For about five years now I've had problems on and off with my left knee. When I did all my riding on my old Specialized Rockhopper mountain bike and Flite saddle, I noticed the peculiarly assymetric way my thighs scuffed the leather top and how my knees sometimes clonked the top tube as I pedalled. I spent many a minute looking in the mirror and observing the odd alignment of my knee joints, from my femurs to my tibias. For a long time I thought it was just me, for this was in the days before The Internet, but indeed the third paragraph on Wikipedia's page about the tibia agrees with the comment from a friend that in women, the tibias tend not to be parallel, to compensate for more angled femurs. Of course no-one told my pelvis, which stayed narrow. The upshot of this was that my knees like to be close together when I pedal, but slightly to the left. Indeed, my Flite is more polished on the right-hand side but it's been so long since I rode an upright bike every day that I can't actually remember which knee would hit the top tube.
It didn't become obvious until 2005 when my Speedmachine arrived on the scene. I'd tested one in 2003 and around the same time that I bought my Windcheetah, and only rejected it because I was finding it so difficult to balance. By 2005 my thighs had put on weight, except I hadn't really realised, and all of a sudden the frame around the headset -- a meaty two and a half inches across of metal tube and cables -- seemed very wide. The bike is fast, comfortable and well reclined, but also relatively heavy, and hard acceleration to which I am no shrinking violet allows a lot of force to be put through my legs. By mid-2007 I was riding my P-38 most of the time, a bike which instantly felt "right" ergonomically. But the suspension of the Speedmachine is so beautifully, wonderfully capable, which was why I could never part with it. Bouts of riding the P-38 felt great, while bouts of riding the Speedmachine sometimes left me with sore knees and particularly my left; a situation normally rectified by some rest and riding my little lightweight Dahon. But not altogether an ideal set of circumstances: was I too strong, somehow?
Well, in the summer of 2009 I acquired Victoria, my monstrous American RANS V-Squared, complete with remarkably wide-feeling pedals. That was down to a pair of pedal extenders, a good 5/8" of extra Q-factor to each side, as fitted by the previous owner. I figured I'd give them a go, as my friend and I set out for the Erie Canal, but after the first day something in my left knee didn't feel right. By the end of the second day I was feeling serious pain in my left knee; halfway through the third day I bought an adjustable spanner and threw the pedal extenders away, and iced my knee that evening. After that, the pedals felt remarkably narrow, but not at all uncomfortable. The only gripe was the Truvativ cranks, whose fairly straight profile allowed less inwards heel movement than the FSAs on the P-38, the cheap Campag cranks on the Speedmachine and the Middleburns on Speedy. It didn't stop me notching up over 500 miles over the two weeks, and in fact only two or three days after junking the pedal extenders, the bike as a whole elicited my comment, 'You know, right now I feel absolutely comfortable.' My knee, which had been rapidly swelling up to the inside and becoming intensely sore to the touch, calmed down within days.
This year however, something went wrong. An earlier suggestion of a collapsing arch in my foot, an opinion seconded this year by my local running shop, combined with various part-diagnoses of pelvic misalignment caused by my feet, and my widely reported shoulder pains perhaps caused by my lower back and by extension, my pelvis, led me to a chiropractor initially. The motorbike crash, while not related, put me off chiropracting and shoulder pain put me off riding upright bikes. All of this led to me trying some special insoles. Rather than go clever and expensive with custom-fitted ones, at least initially, I was recommended an off the shelf pair of Superfeet. Superfeet come in various colours designed for different activities, foot shapes and so on and I came out with the orange ones, designed for big-footed people who spend a lot of time on their feet: running, walking, standing. And you know, with those inside my shoes and me clumping around, my feet had never felt more comfortable!
For about two months I happily swapped the insoles from cycling shoe to cycling shoe, to hiking boot, to trainer. They did feel strange for cycling, at first, but the arch support and heel location felt great. Then during another bout of enthusiastic riding of my Speedmachine, my left knee began to really, really hurt. In fact, it was so bad that I had to spend a week and a half not cycling at all, while grimacing every time I had to push the clutch pedal in my car, while vigorously burying my finger into the side of my knee to relieve the pain and massage the tendons. I also spent most of that time with an elastic bandage on my knee and several evenings with a bag of frozen peas in place. When my knee started to feel a bit better, I took the pedals off my Speedmachine and buried the bike behind Victoria in the garage. I put the Superfeet back in their box and put my original insoles back into my cycling shoes (how wise of me to keep them all!), and vowed to ride only the bikes I knew wouldn't hurt me again: my P-38, the V-Squared and, though it was still sitting clean and tuned up but unloved next to its American stablemates, Speedy.
