Your right Alan...and I follow roughly the same approach, only balance charging once in a blue moon or on the odd occasion I want maximum range possible by charging everything up to 4.2V.
Anyway, the potential sizing issues with making the battery fit inside the frame was really beginning to get to me, so I spent the time to disassemble the bike tonight and test fit what I've got so far.
The rear 2S section that is already complete with thermal padding and 2 layers of heat-shrink only just fits. It's a very tight fit, and kinda just squeezes in there without too much shuffling. This was kind of a fluke, but a good one since this pack will be sitting there with nothing below it...I still need to think of how I'm going to secure it, but probably just zip ties with a bit of padding.
Next I CAREFULLY test fit the main pack. It's currently only mildly electrically insulated with a layer of hot glue on the top side (the bike and pack are upside down in the shots below) and even less insulation on the bottom side. I was extremely nervous sliding it in, but my desire to know if it actually fits overcame my fear of it shorting out on the frame.
As you can see, it currently does fit.
I did have it slid in further, almost all the way, but pulled it back out to take the photo's so you can see how tight it is.
I was planning on putting thermal padding on both sides before heat shrinking over, but now I don't' think I will be able to put any on. I think I will still add a thin layer of 1-2mm padding on the bottom side as I have just enough room for that. Interestingly, it looks like I might still be able to fit my CA and other electrical cables above the pack. I'm not too sure about the brake and gear cables though, and given the tendency for those cables to move under tension, I don't think I want to place them right next to my pack where they could easily rub through the thin layer of heat shrink.
Apart from that...this is the first time in a long time I've taken apart my rear wheel drop-out's/torque arms, etc. I really need to do something about all that as it's a real mess and I fear disaster at some point if I don't put some clamping forces on the twisting axle. The dropouts are spreading, my torque arms aren't holding very well, and the bolt on steel drop-out's I added are starting to rust.
My recent success with designing and having made some replacement clamping torque blocks for my Stealth Fighter
has inspired me to come up with a more permanent solution for the Bike-E. Once I'm done with all this battery stuff, I think I'll get to work designing and getting made some similar clamping drop out's for the BikeE. They will have to be either bolt on, or clamp to the existing drop out's in some way, but I'll worry about that when I start designing it.
Would anyone else with a BikeE also want a set? They would not be cheap...my prototypes for the Fighter clamping torque blocks were about $100USD + shipping each. Unless I could get at least 10 people interested, the price would probably be the same as prototypes for just a handful.