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Old 06-19-07, 02:27 PM   #1
George
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Knee over pedal

I've been playing around with this knee over pedal thing for quite a while now and I can't seem to get it. I've read Peter White's overview on the subject and I've read Andy Pruitt's as well. Peter says it doesn't make any difference, and Andy says it does. Is it just a starting point and when you find your comfort zone, just stay there? If it's that you need your knee cap over the end off the end of the crankarm I'll have to buy a setback seatpost. It just seems to me, if I can go a pretty good distance, should I change anything or not. I was looking at the point of the power output you can put out with your knee as far back as you can get it as well. Thanks for any replys.
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Old 06-19-07, 04:58 PM   #2
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IMO you should have the axis of your knee directly above the axle. Thus the point of the kneecap would be about 1.5-2" ahead of the axle. They talk about moving back for power but I find sitting too far back for long is uncomfortable. I'll move about 4" fore and aft in the saddle, depending on the situation and how sore my butt is.

Working toward good posture is laudable, but don't get all anal retentive about it.
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Old 06-19-07, 06:03 PM   #3
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Quote:
Originally Posted by George
I've been playing around with this knee over pedal thing for quite a while now and I can't seem to get it. I've read Peter White's overview on the subject and I've read Andy Pruitt's as well. Peter says it doesn't make any difference, and Andy says it does. Is it just a starting point and when you find your comfort zone, just stay there? If it's that you need your knee cap over the end off the end of the crankarm I'll have to buy a setback seatpost. It just seems to me, if I can go a pretty good distance, should I change anything or not. I was looking at the point of the power output you can put out with your knee as far back as you can get it as well. Thanks for any replys.
I experimented with Peter's concepts for a while. I had my saddle back so I was in balance over teh crank when tucked into the drops with a flat-feeling back. My knees indicated about 2 cm behind the spindle. My hands found their natural height and I placed the bars in that position, and hand pressure went away. I could easily "float" over the saddle and 'bars on rough pavement, just like back in high school! On a few of my frames I had to search out seat posts with extra setback. I found American Classics and CLB from Wallbike to be real suitable. Then my knees started hurting in front!

I went to a fitter here in town, and he set me based on watching me after I warmed up, my knee ended up at KOPS, and set up the saddle height by measuring my knee angle and setting it at 30 degrees. Now as long as I don't mash, my knees are super and power is actually better. I don't know what it takes to make Peter's philosophy work, but I don't have it. Three weeks later I still like what the fitter did!

If I didn't have any pain I would not have gone ot a fitter and changed my posiiton.

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Old 06-19-07, 06:11 PM   #4
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Thanks for the replys guys. The problem I have is, I can't raise the saddle any higher, and the bump just below the knee is over the spindle now. If I raise the saddle any higher my leg will be completely extended. Thanks again.
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Old 06-19-07, 07:24 PM   #5
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Rules are always general, but each body is specific in its strengths, needs, and resources. Absolute rules are never absolute for everybody....only an idealized version of all of us, but hardly always true for each of us (whatever the heck that means!).

I find that I move forewards and backwards on the saddle just for variety and to relieve specific pressure points-- as do we all. Right there I've just thrown off the absolute KOPS: my below the knee bony protuberance thingy is pushed or pulled off KOP. Not to mention, a static position invites overuse or sooner onset tiredness. Small angle adjutments can be refreshing.

George, don't be slavish to rules of fit... they're just guidelines. Experiment for what seems to work best...i.e. avoids pain, seems most efficient for you, and is most comfortable. Keep in mind that Peter White has fairly severe arthritis in his back.
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Old 06-19-07, 07:27 PM   #6
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I've read both articles you reference and Peter White's makes the most sense to me. His argument are just quite believable. I too struggled with finding the right position and now believe that the knee over the pedal spindle is indeed a starting point. From what you describe, I'm wondering what your crank arm length is. If you remember Mr. White was pretty clear that crank arm length needs to be determined, and will have an impact on fore-aft saddle adjustments. The first time I read his article, I know I skimmed over this portion of it and pretty much ignored it. After months of trying to get the fore-aft thing right, I went back to the crank arm length section and ultimately determined that I need a length of 170, not the 175s I already had. I made the switch on just one of my bikes, and the difference was considerable and positive. As I can find replacments crank arms, I'm going to make the change on all of my bikes. Hence, I belive Mr. White's system is a good one, but you can't be selective in which parts to follow and which to ignore. Good luck with your efforts.
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Old 06-19-07, 08:13 PM   #7
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Thanks again, and yes I did understand what you said CC and that's what I was kind of thinking. I'm not hurting so I guess I should just leave it alone. I just keep thinking, if I do this, or that, I may pick up more power. I do push it sometimes and get a hint of knee pain, but I know it's me, I think. Sometimes when I get done riding I don't feel I pushed it that much and have a little pain, and that's what had me thinking of more saddle back. I will check out the Peter White article again and read about the cranks. I know they are 175s, but by having a large frame, I thought that the cranks and the bike cranks, would go hand and hand. Anyhow I'm going to go reading, thanks again.
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Old 06-21-07, 09:13 AM   #8
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Originally Posted by George
Thanks for the replys guys. The problem I have is, I can't raise the saddle any higher, and the bump just below the knee is over the spindle now. If I raise the saddle any higher my leg will be completely extended. Thanks again.
George, you generall try to move your saddle forward or back to get the knee positioned, not up or down. There's still a knee angle criterion, (typically the knee should be bent 25 to 30 degrees with your leg at full extension and clipped in) that has to be in the right ballpark, and it is set by raising the saddle. If you have the seat in the middle of its rails and you set teh height, then slide it to get knee position and level the saddle, you should always recheckthe saddle height afterwards. You might have to iterate back and forth a few times before both criteria are met the way you'd like them.