Taking it gradually, my legs began to feel better. Every ride home is still punctuated early on by a solitary but solid click as my kneecap moves into place, and I try not to go breaking records unless I have a tailwind or a hill. Following a physio appointment last week, my knee has been hurting again. I think this was due to the poking and prodding he did to make an initial appraisal, and believe me, he certainly found the source of the pain as I yelped. More physio beckons, with some exercises to practice meantime. But something was nagging at the back of my mind: why did my P-38 always seem to feel right, and why did my Speedmachine always seem to be behind the outbreaks of pain? The physio mentioned words like "patellofemoral" and "meniscal", unhappily followed by words like "damage". I then realised that perhaps the accident in early 2006, in which I was broadsided on my left-hand side by a car whilst navigating a roundabout, and a subsequent accident in which I slid on the bike in winter, landing on my left side, might have contributed to some twisting shock to my knee.
So to return to the point of sketching pedals and booms, I spent this afternoon vernier calipers in hand, measuring my bikes. The findings are very, very interesting. I use Shimano SPD pedals, both PD-M520 and PD-M540 models, and Speedy has a pair of PD-A515 roadie SPDs. Happily, every one of these measured 54.5mm from crank face to mechanism centre. I then measured the boom diameter at the point at which the pedal axles pass, and the distance from the boom to the outer face of each crank where the pedal abuts. From this, I can determine the Q-factor for each bike, for both the left and right-hand sides. Knowing these measurements also lets me vet any potential pedal replacements, such as Crank Bros Eggbeaters, or Time ATACs.
| Bike | Q-left | Q-right | Cranks |
| P-38 | 135.0 | 133.0 | FSA Pro Team Issue, ISIS |
| V-Squared | 127.0 | 131.0 | Truvativ Elita, GXP |
| Speedmachine | 141.0 | 138.0 | Campagnolo Veloce, ISO-JIS |
| Speedy | 137.8 | 137.8 | Middleburn RS7, JIS |
Is it any wonder I've been having problems since 2005, when I more or less stopped riding Speedy every day and started on the Speedmachine? Is it any wonder my riding position on Victoria is off-centre and that it felt so narrow? Only the machine built in a small workshop in Manchester by one man, a machine designed by the master himself, Mike Burrows, a machine with a CNC-produced bottom bracket axle and whose cranks hail from the cream of British manufacture, Middleburn, is exactly symmetric in its Q-factor. My lovely P-38 with its full complement of FSA bling is two whole millimetres out. The V-Squared is a whopping four out. And not only is the Teutonic tour de force itself an uncomfortable three millimetres out right to left, it puts its pedals a whole six millimetres further out on the left than my P-38 and five millimetres on the right. The Campag cranks were never designed for the bike's JIS-taper FAG bottom bracket at all, and in my accelerative exuberance of pedalling and unwillingness to address the issue by disposing of the Campag cranks, my knees have probably paid the price. Fitting JIS-tapered cranks of the same profile would see the pedal centres move inboard by up to 4mm, according to the late Sheldon Brown, and this is consistent with the existing gap between crank and bottom bracket cup that is quite obvious when examining the bike, and consistent with the results I saw when I tested the Middleburn cranks on the bike instead (an experiment which, perhaps due to its dramatic effect and consequent lack of perseverance, was short-lived).
But more issues abound, too, such as why my left knee has the tendency to move inwards to brush the steering column of my P-38 at its maximum bend, despite that side being 2mm further outboard. As near as I can tell, the left and right cleats on my usual shoes (Shimano MT70) are identically aligned. There is the ergonomic difference of the riding positions of all four recumbents, where two of them enjoy 175mm cranks and two enjoy 170mm, leading originally to my theory that in a more closed riding position I preferred longer cranks for slightly greater torque, and shorter cranks on a more open, reclined riding position to allow me to spin the pedals better. Now that I have some hard numbers on (mis)alignment, there are even more variables at play, and it's making it almost impossible to draw any firm conclusions without having the wherewithal to conduct a series of tests such as varying the crank length alone; varying crank length while adjusting the gearing to the rear wheel; varying the torso-hip angle against crank length, and so on.
All I know right now is that my P-38 is fractionally out of alignment but not desperately so, to the extent that I do most of my riding on it; it's clear that my V-Squared needs a bit of work (I blame Truvativ's ridiculous GXP bottom bracket design, myself) with some washers and things; and if I'm to keep my Speedmachine and enjoy riding it again, I have to sort out those cranks.
I'm only in my 30s, and cycling is my life. If I damage my knees now, I will never forgive myself.
1 comment:
What you discovered is absolutely the last thing I would ever expect. I wonder if even the manufacturers of the respective machines know?
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