Next summer I am planning to ride a bike from Belarus to the north of Norway through Finland. What measures should I take to be protected against wild animals (bears and wolves)?
None. Bears and wolves are no safety concern in Norway and Finland.
Both are shy and, since they are not used to human contact (opposite to say, some places in the US where bears are used to people) will try to avoid all human interaction. This will mean that they'll go out of their way to avoid you and very likely you won't see any.
If you ever do catch a glimpse of a bear you can congratulate yourself on your luck, take a photograph and follow the common bear safety advice (see for example this question). Apart from that no additional measures (such as bear sprays/bear hangs/bear canisters/...) are necessary.
Wolf safety measures aren't even a thing, as attacks of wolves on people are exceedingly rare and happen only under very special circumstances. You riding a bicycle on a road is quite surely not one of them.
Note that as @Tomas By has correctly pointed out there are other animals which might pose a bigger danger (or certainly a bigger annoyance): mosquitoes.