If you can't move your saddle back far enough, thre are several options:

1. Some saddles have longer rails thatn others, and the Brooks/ are among the shortest!

2. Some seatposts have more offset than others, you might have to hunt down a different seatpost

3. The frame might not be a good fit for you. The seat tube angle controls how far back the seat is wrt the BB, in addition to teh seatpost offset and the saddle rail position. If you have real long femurs, you could need a special configuration, or at least differeent from what you have.

But you seemed to be saying you would set teh knee position by raising/lowering teh saddle, and that is not the main adjustment for knee, and knee is not the real purpose of having adjustable saddle height. You're not doing it right, if I understood you correctly.

Hope this helps you!

Road Fan

ps: BTW, setting my knee angle and knee postion together made a world of difference to my riding and comfort.
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Old 06-21-07, 09:40 AM   #9
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Quote:
Originally Posted by George
I will check out the Peter White article again and read about the cranks. I know they are 175s, but by having a large frame, I thought that the cranks and the bike cranks, would go hand and hand. Anyhow I'm going to go reading, thanks again.
Typically anyone using a frame of 19" (hybrid & mountain) or 56cm & up are better fit with 175mm cranks.

The "crank arm algorithm" that I've seen says to take the length of your inseam and multiply it by 5.48 to find the recommended length of your crank arm in mm. I think this is a bit conservative. But in using it, anyone with an inseam of over 31.5" should be using 175mm cranks. A lot of people will calculate out to 180+, but I don't think that option is available. And I should be using 155-160mm!
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Old 06-21-07, 11:40 AM   #10
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Originally Posted by Road Fan
George, you generall try to move your saddle forward or back to get the knee positioned, not up or down. There's still a knee angle criterion, (typically the knee should be bent 25 to 30 degrees with your leg at full extension and clipped in) that has to be in the right ballpark, and it is set by raising the saddle. If you have the seat in the middle of its rails and you set teh height, then slide it to get knee position and level the saddle, you should always recheckthe saddle height afterwards. You might have to iterate back and forth a few times before both criteria are met the way you'd like them.

If you can't move your saddle back far enough, thre are several options:

1. Some saddles have longer rails thatn others, and the Brooks/ are among the shortest!

2. Some seatposts have more offset than others, you might have to hunt down a different seatpost

3. The frame might not be a good fit for you. The seat tube angle controls how far back the seat is wrt the BB, in addition to teh seatpost offset and the saddle rail position. If you have real long femurs, you could need a special configuration, or at least differeent from what you have.

But you seemed to be saying you would set teh knee position by raising/lowering teh saddle, and that is not the main adjustment for knee, and knee is not the real purpose of having adjustable saddle height. You're not doing it right, if I understood you correctly.

Hope this helps you!

Road Fan

ps: BTW, setting my knee angle and knee postion together made a world of difference to my riding and comfort.


Thanks for the help and suggestions. I couldn't move the saddle back any farther so I had to go up. I couldn't go up anymore and my knee was still about 2" in front of the spindle of the pedal. It was either, get a setback seatpost, or a new saddle with more setback ( longer rails), so, Will suggested to try the Serfas saddle. I read that last night, and right after I read it, went and bought one. After a 25 mile ride this morning, no more knee pain. I wasn't in a lot of pain, but it was really holding me back from getting into a bigger gear and pushing harder. For the most part, most of my rides are 20 or 25 miles anyhow, so it should work out, I hope anyhow. On my ride this morning, I didn't even think about the saddle or my knees, and that alone was a welcome relief. Anyhow thanks everybody for all the help.
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