Knee pain - Crank arm length (E8000)

[tomato paste]

I'm having a bit a knee pain (strangely only on the right knee). Currently running 165mm Shimano E8000 cranks. Anyone familiar with a replacement set that is 155mm and compatible with the E8000?

For the "See a doctor" replies, already done. Had an MRI, nothing is wrong. There is some form of muscular thing going on, maybe flexibility related. The pain is on the outer right side of right knee, with a strange inner pain the crops up after a while, almost feels like the knee is 'locking'--very sharp pain, fast, occurs only on the upstroke near the top of the rotation, and is not a function of exertion--it's actually more frequent when spinning and occurs even if I just leave the right foot on the pedal using only my left leg to drive.

Anyway, I'm going to see if reducing my max flexion helps. I know the E8000 cranks come in 160mm, but thought I'd try 155mm to see what its like. Any replies much appreciated.


EDIT: Shorter Shimano FC-E8000 cranks? - EMTB Forums

 

[flash]

Miranda make 155mm cranks for the e8000 motor.

Having said that, unless you have very short or long legs it's probably not the crank length. No1 culprit would be saddle height. A cm can make a huge difference here. Moving the saddle forward or back might help as well as it changes the effective seat angle and therefore knee movement. And of course, there's foot position on the pedal. Does rotating your foot to a different position on the pedal make a change?

Gordon

 

[Gary]

How tall are you? and what's your inseam?
are you using clips or flats?
And is your saddle height/position correct (at full dropper post extension) while pedalling seated?

With a motor helping to drive your chainring it's all too tempting to pedal with the saddle too low and to low a saddle can cause knee pain/injury

For me anything longer than a 170mm crank on my roadbike causes me knee pain (33" inseam & 5'11" and correct saddle height)

 

[steve_sordy]

Most people do not have perfectly aligned legs.
As a test, do this:

Remove shoes and socks and stand on one leg. Do a deep knee bend and watch where your knee goes. If it tracks in perfect alignment with your foot, and the other knee/foot does the same, then congratulations you are one of the few that have perfect alignment.

If your knee moves off to the left or or the right then that misalignment puts a twisting force on to your knee joint which after a while causes the pain.

You may need some wedges under the ball of your foot to correct the misalignment. They are only needed when cycling. I can't remember which way around the edges need to go, but you don't need much. Anywhere between 1-3mm is usually enough. In my early days of biking, I used to have severe knee pain after 16 miles, followed by days of hobbling about. Then I discovered the Specialized BG (body geometry) wedges that came with some insoles I had bought. That solved my problem! Unfortunately Speccy don't sell the wedges and the insoles separately anymore, only with shoes they sell. (Smart move by Speccy, as selling separately was allowing their tech to enable me to buy other brands of shoe). I still have those wedges, must be coming up to 20 years now and still working!

 

[tomato paste]

I'm 188cm height (6'2") on a spectral on XL with flats, inseam is 83cm. I adjust my saddle height to have max flex with the heel of my foot on the pedal at the low pedal position. From there, I've adjusted up and down 5-10mm, and I've tried moving the seat fore and aft. Doesn't help. I've also tried fiddling about with my foot in various positions on the pedal while biking, but once the pain has begun, foot position doesn't subside the pain.

I thought it may be the wide Q-factor, as I've never had any issues with my road or city bike. Or, as it's a used bike, if the right crank arm may be slightly bent from a rock strike? It definitely has something to do with the knee alignment, I can feel some rotational movement in the knee that I haven't ever noticed on another bike. With feet planted flat and parallel, my knees are rotated inward. Alternatively it's an aging thing, I've played sports and maintained fitness until my 30's, but entering my 40's things are stiffening up.

This the wedge your thinking of? Cyclestore.co.uk

For the Miranda Delta SH, I'm guessing Q:16 (standard) is the appropriate Q-factor for the E8000, but wanted to double check.

 

[steve_sordy]

Yep! Those are they! Brilliant find, I can get some new ones now.

PS: I use two of the 1.5mm wedges in each shoe. Once you have read up on it, you will see that it is VERY important to get the correct type, varus or valgus.

