wolf pack
If I was thinking long gun, it would probably be my Mossy 500 with the ATI stock, etc. Short, light, extended mag, etc.
We rarely see a wolf where I am - the nearest established pack is over 50 miles and across the Mississippi, so the river has to freeze before the young, roaming males cross this way. That said, about 10 years ago, while on stand deer hunting in the State park about 12 miles from my home, in very deep snow, I had a young male wolf come within about 25 feet of me - truly a beautiful sighting. As soon as he became aware of me, however, he was gone fast.
My thoughts are based on the risk I do prepare for - coyotes. I hike/snowshoe daily, and both areas I go in, one right out my door, the other a wilderness park about 5 miles away, have well established packs. Winter means dark, and I am usually out in the deep woods late at night on snowshoes with two labradors. The yotes in this area can be robust - either because they eat so well or because of rumored domestic dog interbreeding, so there are some 50-60 pound critters. The labs stick together, and two large males is not the typical prey for yotes. Still, occasionally the yotes have followed us, and one will come in to try to lure a dog in. My guys are wise to that - they come together and return to me on alert.
I went with my Glock 17 with 147g Hydroshock. I use a rail mounted M6 laser/light combo. I carry with the 17 round clip and carry a spare standard mag as well as the 31 round extended mag in the fast access weapons compartment of my camelback Demon concealed carry pack. my thoughts - fast, easy to carry, total of 65 rounds easily accessible of a reasonable round at close range for a 50-60 lb. canine.
How do you plan to carry the SKS on the mountain bike - on your person or attached to the bike?