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how important is it...(24 posts)

how important is it...rib-eye
Sep 8, 2001 6:29 AM
that with the crank parallel with the ground, your knee be exactly over the pedal spindle? I've got a new bike and I'm about 1cm behind the darn thing. I've got the saddle as forward as it will go. How much leeway is there in this measurement? The only way I think I can get directly over it is to replace the seatpost with one that doesn't have the clamp slightly set back behind the post itself, e.g. a Thomson.
re: how important is it...Ken2
Sep 8, 2001 7:35 AM
Some people swear by it...Keith Bontrager, mtn. bike guru and bike parts designer, has a rant about "The Myth of KOPS" (Knee Over Pedal Spindle) which I can't seem to find right now.

When you measure, make sure to drop the plumb bob from the bony protuberance below your kneecap, also make sure that your cleats are located correctly and that you aren't dropping or raising the back of the foot differently from when you are riding. And 1 cm is within "tolerance" for all but the most anal....
The K.O.P.S. article is...PsyDoc
Sep 8, 2001 7:44 AM
...available at: http://www.bsn.com/Cycling/articles/kops.html
URL doesn't work nmKen2
Sep 8, 2001 9:48 AM
Try these twoDINOSAUR
Sep 8, 2001 2:03 PM
Here two links: Both have opposing theories on KNOPS

http://www.sheldonbrown.com/kops.html
http://www.cyfacusa.com/frame_fit.htm (scroll down page for pedal spindle setting)
re: how important is it...DINOSAUR
Sep 8, 2001 7:55 AM
Some people swear by it like you said, I'm one of them.
Mine is set about 1cm behind. The KNOP effects which muscles you use in you legs. Your saddle is pushed all the way forward? I had to move my saddle almost all the way to the rear to achieve this setting. What is the angle of your seat tube? Doesn't sound right.
More....DINOSAUR
Sep 8, 2001 9:33 AM
I usually don't read Bicycling Magazine but the July issue had a good article about saddle adjustment.

Saddle 1-2cm back:
More indurance.
Puts most of the demands on pedaling on the back of your legs-some of the strongest muscles in your body. More efficient during downstrokes and when pulling back. Favorable to low cadence pedalers.

Neutral Position:
Knee directly above pedal axel. Spreads pedaling force out over greatest number of muscle groups-decreasing stress on anyone-and lets knee work in it's strongest range of motion.

One CM Forward:
Puts your weight forward for better sprinting. Greatly increases work of the lower-leg muscles and front half of the foot, but hurts endurance-and maybe your knees-which are stuck in their weakest range of motion. Usually best for spinners.

IMHO when I found my perfect saddle and the KNOP setting that worked for me, along with the seat height and angle, I finally felt dialed in with my bike. Of course your bike should fit first in order to achieve all this. It's not one for all, it's a matter of experimenting and finding a setting that works with your anatomy, range of motion, and pedaling style. It's all about fit....
Depends...Rich Clark
Sep 8, 2001 10:16 AM
...in part, I think, on the condition of your knees. I know some young strong triathlete types who move their saddles forward and up to give them more sprinting power. When I do that my knees are killing me 10 miles into the ride.

And keep in mind that as you move the saddle forward you also need to raise it in order to keep your knee extension the same. Height and fore/aft adjustment are interactive, and you always have to do both when dialing in KOP position.

But what effect is this having on reach? Are you having to get a longer stem? Something doesn't sound right here.

RichC
Fit???jtolleson
Sep 8, 2001 10:35 AM
The other question I'm wondering is about your overall bike fit. To be unable to achieve KNOP within the general length of the rails on your seat, seems puzzling to me. Are you sure your bike frame fits you? How is your reach to the bars/brakehoods/drops?

What kind of bike w/how long a top tube? I know this goes beyond what you were asking but what you've described does make me wonder.

Otherwise, I agree with the above posters that you're within the tolerance range, you aren't hurting anything, and some riders prefer the slightly aft position for climbing and cranking.
response to Fit....and a little more info....rib-eye
Sep 8, 2001 4:41 PM
bike - Colnago C40 (60cm, 57.7 tt and 73 degree st)

I went to an LBS to get "properly" measured and sized on a Serotta Fitting cycle before I bought the bike. The guy even looked up in some manual he had; using my measurements and specific geometry of the C40. Supposedly everything was within the norm - me and the bike. Everything else seems to fit/feel just fine. My only concern is the KNOP issue.
oh, one other thing...rib-eye
Sep 8, 2001 4:46 PM
I also used the software sizing facility at wrenchscience.com. It came up with exactly the same frame size for the C40 I was interested in.
Check your cleat position andDog Breath
Sep 8, 2001 10:42 AM
the point at which you are placing the plumb line.
Check your cleat position andrib-eye
Sep 8, 2001 5:58 PM
good point, I did exchange cleats on my road shoes last year and may not have been careful when putting the old ones back on.
Only a starting point.....C-40
Sep 8, 2001 1:43 PM
A great many riders prefer the KOP to be behind the pedal spindle by 1cm or more (me included). Even though I consider myself to be a spinner, setting the KOP directly over the spindle reduces torque and increases cadence too much for me.

It's best if the saddle and post will allow more forward movement for experimentation. The Thomson post will move the nominal saddle position forward by about 2cm. You may also have to purchase a longer stem, if the more forward position suits you.

I had this problem once, when I tried to use an SDG Comp Ti saddle with a Campy post on a Litespeed Ultimate. The wide clamp on the campy post and the rail position of this brand of saddle wouldn't give me enough forward travel.

