Seat position / knee pain

[Ben Buitendijk]

Hi all,

First post after a 10 year hiatus from sim racing

I recently upgraded to a P1-X rig, but I am still looking for the perfect seating position and I am getting a bit stuck.

At some point I had some lower pack pain, but it was because I had the pedals too high. Now I have lowered them and that fixed the packpain, but now I have pain in my knee/leg.

I've tried multiple things (angle of the pedals, changing the distance to the seat, putting them extra low with big angle), but they all result in pain, just in a different position :') (sometimes its more the muscle in my calf, sometimes a pain slightly below my knee)

I am wondering about a couple of things:

- How high are your pedal faces (where you apply the pressure) in relation to your hips/back?
- At what angle are the pedals?
- At what angle is your seat?

I bought the seatmount locally, but when I compare the seatmount to simlab's picture, it looks like their max angle is a bit more.
My current angle is around 20°.

Also if I put the pedals lower and I brake really hard, I push myself up, out of the seat a bit... And I guess I should push myself into my seat?

How would different seat mounts/different seat angle affect this?

Thanks in advance,

Ben

 

[Elaphe]

Easy: look for a position in which you feel comfortable and in control of the steering wheel and pedals. Try to place your seat low, not very reclined. Move your seat closer to the steering wheel, never with your arms stretched, but with an angle of almost 90 degrees when holding the rim. That position will guarantee a better control of the steering wheel. The pedals should be higher than on a street car, which will let you apply more force. Try to place the pedal base more or less at the same level of the base of the seat, or a little lower. You will also have to adjust the angle of the pedals and, of course, the distance. Your legs should never be full stretched. Try that there's a bit of angle on your knees when fully depressing your pedals. If you are still experiencing pain, after setting a correct driving position, maybe it would be a good idea to try a different seat. For me, nothing like a tight bucket seat, something in which you get stuck and that will keep your butt and back fixed in position all the time.

 

[blekenbleu]

How would different seat mounts/different seat angle affect this?

Consider remounting the seat backward and positioning the P1X
to test different heights when pushing against some flat vertical surface,
to avoid having to readjust pedals between trials.

I suppose that for max braking
you arrange to have your ankle mostly straightened,
basically as if standing on the balls of your feet,
and modulating pressure thru hip and knee.

Move your P1X and foot around against e.g. a door or wall
to find the most comfortable height and distance,
then recalibrate 100% brake for less than uncomfortable pressure.

After finding the height and distance for that seat angle,
geometry will give pedal heights for different seat angles.

 

[stigs2cousin]

Before suggesting solutions let´s try to find the cause of your knee pain:

as I understand the pain is not in the knee joint (so strike arthrosis and rotation under pressure) and more in calf and shin.

This could mean overexertion of the foot joint with strain on the tendon in the shin.
(because the toes are are "pulled up too much" (sorry, not a native speaker
Or maybe you need muscle tension to keep the foot in place which causes fatigue?


The solution could be to adjust pedal reach and angle so that your leg is completely relaxed when it lightly touches the brake pedal.
The knee should have enough angle that you can push the brake with your thigh muscles, the seat should support your back so that you don´t slide around (and loose power and control in the process)
A lumbar support can aid in stability and protection for your back.

I had similar problems as I tried to model my simrig after my car, didn´t work out at all

So the the pedals went farther away, angle adjusted as above and especially brake and clutch put on a slider.
They are in "normal position" for three pedal driving and for left foot braking the brake wanders to the far left so the leg is straight when pushing (HSV Sprints set to max 65kg´s)
The final touch is small "knee pad" on the left upright of the rig I rest my leg against so I can completely relax between brake applications.

Hope that helps Carsten

 

[Ben Buitendijk]

Thanks guys!

Those are some really good tips Carsten!

Now that you mention it, indeed I felt some fatique to keep my foot in position (like I'm over reaching, even though my legs are still bent). I also feel this slightly in my right leg, which doesn't really apply pressure at all...

I think I have put the pedals too low, when I apply full pressure, it feels like part of the force comes from my knee instead of from my thigh muscles.

I had the pedals higher before and generating power was much easier, but I got a bit of lower back pain... I'm thinking now that that might've been the correct pedal position, but that I need better lumbar support

 

[Bram Hengeveld]

Holy moly @Ben Buitendijk !!! Welcome back!

 

[Ben Buitendijk]

Hey Bram! Long time!!

 

[badbrains7]

I have had the same problem in the past.
It took me a long period of trial and error to solve it.
There are three main things I tried that were related to my knee pain.

1-Distance between seat and pedals
2-Pedal angle.
3-Width between pedals

Probably the numbers themselves don't mean much since each person has a different comfort level.
Basically, the closer the seat and pedals were to each other, the closer the pedals were to a right angle, and the narrower the width between the pedals, the more likely I was to experience knee pain.

I found that a difference of just a few millimeters in distance, width, or angle of 0.5 degrees could cause pain. I think the angle of the pedals is also related to the angle and height of the seat.


As you said, the height of the heel rest can change the pain in the lower back.
In my case, there is a junction point where a 5 mm difference in height causes no pain.


Anyway, you just have to keep adjusting and find the place where you can relax, but I hope you can find a solution.
DeepL Translator

 

[Ben Buitendijk]

Hi all,
I've spend a lot of time experimenting and it's gotten better, but I'm not 100% there yet.

