I’ve been doing a lot of mountain uni riding and my knees are killing me. I have raced mountain bikes for a long time. I can’t figure out if it’s the time spent on the unicycle, the intensity of holding back on the downhills, or the impact from jumping off and landing on my feet. Do you have any information on knee pain and riding unicycles and how to avoid it?
That’s part of unicycling, your legs, mostly knees I find, get really tired.
You get used to it.
Well, it is part of unicycling, but you have to pay attention to a few things… Saddle height is really one of the most important things considering knee and lower back problems. I’m not sure but I think the pain is from holding back on downhills, this is easier on long cranks so if you could post your wheel size and crank length that would help a bit. I have never had problems on my 24" w/ 150mm cranks, but have had problems with my 29er with 125mm cranks (same trail), you do get used to it but put your saddle so high that it is nearly uncomfortable to ride like that, about 2-3 fingers between your crotch when you are standing on the pedals.
I mentioned lower back problems, but that is more in trials so you won’t be bothered by that.
you get used to the pain if you are in shape. If you are either old or fat you should not ride a unicycle and should go back to the gym or your retirement home! 
Is there pain on the kneecap or what?
sretrinity, I have the same problem. I notice the pain almost exclusively on long, moderate to steep, downhill while trying to brake with my legs.
There are a couple things you can do to ease the pain. First, try riding in a more aggressive (forward) position. If the downhill isn’t terribly long, you can probably handle the run-out at speed. Most of the riders on here that don’t experience this pain are either very young, or have the technique and strength necessary to prevent this pain.
Second, raise your seat a bit. Hold onto a wall, mount your unicycle. Get your pedals into the up\down position (non-power position). Place your heel on the lowest pedal. Your knee should have a slight bend for road riding. Your knee should have moderate bend for muni.
Eventually, as you get better, you’ll find your own personal sweet spot that provides maximum comfort, with minimal or eliminated knee pain.
When I first started riding Muni, it was definitely something I had to get used to, and yeah, my knees and especially quads would burn after a ride. Make sure you have just enough air in your tire so you won’t bottom out; it will greatly add some needed cushion, plus make sure you wear shoes with a good thick firm sole! Old, flimsy, thin soled shoes suck and all those drops and jolts will go right through and up into your legs and you’ll have pain, especially later!
Although I sometimes think directing people to use the search button can be a bit rude, I think in this instance there have been some interesting discussions on knee pain that might be found in a search. You might find these useful.
If you just doing tones of ridding your knee mussels may be building
suck it up both my knees were crushed by a car
story?