 

[nickfrog]

Try an entire ride without lowering the saddle and see if the pain still occur.

 

[flash]

I'm 188cm height (6'2") on a spectral on XL with flats, inseam is 83cm. I adjust my saddle height to have max flex with the heel of my foot on the pedal at the low pedal position. From there, I've adjusted up and down 5-10mm, and I've tried moving the seat fore and aft. Doesn't help. I've also tried fiddling about with my foot in various positions on the pedal while biking, but once the pain has begun, foot position doesn't subside the pain.

I thought it may be the wide Q-factor, as I've never had any issues with my road or city bike. Or, as it's a used bike, if the right crank arm may be slightly bent from a rock strike? It definitely has something to do with the knee alignment, I can feel some rotational movement in the knee that I haven't ever noticed on another bike. With feet planted flat and parallel, my knees are rotated inward. Alternatively it's an aging thing, I've played sports and maintained fitness until my 30's, but entering my 40's things are stiffening up.

This the wedge your thinking of? Cyclestore.co.uk


View attachment 40197



For the Miranda Delta SH, I'm guessing Q:16 (standard) is the appropriate Q-factor for the E8000, but wanted to double check.

View attachment 40198

That's what I got. BTW, I do ride 155's on my e160. Not because of sore knees. More for rock strikes. I like them.

Gordon

 

[Cavi]

i alsoo run the 155s but honestly with your height I do not believe that is your issue. I am only 5'10 with a 28 inch inseam, and on analog bikes I run 170mm. I am with the others, seat heaght, and inclination

 

[R120]

I would be surprised if its to do with the crank arm length - if anything going with a shorter crank may make it worse - I know from a previous life riding a bit of track and a lot of fixed gears that shorter cranks tend to not help with the knees, I know its a bit different with EBikes but you are still going to be putting more strain through the joint with a shorter crank. Also the Q factor on the E8000 isn't far off a standard BB.

However knee pain is often a symptom/manifestation of a problem elsewhere:

I’m a physiotherapist, bike fitter and racer, and this is your definitive guide to knee pain and cycling

Nicole Oh guides you through the most common injury experienced by cyclists

www.cyclingweekly.com

 

[Calsun]

I would check the length of your legs. Not unusual for one leg to be sufficiently shorter to cause problems and this can be fixed at the pedal or with the bike shoes. Usually the pain is in the hips but it could affect the knees as well. In general knee pain is the result of having the seat too low or using too high a gear when going up hills.

 

[tomato paste]

I would check the length of your legs. Not unusual for one leg to be sufficiently shorter to cause problems and this can be fixed at the pedal or with the bike shoes. Usually the pain is in the hips but it could affect the knees as well. In general knee pain is the result of having the seat too low or using too high a gear when going up hills.

Generally I think this is an accurate description. After replacing my saddle, stretching the hips more, and spending less time sitting, the knee pain disappeared.

Apparently there is a connection between the hips and the knees, such that when one sits for prolonged periods of time, the connective tissue within the hips can shorten/stiffen (in particular the Psoas), which leads to pain within the knees. Sit less, stretch and move more. The pain was not related to a particular component of the bike, but rather the rider.

 

[Gary]

PS: I use two of the 1.5mm wedges in each shoe. Once you have read up on it, you will see that it is VERY important to get the correct type, varus or valgus.

or just stop using 5:10s and be able to alter your foot position at will

 

[steve_sordy]

or just stop using 5:10s and be able to alter your foot position at will

I last wore 510's in 2012 and I have been able to move my foot at will ever since.

I started using those Specialized wedges about 20 years ago, they stopped my knee pain. That was long before I was into mtb and have been using them ever since. Once I bought an mtb, I soon moved from trainers and plastic pedals to SPDs and some Bontrager SPD shoes (still got them). That lasted about 18 months before swapping to flats and 510s. They had great grip, but too much for my taste. In addition they were as waterproof as a sponge, weighed a ton when wet and took ages to dry out. So I switched to Shimano AM flats and Kona WahWah pedals. Those pedals are long gone, but I've stuck with the Shimano AMs ever since. I've almost worn out my second pair and I have a third new pair in the cupboard. The grip is great and yet I can still shuffle my foot about if needed.

