Then be a trooper and fight the spread of misinformation. What part of what I said is incorrect? Not being snarky. I'm genuinely interested.

I ride 77" and I have no knee problems. I try to use my weight to my advantage. I have actually gotten to the point where I can spin the wheel backwards a bit while skidding and still don't have problems with my knees.

In the past I spent many waking hours trying to battle mis-information on the internet in vein. You'll notice that the people on here who are the most intelligent never chime in on all these topics, because they know the truth, and they know that they can't change the minds of the masses and it isn't worth trying. "but of course it is!" you might say. The problem is that the majority of the people carrying the mis-information are those who aren't thinking critically for themselves. It is so easy to convince someone of something false if they are making assumptions. When you read something enough times on a forum, you start to assume these people know what they are talking about. "Why should I re-invent the wheel and think about this. People have already thought about this and they can just tell me!" Trust me, it's a losing battle. (As I'm sure will be demonstrated in this thread as I'm overwhelmed by non-arguable responses that I'll ignore).

The people who do end up trying to battle mis-information just end up labeled like dutret (I hope you're reading this). While I agree about 0.1% with your approach (read:tact), I understand it to some extent. I agree about 99% with your content though, and I wish you the best of luck for the duration of this hopeless battle.

I'm not being snarky either, and not trying to single you out, but there is a lot wrong with your comments on the knee. I know enough to know that it is wrong, and I know enough to know that I'm not the one to explain the inner workings of knee issues to the world so I *try* leave it alone.

To make a basic comment regarding your earlier statement, you implied that the forces on the knee during pedal resistance (downstroke) are the "same" as during forward pedaling (downstroke). While the direction of the loading is the same, it's a pretty complex system and the magnitude of the forces is extremely different.

The technical definition of the word jerk (as in, you jerk your knee in the opposite direction to start skidding) is acceleration divided by time. When you're pedaling forward the compressive loading on your knees isn't bad (true), when you're resisting pedaling to slow down, the compressive loading on your knees isn't bad (true), what is being over looked is the exponentially higher loading that takes place during the change from the loading, unloading (direction change) and re-loading.

I'm not at all arguing the feasibility of braking distances and the moral choices of riding with or without brake. I'm talking purely about forces applied to the system (your knee).

I'm sure this isn't helpful so I'll just stop talking. I REALLLLY have too much work to do today to start a knee loading debate.

You have a good point. I won't make any claims unless I can back up what I say with non-anecdotal evidence.

Holy crap. You officially win the award for most mature response to an internet rant ever. If you come to San Diego I've got a tofu, potato and mushroom burrito on a spinach tortilla with your name on it!

^^ what about the loading on the knees when pulling up on the pedals while seated and pedaling a freewheel bike? its no different than riding a fixed, you just tend to do it more often on a fixed gear

I'm not saying that inherently a switch from push to pull is going to explode your face, I was just trying to say that the potentially hazardous loading from pedal-braking a fixed drivetrain comes from the drastic change in direction/loading. Not so much the resistance one you're already engaged in the act of slowing down.

I don't really see the point to this discussion however, since the people who ride brakeless understand the risks, rules and rewards of it and make that choice consciously (I hope). They are adults (I hope) and can handle the repercussions (I hope!).

i want food from random guy in SD </3

First of all i would like to say that the dynamics of pedaling a bike are quite complicated, and aren't going to be ironed out over an internet forum. people write doctoral theses on this subject! If its something you are curious about, there are a number of papers written on the topic. i might go try to dig some up in a bit if anyone is interested.

but for the sake of discussion and maybe making this thread productive, ill gander a bit of an explanation as to why i think resisting has a greater potential to hurt your knees.

for one thing, effective braking/resiting will consist of very high rates of deceleration. that means lots of force, more so than just casually pedaling. lets just estimate the amount of force that gets transmitted through your legs during a hard stop is similar to that of an all-out sprint. thats a lot of force.

Now, consider the way your legs work in a sprint relative to how they do while stopping. while in a sprint, the forward pedal (with the leg extended) is pushing down and the back pedal (with leg curled up) is pulling up. Whereas in stopping its reversed. the back pedal is pushing and the forward pedal is pulling.

your leg produces the most pushing force when it is almost fully extended (like when you jump up). you cant push very well with a curled leg (as anyone who has tried to ride fast with too low of a seat will know). so, a huge amount of force goes through the leg pulling up (front leg) to compensate. your leg evolved never having to pull up with any more force than needed to lift your leg (like to go up a stair, or on a freewheel bike). The muscles and the angles of the joints cant develop much force this way. So what i see happening is your hip muscles hold your thigh up (90* to the torso), and then the pedal pulls your calf down, with all the force between the two going into stretching (instead of compressing, like it was design for) the ligaments of your knee. Ouch!

I wont claim to be an expert on bio-dynamics, and again encourage people to find reading on the subject. but just look at your leg. it's made for pushing, not being pulled on. maybe that will lead you to your own ideas about the subject.

I have never heard of the bubbles of fluid theory. I am an orthopedic nurse in the OR at Stanford and I have never heard the docs speak of gaps or bubbles of fluid. Tears in the medial meniscus is what we mostly see....as long as we don't crash like some of those guys in the skid competitions....we shouldn't be messin with our meniscus on our bikes. Perhaps the pain some people are feeling is the stretching of the tendons and ligaments. Inflammed bursa in the knees as well as inflammed plica can also cause pain. Google plica and bursa.

^^ me either

personally I think alot of people have bad bike fit(too low/high saddle and bad pedal/foot position)...........then they get on and ride awhile, and because a freewheel bike is easier to ride and they dont get pains they immediately blame the fixed gear. Many also jump on it and get way over their head fitness wise too.

Im not buying it. People here want to put limits on gear ratio or insist on brakes, ok thats fine, so this implies rather explicitly that A) fixed gear is more than the human body can handle and B) the "unnatural" pedaling stresses are too much. This also means that guys like me must be freaks of nature, and Im not buying that either. Ive spent way too many miles riding and been thru the pains of what wrong bike fit does. Ive spent too much time riding fixed pain free to think its messing up my knees too. I also know it can take months of riding and small tweaks here and there to get a bike dialed in. The other people I know that ride fixed for work daily must be freaks too, and they arent. Heck we have one guy here that rides with a pre-existing knee injury and he's fine.

The more you ride in a short period of time the quicker problems will show as pain, same for just riding harder. Riding fixed just amplifies things a bit. You cant hide on a fixed gear. If youve got fit issues, bad technique, lack of fitness which includes tendon and ligament strengthening which comes with riding regularly, then yep, you get on a fixed and ride a bunch, and it can hurt. But you can get on a freewheel bike and do the same damage. This is one of the reasons prettymuch all the roadie training books require base training, besides cardio conditioning it also provides strength training for the legs so you dont tear something when the real hard efforts come later.

then you get pedaling theory from roadgator..........ok, how many people here apply more force when back pedaling with front foot pulling up than the rear foot pushing down? I dont, in fact I mostly push down. The front foot barely gets pulled on at all, just like pedaling forward, the foot pushing down does most of the work. As for skidding, anyone with lots of experience will likely admit that its a finesse maneuver, not brute strength, and standing with legs extended or almost extended they can handle lots of force in either direction.

Lastly, something as simple as foot position over the pedal freewheel or fixed can screw up your knees and put you off the bike. Been there done that. Culprit was as simple as toe cages that werent deep enough. Even only wearing size 10's it seems the cages that put my foot over the pedal where needed arent too common. I see people that ride for a living with all sorts of sins in the fit dept, it happens. Some take the time and effort to find out why and set the bike up so it doesnt hurt, others just blame the bike.

my knees can't be hurting because of fit. they feel fine with normal riding. they only hurt when i skid (which i do out of my saddle) - which is why i kind of want to believe this theory of 'our knees weren't made for this type of pressure'

Maybe i'll practice using less pulling and more pushing of the back foot...?

once again my gearing is 46x16 which seems to be fine in comparison to other gears i've seen people using.

It is definitely easier to push on the back foot than to pull. I think it is the pulling that is hurting your knees.

the only time I get knee pain is when i'm trying to keep the speed down on a long downhill, then I get to the bottom and the little pain I get leaves my body. So ride on brother, ride on.

I have been riding brakeless for several years. Only knee pain I have had has been when my pedal position was incorrect or I pushed big gears.

I think using lower gears, proper bike fit is and good genetics are all important.

When it comes to most serious athletes, knees and ankles are the first to go. No one in my family has ever had knee surgery. If you have knee pain on a fixed gear bike and none on a geared, listen to your body and don't abuse it!

My knees were hurting again like 4 or 5 days ago, I took it easy, took 3 days off the bike, and I'm feeling a lot stronger / better now. I think it's a matter of muscle recovery to some extent, because the pain I had wasn't right in the knee but slightly above so I think it was muscular and not a joint issue. Than again I'll also be the first to say that while I know a bit about nutrition and the organ systems and all that, I can't say I know a lot about muscles / joints / fitness info besides things like what to eat before / after workouts and why...

Either way, MSM also helped my knees when they were hurting from improper fit, I posted a thread about it in nutrition and some skeptical old guys got mad, but my knees feel better and they can be damned for having closed-minds.

I stated that as a sort of worst case scenario is one had clip-less pedals (it wouldn't happen that way with platforms or loose straps) and was trying to resist with all of their strength in both legs simultaneously.

skidding (and doing so with straightened legs) probably is better for your knees since its letting friction, and less so muscles and joints, do the work. but then you get into issues of control and ultimate braking power, and i was tying to keep this from digressing into a "just get a brake, problem solved" thread.

is it just me, or do you guys also feel more stable when skidding with your back leg NOT completely straightened out..?

no, its not just you, I do the same thing

My knees have actually gotten a lot better since i went brakeless, probably because i run a silly low ratio and spin like a madman insted of mashing, but still...

i've still been skidding once in a while to see if my knees can hold up - but still the same pain - feel like i shoudl lower my gear but 46 x 16 already seems low enough

^ ^ ^ take a break for a few days, let the the knees rest and rebuild.

i have a teflon kneecap in my left knee. I think because of my bionic leg i skid with no problems.

My knees are fine. But I strained my right forearm skidding.

Guy, you can totally go lower than a 75 inch gear. Quite a few people roll in the high 60s and like it a lot. Pop on a 17 tooth cog or 42 tooth ring and see if things improve.