Fit Check: Knee Pain
- Thread starter Terrarium
- Start date
ak-tux
Zen MBB Master
Where is the knee pain, if I may ask? Is it at the front just above the knee cap, or at the out/inner sides e.t.c? Cleat position can also cuase knee discomfort you know.
Hmm, Your knee angle looks like approx 142-145deg (the optimum range is usually between 145 to 155 deg)but the photo may not be completely accurate.
The fit looks good however your toe appears to be pointing slightly forward, right? Probably overreaching unless you are naturally the toe down type of cyclist. Are you able to drop your heel before your leg pulls back in the pedal stoke?
Try shorten the boom by 3 to 5 mm and see how it feels.
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From experience i find a good starting point when stationary is to adjust the boom so the heel of your cycling shoe is just touching the pedal when the pedal is at the dead spot of the pedal stroke. I find having the bike in a stand (or on a trainer) helps. Important as well to be well seated with your hips relaxed and centered on the seat pan.. Boom out to long with have your throwing your hips to complete the pedal stroke, potential pain behind the kneecap, boom too short will result in quad fatigue and pain potentially on the front of the kneecap.
LarryOz
Cruzeum Curator & Sigma Wrangler
If you do this it will make you knee too bend on the backstroke - you really need about 150mm cranks to solve the problem of not being overextended and bent too much
ak-tux
Zen MBB Master
I use an opensource graphics tool called Gimp on Linux to measure the angles. Not the best but it works.
For Windows try
But it all assumes that the camera was perpendicular to the bicycle, otherwise the resulting angles will be skewed .
You still did not mention where exactly your knee pain is.
Anyway, what @LarryOz said about short cranks is also a good idea.
170mm cranks create alot of good torque but for the S40 it restricts how far forward the hands can be extended without the legs hitting the handlebar. At the same time it may create an excessive knee bend at the top of the pedal stroke, which depending on your flexibility may result in some knee and/or hip discomfort. I have ridden my recumbents with 170mm cranks for a long time, indeed, several years now. But recently, knee discomfort has started creeping in.
For the past couple of months I have now been experimenting with some 150mm cranks. And, yes, I have lost some torque. I have compensated with a smaller chainring but I still need some adaptation time. However, for the sake of my knees, I'am patient.
If the knee pain persists and you have eliminated all the possible sources (cleat position, leg extension), you may then also consider some shorter cranks which are fairly affordable nowadays if sourced from AliExpress.
Short cranks will cost you some torque but in return they will reward you with some better fit and happier knees.
Check this thread: https://forum.cruzbike.com/threads/affordable-cruzbike-short-cranks.15531/
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@ak-tux - We're both members of the Cruzbike Linux Users Alliance, breh. Didn't know about the protractor tool though, that's sick.
Knee pain is over the top of knee, between end of quad and knee. It's worse when i KICK out my leg, 100% straight to accelerate. lowering boom has helped alot but i also increased left side q factor with a new pedal. This pedal stroke pictured is not straight, that is to see, my pedal stroke had a kink in it.
Knee pain is over the top of knee, between end of quad and knee. It's worse when i KICK out my leg, 100% straight to accelerate. lowering boom has helped alot but i also increased left side q factor with a new pedal. This pedal stroke pictured is not straight, that is to see, my pedal stroke had a kink in it.
I use an opensource graphics tool called Gimp on Linux to measure the angles. Not the best but it works.
For Windows try
But it all assumes that the camera was perpendicular to the bicycle, otherwise the resulting angles will be skewed .
View attachment 18267
You still did not mention where exactly your knee pain is.
Anyway, what @LarryOz said about short cranks is also a good idea.
170mm cranks create alot of good torque but for the S40 it restricts how far forward the hands can be extended without the legs hitting the handlebar. At the same time it may create an excessive knee bend at the top of the pedal stroke, which depending on your flexibility may result in some knee and/or hip discomfort. I have ridden my recumbents with 170mm cranks for a long time, indeed, several years now. But recently, knee discomfort has started creeping in.
For the past couple of months I have now been experimenting with some 150mm cranks. And, yes, I have lost some torque. I have compensated with a smaller chainring but I still need some adaptation time. However, for the sake of my knees, I'am patient.
If the knee pain persists and you have eliminated all the possible sources (cleat position, leg extension), you may then also consider some shorter cranks which are fairly affordable nowadays if sourced from AliExpress.
Short cranks will cost you some torque but in return they will reward you with some better fit and happier knees.
Check this thread: https://forum.cruzbike.com/threads/affordable-cruzbike-short-cranks.15531/
ok, i see now what you're saying. I always thot maybe i was the exception the rule, thanks for the note.
