I haven't really found it...

What works for me is to click on the user's profile:
https://www.bikeforums.net/members/u...en-136384.html
As part of the URL, it gives the user's ID# 136384

Then I open up my own gallery (which by now the name is cached in Firefox).
https://www.bikeforums.net/g/user/392454

Now replace my user number with the target user number:
https://www.bikeforums.net/g/user/136384

And I get the album:

I don't know if there is a link or a search function, but this method is fast enough for me.

I do like to post the link back in case more photos are added. I like to upload most of the relevant photos, but sometimes there are more photos than I want to upload.

Also, of course, Bike Forums changed the method of uploading photos a few years ago. One can still access the old photos through one's own control panel (attachments), but I don't think one can see other people's old format attachments. Just pick out the attachment and use the [img]...[/img] to link it into the message.