Knee pads are necessary for mountain biking, especially if you lack confidence on a trail. Knee injuries off a bike can be very serious, and a good set of mtb knee pads can save you considerable healing time and loss of confidence.
Are elbow pads necessary for MTB?
Elbow pads are not needed for XC riding, that is fact, even if you fall off they were not needed for teh riding, just the crash that resulted!.
Do mountain bikers wear padded shorts?
Most mountain bike shorts are padded in the right areas to prevent soreness and allow the rider to get more mileage in before having to call it quits. No padding for your rear could lead to an early end to a fun day.
Are elbow pads necessary?
Elbow pads which are super useful if you find you fall backwards more than forwards. When you fall backwards, you will likely land on your elbows and your bottom. If you are a jam skater; elbow pads are needed when doing elbow slides, forearm pikes and similar moves.