 

[Gary]

Ah... ok... my mistake. Appologies.
Shimano AMs are actually too stiff for my liking. It's definitely not for everyone but I find a more flexible (skate) shoe (and not tightly laced) on flats way better for knee ankle and foot pain/injury. I have dodgy knees too and my left foot was completely rebuilt 19 years back. I'm actually meant to wear an insole wedge prescribed by physio all the time, even to just walk. But I don't. My foot is pretty strong now mainly from riding. I still if at all possible try not to walk any long distance though as it leaves me in a lot of pain. especially if uphill. Whereas I can ride all day pain free.

If you're going to wear a wedge I'd recommend seeing a professional first rather than taking "Steve off the internet's" 1.5mm (vernier verified) recommendation.
You could end up doing more damage than good if you get it wrong.

 

[steve_sordy]

.................

If you're going to wear a wedge I'd recommend seeing a professional first rather than taking "Steve off the internet's" 1.5mm (vernier verified) recommendation.
You could end up doing more damage than good if you get it wrong.

You don't have to accept "Steve's off the internet recommendation" because the instructions that come with the box are very good. You don't even have to buy anything to check if you have misalignment; read below. The wedges I bought were from Specialized's BG range (Body Geometry).

You start by removing shoes and socks and stand on one leg, then do a deep knee bend. Watch where your knee goes in relation to your foot. If the knee tracks in line with the foot, then congratulations you have no misalignment of the knee joint. But many, many people have misalignment. They can can track left or right or in different directions to each other, or even only one knee. Then you start by adding one shim (marked 1,5mm varus or valgus) and repeat the knee bend. Keep adding shims until each knee tracks straight. Dead simple to do and it had an astonishing impact upon me. Previously I could not ride much more than 16 miles on the road before I got really bad pain in both knees that would take days to go. Afterwards I rode 84 miles in two days along tarmac and towpaths - no knee pain.

 

[Gary]

Yeah... Specialized are very very good at marketing.

 

[steve_sordy]

Yeah... Specialized are very very good at marketing.

They were not that good at marketing! I bought their BG footbeds (still using them 20 years later), but the wedges were not mentioned nor even pictured on the box.
However, whether they are good at marketing or not, those BG wedges worked.

 

[Gary]

Guess what? Specialized did not invent orthopedic insoles.

 

[steve_sordy]

Guess what? Specialized did not invent orthopaedic insoles.

Who knew? They must be good at marketing after all!

 

[JoeBlow]

Some years ago I had a similar pain. I felt sure it was a joint or cartilage issue but it only came on when I walked downhill. After a couple of years of tolerating this a good physio told me to stretch my hamstring muscle regularly by putting my heel on a table and bending my head towards my toes. After a week or so doing this exercise the problem was solved and I have never had it since. He suggested that it was due to an imbalance between the muscle at the front which was well developed because I was a rock climber and the muscle at the back.

Al

 

[Mikerb]

on a similar theme roadies tend to develop their quads and unless managed that tends to shorten/tighten the hamstrings. Pulled hamstrings then becomes a common injury if playing sports such as football or tennis.

 

[RustyIron]

Here's your physiology lesson for the day, and just in time for Halloween!

 

[peterwalk]

It is best to ask an experienced professional about it. Because if you suddenly make a choice yourself, there's a good chance you'll be wasting your money. When I had problems with my tendons, I went to Cameron Orthopaedics - Cameron Memorial Community Hospital and for a good reason. The doctor who treated me was a very experienced specialist. He recommended I get all possible medical tests. In addition to my tendon problems, he found several non-serious diseases. I cured everything without difficulty in the early stages

 

[Mikerb]

It is best to ask an experienced professional about it. Because if you suddenly make a choice yourself, there's a good chance you'll be wasting your money. When I had problems with my tendons, I went to Cameron Orthopaedics - Cameron Memorial Community Hospital and for a good reason. The doctor who treated me was a very experienced specialist. He recommended I get all possible medical tests. In addition to my tendon problems, he found several non-serious diseases. I cured everything without difficulty in the early stages

sounds like the usual response from the garage mechanic when you just want the headlight changed!!