oldbobcat

Fore/aft, or setback, is set so that when the torso is in its neutral position, which is usually with the hands on the lever hoods, the center of gravity is over the feet. This facilitates using the back muscles rather than the arms and shoulders to keep to torso elevated.

In practice, keeping the back and the arms share the load, but balancing keeps the arms, upper back, and shoulders from getting fatigued and sore. Balancing also allows the rider to shift easily to standing and pulling up and back on the bars when that's needed.

Torsoes come in different lengths and masses, riders have different back angles and levels of back strength, so this method defies numeric quantification. So far, experience and Steve Hogg's hands-off test are probably the best indicators. And, of course, radical changes in saddle setback can require changes in stem length, which may require a readjustment of setback, which may require . . . So it's an iterative process. At some point the changes in setback become so small that the stem can stay the same.

So what I'm saying is CG is important. To keep the weight off the hands it needs to be over the feet. Runners, skiers, skaters, golfers, tennis players, volleyball players, climbers, skateboarders all keep their CGs over their feet. It's how they keep from falling down. A cyclist can choose between balance or arm strength to keep from falling forward. Guess which is easier?

Road Fan

Sorry, I didn't remember that, but I do know that it's gone around a few times. I don't begrudge the repetition, the newbies or oldbies who will need to know 5 years from now also deserve a good discussion to be able to work out their understanding, just like I did.

Plus as with your point, I learn more by re-learning, if that makes any sense.

Road Fan

My understanding (I don't time trial, but I had a fitter who did) is that for TT and tri-riding you get more power with your body forward. I think it has to do with hip closure angle. Because it requires more core strength if you're going to be in that position for a long time, I find it bad for longer rides where I want to move efficiently but cover several dozen miles with reasonable relaxation and comfort. The reduction in hand pressure is why I like to consider the CG placement in my fitting.

CG like KOPS is not a magic formula. It's means to an end, and it is not the right means for everyone.

I also think the arms are relatively low mass compared to the torso, so you get a lot more reduction in hand pressure by moving the saddle 1 cm back than by moving the hands 1 cm back.

Road Fan

I don't think so, I never had the shoulders, fur, forehead, or the stubby bowed legs. Plus I don't think too many gorillas got engineering degrees.

My dad used to say I was a slim mesomorph. I think now I'm a porky slim mesomorph.

wphamilton

I would say that you set it for the desired hip angle and back position for the type of riding you do, but I'm not a fitter. I'm just talking about the physical mechanics of it.

79pmooney

I used to race. Took it seriously. I would have laughed if you said I needed to be balanced on my seat. Position was all about power, both max and sustained. And wind resistance. I saw to it my back was close to horizontal with a reasonable bend in my arms because if I was going to have to go my fastest, that was what I had to do. And I might need that position for hours. I better have an open hip angle or my breathing/oxygen supply was going to suffer.

Now my approach is to keep very close to that old racing position, the triangle of BB seat and handlebars except that now being aerodynamic is much less important (except on my fix gears) so I rotated that triangle back varying degrees for different bikes. And yes, my CG relative to the BB is different with the different rotations. I buy/have made frames that take that into account. I consider the proper weight balance between the wheels important, quite possibly the difference between staying up and laying the bike down on a hard turn. (I bring a tape measure when I am looking at a new bike. Go home and draw it up on a CAD program and compare it to my existing bikes.)

You might have noticed that my forward positions place real weight on my hands. Yes it does. Fortunately there is a really simple remedy. Train those muscles! There are no drawbacks to having strong enough arms, hands and wrists to ride those positions for hours. I do pay close attention to handlebar and brake lever angles, shapes and positions.

I just noticed the bit about being "balanced" helping out of the saddle riding. Again, this never crossed my mind, ever. And I am a born out of the saddle rider. Go back and forth between the two often.

Ben

bikebreak

I don't race, but had the same experience as you. Moving my seat forward got more power due to being unbalanced - you have to push harder with your legs to balance and take weight off of your hands

Road Fan

79mooney, I think OldBobcat is talking about getting the CG over the BB ("over the feet"), not over the saddle. For me, a forward position from that one is just a few cm of saddle motion.

Doc V

CG should be in relation to BB. This is a concept studied by Keith Bontrager (The Myth of K.O.P.S.). Keith uses a method for determining your CG off the bike that can be translated to the bike and then dialed in after riding. I feel Steve Hogg's method (https://www.stevehoggbikefitting.com...or-road-bikes/) of determining your optimal CG-BB position while actively riding is best since it allows you to determine it as you would be riding on the road, but if you do not have access to a trainer, then Peter White's method (How to Fit a Bicycle) is a good starting point and you can tweak the fore-aft after each ride until you dial it in.

These are all starting points and the final position is dialed over time based on how you feel after a ride. Generally the more forward you are the more power you can generate, but the downside is you may not be able to sustain that position for long periods of time without conditioning.

oldbobcat

Right. I believe Hogg's underlying premise for a balanced position is energy used to maintain position is energy not available for propelling the bike forward. Balance is letting the skeletal structure do more work to maintain position.

