If you’ve had your fill of skiing, skating, sledding and everything else you do for fun on the snow, check out the latest ski town fad: fat bikes.

Fat bikes are all the rage in ski towns.

Instead of waiting until the roads are clear and the sun is shining to take your road bike out for a spin to get in shape, fat biking lets you work your cycling muscles year-round. They’re also great in mud season, as the knobby tires will float through the junky mess on the trails like it’s mid-summer. Sort of. But it’s become so popular in some places that they’ve even made a fat bike section of the Nordic trails available to intrepid bikers. The bikes are a pretty big investment—they’re not cheap—but there are places that rent them. You can’t really negotiate turns like you can with a mountain bike on trails in the summer, but with some pedal power it’s still a good way to do some hill training and it’s a fun way to get outside during the winter.

Check out Ramona Bruland’s piece on Plum TV for the skinny on fat bikes: