What does this bike have against my knee?
 

I've got three bikes: a Kona Jake, a Marin Muirwoods 29er and a Gitane Gypsy Sport fixed gear conversion. One of them seems to be causing my knee trouble every time I ride it. It's not the fixie. It's the Muirwoods.

Skip this paragraph if you don't care about the back story. I'm not entire sure how much this is reality and how much is my imagination. I've ridden this bike for 2300 miles, most of it last winter. I started having trouble with my knee some time last February. It got progressively worse until spring came and I started riding my Jake more regularly. By the time it went away, I had mostly hung the Muirwoods up for the summer. I've ridden it a dozen times or so since then, and it seems like every time my knee starts acting up.

So, I'm trying to figure out what could be up with this. The pain is on the inside of my left knee (distinctly not the front or back but the side). It feels like I twisted it. It generally doesn't bother me while I'm riding, but later in the evening.

I've spent a lot of time tweaking the saddle position--up, down, forward back. I tried putting it the same position relative to the bottom bracket as the Jake, which I've had professionally fit, but the Muirwoods has a different seat tube angle and this didn't feel right. I've got it in a position that feels pretty comfortable.

The gearing is different from the other bikes, but I generally don't mash. It's certainly easier that way than the fixie.

I've switched clipless pedals with the other bikes and that doesn't help.

The headset seems to come loose a lot on this bike. I don't know if that could be related.

My suspects are:

• Q-factor from the MTB crankset
• Loose headset causes me to twist my knee more than I notice
• Planting my foot while this heavy beast is still moving a bit at traffic signals
• Dismount from different position is twisting my knee
• Bike really needs fitting in spite of my efforts
• 39-year-old man should be blaming his knees, not the bike.

What do you think?

Does the mountain bike have longer cranks than the others? I had a mountain bike with 175mm cranks for awhile and it would bother my knees when I rode it after getting used to my other bikes. I am short and have 165mm cranks on my road and track bikes and 170mm on my mountain bikes.

I've parked my Gary Fisher 29'er for a similar reason. Left knee is flaring. Mine's an IT band issue, but I honestly think it's the stop/starts on the heavy 29'er taking it's toll. I always unclip the other foot coming to a stop, and mash with the left taking off. Dunno about yours, but mine takes some grunt to get rolling from a stop.

I can ride my Cross bike without issue, but it's also only 19lbs and less rolling resistance

-R

That's a good question. My fixie has a 165mm crank, but the Jake (which I ride all the time, including on centuries) and Muirwoods both have 170, so I don't think that's the problem.

You know, when the knee problem was at its worst last spring, I tried unclipping at stops with the opposite foot. The first day I tried it I fell over at a stop light as if it were my first day riding clipless. I unclipped in plenty of time, but leaned the wrong way. :o

Anyway, I'll bump that one up my list of suspects.

It could also be the saddle or the saddle angle. That could change how much your knee flexes.

Did you ever actually measure the Q factor to see if the other two are the same and the 29'er is different?

Do you watch your knee while you pedal? Mine used to sway inside on the upstroke, and I had to concentrate on keeping it from doing that. Some things online I've read suggest it's a matter of conditioning the muscles to work correctly, while others suggest shims for the cleats. In the end, I decided to pay more attention to my form, and the knee pain vanished.

It might also be you have a build of bad humors in your blood and you need to bleed out some of the bile. In that case I recommend finding a trusted bloodletter (phlebotomist, wanna-be goth "vampire", or similar) and letting them disgorge you of bad humors.

I like the cranks as the suspect. My MTB also has 175's, and it feels like I'm always pulling a touch more than I'd like at the bottom of the stroke. I imagine that could cause problems like yours if I were 39. ;)

Which means I have 7 years to get new cranks!

I don't quite understand the start/stop issue - when I'm decelerating, I always shift into a low gear and come to a complete stop as I'm putting my foot down. By doing that, I'm never using my feet to stop the bike, nor do I have to mash to get it moving.

Ah, for the olden days when a good leeching would cure what ailed you.

I moved the saddle from the peak problem time to my Jake and have used it all summer. I've got the saddle level on all three bikes, but maybe with the different riding position on the Muirwoods level isn't what I need.


Actually, I haven't. I've just kind of assumed it would be wider on the MTB cranks (Deore XT M770) accommodating, as it must for the wider chainstays. I suppose measurement is in order.

I'll try to take a look at that. I'm generally pretty form conscious, I think, but observation is always good.


Good suggestion. I'll try this first. :)

yeah I would look at crank length and pedal thickness as well as seatpost height; all else fails, even if it feels easier to pedal than the fixie, shift down anyway.

Crank length is the same between the Jake and the Muirwoods, but I do want to eye the cranks suspiciously because my possible solutions are: (a) pay for a good fitting, (b) get a new frame to serve this bike's functions, (c) get a new crankset, (d) all of the above.


I do that too (or at least intend to), but a quick look at the way I burn through the toes on shoe covers would seem to indicate that I'm not as completely stopped as I think I am when the foot goes down.

Interesting! I'd try fixing that. Although, is that something you only do on the one bike?

