D8veh,Yes. It's made for it. 48v makes it run 33% faster and gives 33% more power. The 36v 201 rpm then becomes 48v 266 rpm, which means good power up to about 18 mph and assistance all the way to about 22 mph with a full battery and 26" wheels.
Hello D8veh,That's not the right adapter. the correct one has a curved side to match the frame and a flat side to match the battery mount. You can make one by wrapping your frame \nd the battery mount in cling film. Screw it on, then shove loads of fibreglass between them. let it cure, then file/grind it to a neater shape. Something like this, where I had to make an adapter to lift one end of the battery:
As for rocking side to side, I would still try and use the bottle hardpoints on my bike but the area that is unsupported could be supported with one of my mounts. I could still use velcro since all it is doing is giving support in one axis and the bottle mounts deal with the roll.That might work. You just need to stop it from rocking side to side.
I always add a third rivnut to the frame as well to give a more secure fixing. You can buy 5 mm rivnuts from Ebay, and you can install them with a 5mm cap screw and a two flat plates with holes in. No need for the special tool. Drill the hole in the frame to be a tight fit. Tap the rivnut in. Place the plates with the hole over it with the holes in line. Insert the cap screw and tighten it with one hand while you hold the plates down with the other. If the rivnut starts to spin, insert a screwdriver between the two plates and lever them apart so that you're levering up the cap screw to form the rivet underneath. That should clamp the rivnut enough so you can finish off by tightening the screw. Take the screw out. Job done!