I wear these when it’s below 40F :
They aren’t designed for MTB but they work really well. Super comfortable and stretchy enough to not notice when riding. If it’s below freezing, I’ll wear a base layer under them and stay very comfortable. I haven’t had any issues with them getting caught in my 1x drivetrain. On 2x or 3x drivetrains, I just use a safety pin to tighten the cuff.