Your tips to raise the pedal plate were really good, I had to add lumbar support, but then I could apply much more pressure way more easily.

I had to play around a bit and I've noticed it's also really important that your ankle is 'locked out'. If its at 90 degree angle or less (toes upward), there is no tension in your knee muscles and it cannot handle the force (I think this was another major issue causing my pain).

So my brake is pretty good now, but now I have an issue with my right leg / throttle pedal xD

The distance where my left leg is comfortable is too far away for my right leg... So at full throttle I'm kind of overreaching (causing fatigue and some discomfort). My pedals have about 2 cm allowance in the mount so I moved it closer, but it's not enough... I've also tried putting it more upright, but it's still not spot on...

Do you guys have any tips/ideas on this?

@stigs2cousin Carsten, how did you mount your brake/clutch? Your solution with a slider sounds great for switching between 2 and 3 pedal modes! Do you have a picture anywhere?

 

[blekenbleu]

Do you guys have any tips/ideas on this?

This literally sounds like the old joke "Doctor, it hurts when I do this." "Don't do that!"

I searched for, but could not find, whether you mentioned which pedals you use,
but it seems that, if at all possible, you should try separately mounting your pedals,
so that throttle and brake can both be at comfortable, but different, distances.
Alternatively, reduce throttle pedal throw,
perhaps adjusting pedal response linearity,
so that initial throttle response is not too abrupt.

 

[Ben Buitendijk]

Stop applying throttle?

The problem is, if I move the pedals closer, my brake is too close... So it's gotta be some other geometrical thing I'm overlooking right now and I hope one of you can help put me on the right path

 

[Elaphe]

Have you tried wearing proper driving shoes? Sometimes the heel of some shoes is designed in a way that makes it hard to press the pedals comfortably and therefore ruins the driving position and can cause pain.

 

[blekenbleu]

some other geometrical thing

What kind of pedals?

 

[Ben Buitendijk]

What kind of pedals?

I use Simtrecs Propedal GT (https://www.simtrecs.com/index.php)

They are mounted directly on the P1X aluminium extrusion plate (so no pedal plate).


I bought cheap shoes, but the sole is pretty soft, so they definitely don't provide much support...

I'll try the Shoe tip aswell, thanks!

 

[stigs2cousin]

@stigs2cousin Carsten, how did you mount your brake/clutch? Your solution with a slider sounds great for switching between 2 and 3 pedal modes! Do you have a picture anywhere?

Hy Ben,
sorry for the late answer, had quite a work filled weekend

My pedals are mounted quite "uniquely":

the accelerator is fixed to the heelplate with two wooden beams.
The heelplate is bolted to the frame via rubber pads and "excited" by an Aura bassschaker.
So I can feel road info through my heels and front wheel vibrations through the pedal.

Brake and clutch are on a second slate of plywood which is also isolated from the frame.
There is a BST-" bassshaker behind the brake pedal for wheel lock / ABS information.
This whole construction slides on the frame rails after loosening four bolts ( for ergononically right direction of the knee when left foot braking versus three pedal driving.)

I can get brake and accelerator at about 3cm distace for ( finally learning) Heel´n´Toe.
( It´s all in the "ok, it works as I wanted it now I only have to find the time to fabricate it properly stage"for about six month now )

In your case my first thought was to put a spacer between pedal face and stem of the accelerator to get the right distance, but that doesn´t seem possible with your beautyfull pedals.

So my solution would be to put the accelerator on a slate of plywood ( it doesn´t need to be extremely stiff because the forces are not that high compared to brake and even clutch) to find the right position to the other pedals.
And when the measurements are finalized I´d have a aluminium plate fabricated that has the bolt holes for the pedals (countersunk from the bottom so that it slides freely on your profiles) with slots for the bolts that connect it to the frame for fine adjustment.

The first plywood iteration would look a lot like the slate my clutch and brake are on.

Good luck and success Carsten

 

[blekenbleu]

Simtrecs Propedal GT (https://www.simtrecs.com/index.php)

Those appear to be very nice pedals; I note slots in pedal mounting "feet":

Depending on how they are mounted on "P1X aluminium extrusion plate":

Supposing that pedal front "feet" are mounted on different extrusion from back "feet",
it should be possible to adjust CP2 so that e.g. brake pedal could be slid back,
so bolts to extrusions are at front of brake pedal "feet" slots, while throttle is slid forward,
so bolts to extrusions for throttle are at back of throttle pedal "feet" slots.

 

[Ben Buitendijk]

Wow I finally seem to have found the right position!!

I'll put the most important points here in case anyone else in the future encounters the same issues:
- Heel plate is at the same height as the bottom of my seatmount (so if you imagine a floor in a car, they are both on the floor).
- My brake pedal is at the maximum angle backwards (15°) and the the throttle I put it a little bit more straight (7,5°).
- The pedals are quite far from the seat and my legs and especially my ankles are almost straightened out. If I put them a centimeter closer, there is a pressure/tension in my knee from 'lifting' my toes, if you feel that, stop and re-adjust!

There were a couple of things I went completely wrong with... I thought if I have knee pain, I should use my thighs more, so I should put the pedals closer to the seat.
And I didn't realise how important your ankles are in relation to your knee... If they are not in the right angle, the muscles in the knee don't support the joint enough and it cant handle the forces

Thanks a lot for your help guys and hope to see you on track soon!