This problem may indicate that a steeper seat tube angle should be considered for your next frame. The problem has nothing to do with frame size. Some folks get confused and think that a smaller frame will somehow improve this situation. It won't unless the smaller frame has a steeper seat tube angle. The saddle to crank distance is determined by your leg length and remains the same, regardless of the frame size that you select.
proofgrassy knoll
Sep 8, 2001 5:20 PM
i think that the whole kops is a vague theory with little proof to support it. a better guide would be fit and comfort. I ride at least 2cm behind the spindle and can keep up with the best of them. for years i worried about making my body fit some arcane principle and experienced leg pain for my trouble. I am 6'1" and wear size 11 shoes. i suspect like many fit rules that the kops was based on a bunch of 5'5" italian guys riding 1940's bikes. throw out your plumb bob and experiment with your position. when you are fast and pain free you've nailed it. btw check serotta's web site for more info on this
Colnago GeometryDINOSAUR
Sep 8, 2001 5:17 PM
Click onto the VeloNews Tech talk forum, go to page 2 (click on "older messages at bottom of page) Scroll down to "Colnago Geometry" by DaveS. Good post about Nago's. Note mention of Thomson seat post. This might be your problem, you might just need to switch to a different seat post.

Curious as to your inseam length, mine is 34.25 and I'm sized for a 59cm Nago.

I'm considering a Colnago also, but I'm not sure of the fit.
I just might stick with a Klein as I'm aware of their geometry and I know what fits me. Expensive experiment.
Kinda like changing to a Chevy P/U when you've owned three Ford P/U's, and never had a problem with a Ford.
Try the Thompson elitedavidl
Sep 8, 2001 5:32 PM
no-setback seatpost. It worked for me; my brother tried it and it worked for him, too. That and cleat adjustment may just take care of it for you.
Colnago Geometryrib-eye
Sep 8, 2001 5:53 PM
my inseam is 89.5cm (35.25"). I have a longer upper body and long arms so I wanted the longer TT that the 60cm provides over the 59. That exchange in the tech forum was interesting, especially the suggestion on posts and needing as much set back as possible...exactly the opposite of my problem. This is a really curious situation. As I mentioned above, Wrenchscience.com also came up with a 60cm recommended frame as well, although I decided, at least temporarily, to use a 1cm shorter stem (old shoulder/neck issues). I am really confused.

BTW, I have ridden this C40 about 100 miles so far and I am totally smitten by this bike.
more comments....C-40
Sep 9, 2001 5:53 AM
Since you've posted your inseam, I'm curious about how you arrived at the 60cm size. The most common forumla of inseam minus 28cm would have you on a 61 or 62cm frame. The 60cm frame should have a standover height of about 84.5cm, which will give you a generous 5cm standover clearance. This may result in too much height difference between the bars and the stem.

If you have a long upper body and arms, this would suggest that you are quite tall, and would be looking to get the largest frame (and longest top tube) that would be feasible. Seems like a 62cm would have been more appropriate, but it wouldn't make any difference in the saddle position problem, since both sizes have the same seat tube angle.

Now that I know it's a C-40, I also know that you will have a problem getting a 28.0mm post to fit it. A 27.2mm could be used with .015 inch shim stock wrapped around it if necessary.

What type of saddle are you using? Perhaps it's a brand which has the rails set further back than others, or has very limited travel. A different saddle might cure the problem. You might compare your saddle to some other makes at your LBS. Maybe the cure will be a simple matter of finding a different saddle.
more comments....DINOSAUR
Sep 9, 2001 10:00 AM
Good tip about the saddle. I was using a Brooks Team Pro and I had the saddle almost all the way forward in order to achieve my preferred KNOPS. By dumb luck I switched to a San Marco Era and I have the saddle pushed almost all the way back for the same setting. People think of comfort when deciding on a saddle selection, but the position of the rails is probably more important as it effects where you are positioned on your saddle when you have it dialed in.
Good idea, try going to your LBS and measuring the rails. Maybe they could let you try a couple to see if it cures your problem...
Think about.....Tom C
Sep 8, 2001 5:36 PM
how static you are in the saddle. You're not are you? Sometimes you might push yourself back on the saddle to get "behind" the pedal spindle while sitting and climbing.Descending, in a tuck you might be so far forward that you're almost off the tip of the saddle. Time trialing, you might favor a slightly smaller gear to spin instead of lugging and then you will slightly slide up and be "on the rivet". I seriously doubt if you go out and ride your 1cm behind set-up and allow yourself to get used to it that you will find it compromising or unusable. You will optimize yourself through subtle position adjustment.
Think about.....rib-eye
Sep 8, 2001 5:55 PM
good insight. Maybe I'm being to AR about this. It's just that I seem to have the OPPOSITE problem than others have relative to saddle adjustment. Makes me wonder. Thanks.
one more thing...Ken2
Sep 9, 2001 11:04 AM
There's one more piece of the puzzle that's so obvious that no one has mentioned it: are you sure that the saddle height is correct for you? If it's too high that would cause the problem you describe. Even if you have measured your inseam correctly there are other variables, like shoe/pedal/cleat height, that can booger up seat height calculation. Maybe the LBS can check this out too...
Just to complicate things...Jon Billheimer
Sep 9, 2001 3:51 PM
You may have a short femur relative to your lower leg and overall leg length. If that were the case then
you'd require a bike with steep geometry but a relatively long top tube. With respect to the knee over
pedal issue, as mentioned in some posts above, there is no one-rule-fits-all. The neutral position is
simply a starting point. Relative power, torque, foot speed, etc. are heavily influenced by your
particular physical structure and biomechanics.

There's a good custom fit software program at www.bsn.com/cgi-bin/ergobike.egi. Try plugging your
own measurements into it and see if it gives you any further insight into your fit issues.