I ended up going with a side cage for the bottle! So the bottle is now against the seat tube (light blue/turquoise) and the lock is now where the bottle used to be on the down tube.

Hm I don’t like that the blackburn cage is screwed in, from what I’ve read that’s apparently a bad idea for some 1.5kg lock. It seems like that’s too heavy for most frames and may cause the screws to break off. I wonder if there’s something similar but with pure velcro? It also seems like the metal might scratch the frame a tiny bit, the current mount I’m using is some sort of medium hard’ish plastic.

The other option looks better in terms of no screws, but an entire bag for a lock seems a tad weird!

I tend to only stop briefly at stores to get food and water, and I prefer stores where I can see the bike from the inside through the front windows!

Like, some generic velcro strap mount that doesn’t use these weird plastic flaps that apparently tend to let go mid-drive? Yeah that would be nice. Haven’t found anything so far…

For what it’s worth, here’s a photo of the seat tube mount that I’ve seen with review comments claiming the lock fell out during the ride (it’s an Abus mount, I got one of those Abus Bordos but not with this mount so far):

I wonder if anybody here has tried those mounts out?

This the type of velcro mount that I’m currently using on the top tube:

It is surprisingly fixed in place with just the velcro, there’s been no flopping so far. If you think it doesn’t bother the frame, what do you think would be the bad effect during a crash? It flying about or making a frame crack more likely?

(I do wonder a bit if somebody here has a top tube mounted lock and has any experience with if it had any noticeable effect during crashes!)