In the last few years many pro riders appear to be sitting farther forward than what had been customary. Whether they're on the forward edge of balance, or they are just carrying little mass above the hips, or they have very strong arms and shoulders , or they are outliers, or they've discovered a new fitting paradigm, only they and their coaches know for sure, and so far they're not talking.

due ruote 

I thought wingspan = height was the ideal. At least that's what they taught us in Art History class while you engineer types were crunching numbers. Anyway, it's an interesting discussion.

Voodoo76

I've seen that trend as well, and have played around with it a little. I came to similar conclusions, a typical Pro definitely carries less upper body mass and at the same time is pushing the pedal significantly harder.

Steve's premise is about more than just saving energy and gets to the I think the core of his fitting process. His fitting techniques from the pedals all the way up focus on response from the nervous system. It's a very different process to go through than say Retul which is primarly biomechanical (angles, levers, etc). His theory is that posture and "postural muscles" are given priority by the nervous system. That is we are hard wired to stay upright first and propel ourselves second. So his fore-aft positioning is trying to reduce that postural load on the CNS.

bikeeagle1

If your torso is bending forward (as it is for most cyclists), then something is keeping your torso from toppling forward. That something is either:
1. Weight on your hands
2. Strain in your lower back
3. Some combination of the two.

79pmooney

Wow! This isn't how I got to my position at all. I have heard about KOP for decades but never heard it addressed as anything that mattered by the racers I learned from. I start with the concept of a triangle, pedals (for simplicity the BB), the seat and the handlebars. First order of business: seat distance from the BB. Then it is a matter of finding where my shoulders should be for an effective forward lean to: ensure a good aerodynamic position to go upwind (spiders have their challenges) and an open enough position for good blood flow, etc. Now I swing an arc from my shoulders (on paper, not literally) of radius from shoulder to center of handlebar top. (The working part of that arc is almost a straight line of "slope" of 1 cm steerer height up and 2 cm horizontal stem length forward. Very convenient.) I have now located this line in space X distance forward of the BB and Y height above the BB. I have established the triangle.

Next is to decide what this bike is to do. Cruiser? Rotate this triangle up and back (about the BB) Fix gear that will see wind. Rotate it forward.

The concept of a line for the handlebar position simplifies bike setup a lot, especially for bikes with quill stems. Raising and lowering the quill moves the handlebars at nearly right angles to the handlebar line. Put the HBs on the line and fit is right. Now the bars may be close and low and getting bumped by my knees, or high and for forward (which turns out to be a) sweet for Zzipper fairings and b) a placement I have grown to love; excellent for long days upwind. I do different things on different bikes but my relative shoulder position stays the same. Likewise arm bend.

The end results work for me very well. Yes, my faster bikes place real weight on my hands. Not a problem; physical conditioning works very well here and has no adverse side effects I am aware of. And yes, my weight is well forward of the BB. I chose bikes with short chainstays and longish front ends. Not a problem. And with fatter tires I don't even need the short chainstays. I do choose bikes with steep seat angles to go with those short chainstays, then just use seatposts with a lot of setback.

KOP? I've never looked. As you can see with my rotating triangle, it would vary from bike to bike.

Ben

oldbobcat

Right about upper body mass, for sure. Somehow it went from this


to this


And thanks for clarifying the basis of Hogg's system on the CNS. Point is well taken. I'd been attributing my simplification of it for so long I was forgetting about the difference.

Voodoo76

bikeeagle1, not really. Stand with your heels and butt against a wall, flex your knees, and try to bend foreword from the hips (like you are getting low on a bike). No doubt there is strain on your lower back and you would need to hold onto something to not fall over. Now move your heels just 12"-18" away from the wall, butt still against it and try again. Easy, little strain on lower back & no weight on hands. That's where the hands off test is trying to get you in setback.

Oldbobcat, great pictures! I loved looking at GL on a bike. Especially low on the tops, he was the epitome of relaxed upper body.

McBTC

Note that the pedal position is noticeably more to the midfoot too than current clipless shoes and made to accommodate...

pacificaslim

beautifully explained! Thanks for that.

oldbobcat

Yeah, moving the foot forward on the pedal might play into moving the hips forward over the cranks.

Back in the day, riders were somewhat limited by how much shoe they could fit into their toeclips. I wonder if we never would have been stuck with that "ball of the foot over the pedal spindle" paradigm if Christophe made longer toeclips.

Shoes I'm familiar with that are drilled for more rearward cleat placement are Bont, the Dynalast Shimanos, and Bontrager. One shoe that definitely does not is Pearl Izumi.

McBTC

Still, for anyone that's interested it is pretty easy to use two coupling nuts to extend clips far enough out to accommodate any mid-foot pedal positioning (there's a thread on it).

bikeeagle1

I disagree. The torsional force on your lower back is equal to the weight of your torso plus your head, multiplied by the distance from your sit bones to the CG of your torso (approximately your sternum), multiplied by the sine of your lean angle. Of course, if your torso is vertical (your lean angle is zero), there is no weight on your lower back, it is all on your sit bones. The more you lean forward, the more stress you have on your lower back (or on your hands). This is basic physics involving vector analysis.

I tried your test, and I think that you aren't feeling that torsion because your glutes and legs are activated, but I assure you it is there.

Try this. Assume the position you mention in your post, where you are away from the wall and bending forward. Now, without changing anything else, completely relax your lower back. I promise you your torso will fall forward, until you subconsciously tense your lower back to keep from hurting yourself.