I love unicycling, but going down hill is ruining knees. I don’t know what to because I’m addicted.
If you guys could give me any tips to ‘save’ my knees that would be great.
Unicycle or Die!!
Do you use a brake?
No, I have a 20", would a brake help?
You don’t need a brake on a 20". However, if your cranks are short, that could be adding stress on your knees. You could try a pair of longer cranks. If you’re into downhill, I suggest you save your money and get a muni with a brake.
On bigger wheels a brake is definitely a help on steep downhills. On a 20" it’s probably overkill, although I’m sure somebody out there has done it.
What length are your cranks? As long as they’re at least 125mm a 20" should be ok on most hills.
Get some strengthening exercises for your knees and legs.
Unicycle in moderation.
Too much of anything isn’t good.
Ok. Thank you for all the replies! I will definitely try some of these things out and save up for a better Muni!
Unicycle or Die
Constantly having lots of pack-pressure on spinning cranks can also contribute to some odd muscle imbalances.
Swimming with a flutter kick (front crawl etc.) and/or just sitting in a chair and straitening your leg can help strengthen opposing muscle groups. When my knees went wonkey my physio told me to do 3 sets of 10 leg straitenings for each leg 3 times a day and it did wonders.
See a physiotherapist or other specialist that can give you a proper evaluation and a schedule of specific correction exercises.
Leg curls comes to my mind for some reason. Ask around if those might help.
muscle imbalance
Saskach…makes a good point about muscle imbalance.
What’s the solution? It’s obvious but counter-intuitive.
Do the opposite!!
Now I’m not going to waste my time explaining the biomechanics…
because(unless your a beginner) you all know the difference that seat/crank dimensions make.
If you are riding tall seat & short cranks? Do the opposite.
Ride low seat & long cranks?
…or vice versa. Get out of your comfort zone and try something different.
Different feel, different stress = possible cure.
I’m sure you’ve tried many things already, so if you haven’t already?
Give this a try, it might work.
Switch it up and stick with it.
I used to have bad back/shoulder/wrist from playing too much tennis. I cured it, though! How? I switched hands from righty to a lefty? Sure I had to re-learn everything. Sure I sucked as a beginner, but guess what. No more pain in back/shoulder/wrist.
Good luck…keep on!!
It could be that you’re just putting too much weight on your feet and you’re not seating enough into the saddle. The idea is to spin the pedals under you, whilst your weight is on the saddle, and the balance is achieved via the hips.
At the beginning, riders tend to put a lot of weight on the pedal, trying tame the beast that way. Which is why riding 500ft is exhausting with jelly legs at the end. The joints don’t like it either.
Later on, you progress towards being lighter, and your joints and your legs will thank you. Unless you have bad habits engrained deeply and you’re still not light enough - I know what I’m talking about, that’s what’s happened to me and it’s taking a long time to retrain!
Just stop playing tennis. Nothing is more fun that uni-cycling anyways 
Put shorter cranks on often helps and put the seat up.
Riding with a low seat and longer cranks causes the unicycle to twist more, it is this twisting causes stress in the joints.
Roger
Here’s something that I do that may help. If the surface is mostly smooth, I try to imagine that the braking action comes from simply dragging the weight of my legs, rather than back pressure. You’ll have to concentrate on keeping your weight in the saddle more than the pedals for this. You’ll likely get going faster than normal, but overall I find it helpful. (I have a brake, by the way, but I don’t use it too much unless the grade is steep and/or long, or technical.)
Good luck! 
Ok, thank you!
I agree with the strengthening / stretching, seat hieght and frank comments. Taking two ibuprofen BEFORE I ride has done wonders for me. If they start hurting in less than 30 minutes or do, there is probably an issue you need to fix with set up or technique.
I prefer “Unicycle then Die”.
But tell us a little more about your knees and your unicycling. Are you riding a 20" on mountain bike trails, or pavement? How long have you been riding? How old are you? How’s your seat height (a picture or video would be useful there)?
Normally I would agree but maybe not for Ethan, it depends on his particulars. He might just be riding with his seat too low or something. That said, a brake is super-useful for preserving your knees on downhill riding. Also working your “supporting” or “opposite” muscles can make a big difference; unicycling only works your legs in that circular range of motion, while ignoring a lot of the muscles we use for moving side to side, pivoting, etc.
What should I do?, what should I do?
YOU SHOULD ACT LIKE A MAN!
Sorry I couldn’t resist, I’ve just watched The Godfather (Johnny Fontane scene).
Well, I have been riding on some mountain bike trails and some pretty steep terrain. In the beginning it hadn’t given me to much problems but my knees are just starting to hurt. I’m 13 and have been riding for about 2 1/2 years. I think a video would be a better representation of my unicycling, so…
My YouTube channel is called Ethan.Pete. I have videos of me unicycling that you could go and check out!
Thanks!
Just watched you Flag Rock video. Good stuff.
The 20 looks fairly proportional for you and it seems well suited to the trails for you. I don’t think I would be in too much of a hurry to go up a wheel size. If I were to switch out equipment for the sake of your knees I would consider going one size shorter on the cranks and adding a brake to drag on the downhills. The shorter cranks will help you stay smooth and reduce jerky movements and the brake will also do the same by removing some stress from your legs.
The brake doesn’t have to be anything fancy. I would consider a side pull caliper brake from a BMX. They don’t all have the same amount of clearance but I think you should be able to find something to clear a 2.5" tire.
If you do get a caliper brake mount it “backwards” to the rear of the frame to keep it away from the back of your knees.
For the leg straitening exercises I mentioned earlier I did a lot of them while sitting in class. Training the body and mind at the same time :p.