Which government office in Finland determines
design standards for bicycle paths (width,
traffic separation, signage, snow clearing, etc.)?
Please visit the site of Network of Finnish Cycling Municipalities: http://www.sll.fi/verkosto/engl.htm . There are some useful addresses at the end of the page. Email address of the co-ordinator Tapio Linna is firstname.lastname@example.org .
In Helsinki the municipal organ is Traffic Planning Division in City Planning Department. The pages are unfortunately only in Finnish and Swedish: http://www.hel.fi/ksv . One of the contact people is Antero Naskila email@example.com