Trying to identify an old Helkama I have recovered
Helkama Oiva is more or less a civilian version of the bikes used by the Finnish army. They are known for being very heavy but quite fragile for their weight. The rear rack is very sturdy and perfect for carrying M85 backpack with shoulder straps wrapped around seat stay and support strut. The lock, chain guard and dynamo mount are additions for civilians.

The unique stem clamp where instead of usual expander cone or wedge, the steerer tube clamps around the stem, is a major security hazard. The steerer tube has normal threads and a cutout to allow deforming the tube. The threads provide a great starting point for cracks. The stem should be replaced with one with wedge immediately, or at least at the first time you notice that the handlebar feels loose. I had one of these bikes (non-military style) that I loaned to a friend and it failed at traffic lights. Fortunately it failed when he was starting, not when riding. No photos, because this was before digital cameras.

The steering geometry is unusual by modern road bike standards, but common with old work and touring bikes. The low trail reduces wheel flop, and wide low pressure tires provide the stability. These bikes are meant for heavy loads, slow riding and gravel roads.

The bike is very probably from 90s, even though the one piece crank was already obsolete at the time. I recall Helkama using that logo at the time, and the Rautaruukki sticker is a response to to "Tange Hi-Ten" stickers that were appearing on MTBs at the time. Rautaruukki is a steel foundry most known most for building supplies. They have specialized in high strength steels in 2000s, but those are not marketed for bicycles.

The white paint on rear mudguard was required in Finland at some point. I don't know the exact history, but I think the rule was removed in the 70s. This one looks like hit has been painted afterwards.

I do not recognize the logo on register plate. My guess would be that it has belonged to a saw mill or pulp mill. The old logo for Forest Administration that you can still see in national parks is a bit similar, but not the same. The broken frame lock and spray paint imply it was stolen at some point.