Other than that, it's pretty much things you already know about - seat height, seat setback, Q-factor. It could quite likely be a combination of things. From what you have mentioned, I might guess a seat that's a touch too high, and/or too far back?

Not that I'm aware of, but I only use shoe covers with the bike in question, as it's my rain bike.

Have you measured the difference in Q-factor for each bike? In a recent thread of mine about my heel hitting the chainstay, a popular solution was to install kneesavers (pedal extenders) on the pedals to position the pedals further out. Anyway, I haven't found much on the internet about what is the right q-factor, but the this article suggests that your pedals should be positioned so that your feet, knees, and hips are all inline. That makes sense to me, but I don't know how you would go about measuring that.

http://en.wikipedia.org/wiki/Q_Factor_%28Bicycles%29

http://www.bikeforums.net/showthread.php?t=578920

I actually did measure the Q-factor this morning, and I'm leaning toward that as the culprit.

Measuring from the center of the seat tube to the outer edge of the crank:

Kona Jake: 78mm
Gitane Gypsy Sport: 72 mm
Marin Muirwoods 29er: 88mm

I did this just before leaving the house. So I was wondering, would 10 mm make that much difference? Maybe.

On the way in to work, it occurred to me that I should have measured the pedals too. The Jake has Crank Brothers Candy C pedals:

http://www.crankbrothers.com/templat...andyc_grey.jpg

The other two both have Egg Beaters:

http://www.crankbrothers.com/templat.../eggc_silv.jpg

I thought these used the same spindle, but in the picture at least (a poor substitute for measurement, I realize) it looks like the Egg Beaters are longer, which would be good on the Gitane but bad on the Marin.

I guess I must have very narrow hips because I rode the Gitane in today and observed that my legs and feet were very straight. I'll have to look with the Marin to see if my feet are pointing out or something as I pedal. It wouldn't be much, but at about 8000 revolutions a day it might be enough to cause problems.

Perhaps I'll have to try the Crank Brothers short spindle kit.

You laugh, but after a week of rough camping on the Lost Coast, I awoke back in town (Blue Lake, CA) with my left ear locked to my left shoulder, a nasty knotty pinched nerve in my neck. This was intolerably painful for sure, but I had a series of planes to catch the next morning and could hardly afford to be totally broken.

My wife's professor referred me to his Chinese accupuncturist in Eureka.

A 90 year old Chinese doctor, who seemed about 60, performed a variety of treatments on me. The most dramatic was certainly when he used some sort of glass suction device to suck a cylinder full of blood from the knot on the back of my neck. It felt funny, but not painful. I wouldn't have believed it except that my wife was standing right there watching.

The "leeching" provided 80% relief instantly. Heat treatments, accupressure, accupuncture with electrostim needles, and two hours worth of memorable stories brought me almost back to normal. I continued my journeys without much discomfort and was feeling 100% in a few days.

One of the most fun, inspiring and rewarding experiences of my life.

I would chock this all up to the marijuana. ;)

I skimmed over this thread and might have got something wrong. I think the q factors you're stating are half a q factor as I understand it, but that's good enough. It looks like the pedal on the bad bike puts your foot even farther out, if I'm reading it right.
Tentatively I think a different crankset is indicated. I don't know how straight a crank you can have and still clear the chainstays on that frame, but I'd suggest getting the narrowest q factor that will fit and leave enough room so your heels don't strike the chainstay, and maybe use a pedal that doesn't force your foot out even farther.
I just hate bowed-out chainstays and it frustrates me that it's hard to find an affordable set any more that doesn't force that wishbone or inverted-V type pedaling. I've had knee trouble from it, too. Try to note, when your going up a hill, whether your knee involuntarily swings out to get itself over the pedal. That's what was happening to me and it really played havoc with my knees.

Right on all counts -- I did give half a q-factor (because it was what I measured and I thought it was good enough) and the pedals on the bad bike do put my foot out further, 3 mm more.

So, does anyone know a web site that will tell me the Q-factor of various cranksets?

is a crank bent?

I have seen a site with q factors for some cranksets, and I'm sure someone will know where it is.
Seems like one of your bikes has a q of about 142, and now you're out to, like, 176 on the troublesome bike, plus the difference from the pedal spindles. The Sugino XD sets I think are around 162 and will likely still clear the chainstays. I got that crankset from Rivendell and it's still a bit wide for my liking; just tolerable. The change from 142 to 176 is dramatic and is surely causing a subtle deflection or wobble in the knee. I'm no physiologist, but it seems like the knee's made for walking, running and standing, with minimal side-to-side flexion. So I think when you cast it outward and then do a heavy pushing-down job with it, you are giving it hell. I think that other person had it when he talked about having hips, knees and feet aligned. A lot of people do ride these wide mountain cranksets and have no problems, so obviously it varies. Good luck.

I used some pedals someone gave me and the pedal was narrow. my feet kinds hung off the ends and my left knee on the outside of the knee was really sore after 62 miles. needless to say those pedals are going to be used for any long distances, if at all

It could be that you have grown since you began riding the bike. The knee problems happened to me back when i was riding a bike about 3 sizes too small.