I don't want to drill into the frame of my ebike, so I came up with the idea of fixing the battery cradle with water bottle clamps or something similar. Is this a good method for fixing an ebike battery to the bike?
I used a few clamps just like that from a water bottle to hold on my ebike battery. Just a warning though, those clamps are made with unique tube OD's and so they have zero tolerance so you need to be exact with the tube diameter.
I've also had success with stainless hose clamps for securing batteries on previous ebikes. They are great as the don't come loose and are very strong, really cheap, and you can get them anywhere. Make sure to use the good quality ones though!
I ended up ordering these from Axia Alloy - 8mm thread. I like how it has a wider bracket platform, it should give more stability. I agree with you, the size needs to be pretty much spot on. I can return these brackets if they don’t fit. I like the hose clamp idea but it looks cheap. Maybe some black heat shrink over the hose clamps could make them look better?
I ended up finding this fork mount on an online store which mounted to the down tube just as well. For $20, this was a pretty good deal, I'm a sucker for anything CNC'd out of billet, which I believe this is? The stainless clamps were also included.