable with gaffer tape up the back of the liner. Well, I also use silicone spray throughout the season to make it easy to go in/out of my shells "racer style" (liners on my feet). Unfortunately, the silicone would seep into the gaffer tape, causing the tape to eventually fail around the edges. So I was replacing the tape about once/month. Also, I noticed that on my liners that got heavier use, I was actually wearing through the cable covering and exposing a little bit of the metal wires. Neither of these things were good, so I was considering what options I had to solve these problems.
Fast forward to today; I finally figured out a slick solution that I wish I had thought of long ago. Note though, that I really didn't want to bring the cable out at the arch since my footbeds are all already built with the cables coming out at the heels (with posting over the cabling too). That also eliminated bringing the cable out of the toe (a la
@SBrown). I have skied with the cable running up the back while inside of the liner (when testing footbed changes) and that sucks too. The cable ends up shifting and kinking and generally doesn't feel great right against your Achilles.
And then it dawned on me... similar to how I stick the heating element between the layers of my footbeds, I could run the cable up the back of the liner between the layers of the liner material. So I checked my ZipFits and sure enough, it's pretty easy to separate the layers of neoprene and padding that run up the back of the liner. I needed something to "open up" the channel and make sure I could fish the cable through this area. I decided to use a flexible, very fine tooth hacksaw blade. The hacksaw blade was the perfect width, easy to push up through the channel (separating the layers) and the teeth on one side could be used to gently widen the channel to fit the size of the plug on the end of the cable.
It took a bit of work to fish the cables up through the channels, but it worked. I cut a small slit at the top of the inside portion of the liner cuff to pass the cable out of. So the cable goes from the heel of the footbed, directly into the channel at the Achilles area of the liner, and the finishes through a slot in the neoprene up near the top. I put a small piece of gaffer tape over the cable where it passed through the slot to reduce any possible wear-n-tear on the neoprene. If anyone is interested, I can post some pictures.
In my indoor testing, I think I've got a pretty damn good solution. The cable is no longer exposed at the heel, so going in and out of the shell is a non-issue. I won't have to replace any tape due to it getting saturated with silicone spray either. When wearing the boots, I cannot feel the cable at all through the neoprene layer and I've also eliminated a layer of gaffer tape going up the back.
I think this is definitely a DIY proposition though, as I doubt skiers would be able to talk a shop into running the heating element cable in this manner. But you never know... I also have no idea if this is possible with other liners. YMMV.