Since I built this bike, I've been using a backpack strapped over the seat to transport my gear each day. It's never been an ideal solution, but I've managed to put up with it for the most part.
Recently, after having to repair my seat mesh (again) and having the backpack fall off a number of times during rides, I decided enough was enough and I would come up with a more permanent solution.
My criteria for a replacement was that it had to be very quick/easy to attach/remove (I'm tired of having to stuff around with elastic straps every day), and it had to be the right size/shape to fit comfortably behind the seat on the tail section of the frame.
I college of mine has a Topeak rack mount bag that caught my attention when I saw the bottom of it and noticed the grid pattern of ABS plastic. I realised that it was about the same width as the tail section of the BikeE and a bunch of carefully placed strong (N52 Neodymium) magnets might be enough to hold it to the frame and still make it easy enough to remove.
So I ordered a Topeak MTX Trunk Bag EX, a bunch of N52 magnets (not cheap for the genuine ones!) and some very strong epoxy (Devcon Plastic Steel).
I had to order magnets at about half the size I needed for each slot as there were not any magnets the right size I could find. Once I had them in hand I realised they would fit stacked so went with that configuration, but used more than I had so changed back to the original plan for the last 2 slots. I couldn't manage to get any magnets to stay for one slot as the way I had done it meant they would always propel themselves out while the epoxy was setting.
I'm not too savvy on magnetic fields, so not sure if this is the best configuration for magnetic strength but it seems to be ok.
It's hard to see, but over the top of the magnets is a piece of thin clear plastic. This was just some left over packaging, and I added it to try and prevent any of the magnets pulling out of the epoxy when the bag is lifted up.
Next I had to roughen up the tail of the BikeE. This was painful, I have to admit, but there was no way the epoxy was going to bond to a smooth flat surface like the anodised aluminium of the tail.
Some course sand paper made quick work of the finish and I was left with the bare aluminium.
Then the magnets got added with the Devcon epoxy (I just used generic clear stuff on the bag). I had to be very careful to match the magnetic fields as I went and I used additional coin magnets underneath the frame to hold everything in place as it dried.
I also added some magnets to my tool bag which sits underneath the tail and this helps hold it in position together with it's strap.
The magnetic force holding the bag on is not quite as strong as I had hoped, and the bag has a tendency to slide off to the side, so I also added some velcro (hook n loop) in the gap and end of the tail. This does seem to prevent it sliding, however it can still roll off in strong cornering.
So I need to make use of the spring loaded latch at the front of the bag. I think that if I can make something for it to latch onto that is attached to the frame or seat, I won't see any issues.
My initial thoughts were to make something out of wood, as it's what I have on hand. Ideally I would 3D print something, but I don't have a 3D printer (yet) and the only other option is to design something and send it off and hope it works out...could end up being costly.
Does anyone have any suggestions?