I live in Alaska and have a very nice 907 lynx fat bike. I am a small person, 5 feet tall and about 125 lbs. My hubs bought me some narwhal (studded) that are 3.8’s and I figure since I am small, these will be fat enough but am wondering if fatter is better? Is it worth the extra weight to after also since I spent a bunch of money on a cabon bike? Thanks for the help.
Fatbikes are the snowshoes of the Mountain bike world. The bigger the snowshoe, the more flotation you get on soft snow. The same is true for Fatbikes. The taller and wider the Fat tire, the more flotation you get on soft snow. If your trails are well groomed and firmly packed, 3.8 tires will likely be fine. If your trails are very hard packed, 3.0 tires might work. If your trails are soft and not well groomed then wider tires might be better. The best thing would be to buy a bike that at least has clearance for a wider 4.5-5.0 tires. That way you could switch to a wider tires if you need it.
If I were you being only 125 pounds, I would roll with what you have and see how it works. I am much heavier than you and I roll with 4″ tires in snow. Thinking about it, 3.8 inches is not that much smaller than 4″. I ride in Michigan and Ohio, we don’t get as much snow as Alaska but we do get it and 26″x4″ tires get me around pretty well.
Studded tires are good if you deal with icy conditions often, and they are expensive. Since you already have them, that is another reason to roll with what you have.
Fitalaskans, I am a bean pole on a fatbike in snow country. I can see the 3.8’s being a great choice for three seasons. Honestly, I would recommend 4.5-4.8 for the improved flotation they offer. Bikenerd said it well… I weigh between 130-165 and have two Mayors going that are well suited in large tires. The most supple, flexible tires money can buy will be the way to go. The less effort to squish the tire, the less you sink before they become snowshoe like with a wider/longer footprint.
Sarge III. Sarge is a plus/midfAt that wears 3.8/4.0 on 70 mm rims. I had the opportunity to put the bike to the test last Sunday with 12″ of fresh, delicious powder on the ground and still falling Monday morning. I discovered that 27.5 x 3.8/4.0 was doable and worked better than expected.
3.8/4.0 and 4.5/4.8… 3.8/4.0 requires pressure drop sooner than the larger mentioned.
One cannot be afraid to wrinkle the tires full time for many snow rides. Drop the pressure in increments. Carry a reliable pump, you will use it more than you think.