Pelvis rotation

[dekindy]

Does whether your pelvis is neutral, tilted forward, or tilted backward impact bicycle frame design or do builders even take this into consideration?

[Hawker]

Not sure about the specific answer to your question, but a lot has been written about pelvis rotation. I have some back issues from an accident when I was a teen. I've tried to adjust my pelvis rotation but find it impossible to maintain without concentrating the entire ride...which is impossible. It's as if someone told you to ride with one elbow sticking out as far as you can, it would never feel natural and your body would never find that to be a default position.

I'm prepared to be corrected though.

[thinpin]

Not sure about the specific answer to your question, but a lot has been written about pelvis rotation. I have some back issues from an accident when I was a teen. I've tried to adjust my pelvis rotation but find it impossible to maintain without concentrating the entire ride...which is impossible. It's as if someone told you to ride with one elbow sticking out as far as you can, it would never feel natural and your body would never find that to be a default position.

I'm prepared to be corrected though.
Pretty much my experience too.

[dekindy]

I have been told by a trainer that my pelvis tilts, cannot remember which direction, but she says hers tilts in the opposite direction of mine. Apparently it is easy for a trainer to tell just by observation. She says it is nothing you can change. Just wondered if that was entirely handled by your saddle or whether the steepness of the seat tube angle would compensate if that is taken into consideration in the design or could make it worse if not taken into consideration?

[sevencyclist]

My builders never palpated my pelvis for rotation. I need a re-do!

No seriously, there's so much minute variation with saddle, post setback, hill angle, condition, that I doubt this will be a factor that could be built into the equation.

The fact is that when a singlespeed changes cog size, the chainstay length changes, and yet no one is screaming that the wheelbase length change throws the whole bike handling characteristics off.

[akelman]

Ed Sullivan wants you to read only the top of this thread.

[Ti Designs]

Does whether your pelvis is neutral, tilted forward, or tilted backward impact bicycle frame design or do builders even take this into consideration?

I'm a little lost here. Are you saying that you would go to a frame builder without an established position and without having ever seen you riding the bike on the road, and you would have them do a fitting and build a custom bike from that?

[dekindy]

I'm a little lost here. Are you saying that you would go to a frame builder without an established position and without having ever seen you riding the bike on the road, and you would have them do a fitting and build a custom bike from that?

I have no idea how you got to this but I will try another way.

All other measurements being equal, would whether a rider had a tilted forward or backward or neutral pelvis be considered in the frame design?

[Fishbike]

Ed Sullivan wants you to read only the top of this thread.

Too late. . .Elvis has left the building.

Elvis should have spent more time on the bike in those later years. Although we have recently learned he had more in common with pro cyclists that you would have thought.

Good one, Akelman!

[Ti Designs]

All other measurements being equal, would whether a rider had a tilted forward or backward or neutral pelvis be considered in the frame design?

Yes, pelvic tilt is a key parameter in fit (as well as saddle selection). That along with lower back flexability is the reason all of the measurment based fitting systems fail so badly, so often. Back when I was selling Seven bikes, they had this system where the fitter would take all sorts of measurments, then send them over to Seven and they would design the perfect bike for the customer. I added another step, I set up the Size Cycle (it's OK, we took the Serotta decals off one side and put on Seven decals) by the numbers they came up with and more often than not found that it didn't fit as well as it should have.

[rustychisel]

more often than not found that it didn't fit as well as it should have.


the supplementary question - put coarsely - must be: 'so how d'ya fix it? Fix the rider or fix the bike design'?

After all, thinking about it coarsely, everything flows from giving good pelvis: comfort, power, stability.

[dave thompson]

I have been told by a trainer that my pelvis tilts, cannot remember which direction, but she says hers tilts in the opposite direction of mine. Apparently it is easy for a trainer to tell just by observation. She says it is nothing you can change. Just wondered if that was entirely handled by your saddle or whether the steepness of the seat tube angle would compensate if that is taken into consideration in the design or could make it worse if not taken into consideration?

Sounds like a match made in heaven!:eek:

[sevencyclist]

I'm a little lost here. Are you saying that you would go to a frame builder without an established position and without having ever seen you riding the bike on the road, and you would have them do a fitting and build a custom bike from that?

Hi Ti, I know you feel strongly about having the fitter actually see the rider on the bike, preferably on the road. However, many respected members in this world of custom bike building, including names like Strong, Weigle, Kirk, Sachs, Seven, Serotta build most of the "custom" bikes without such process. Spectrum has a little more lore of the "barn ride" like you suggested.

I think it is too hard to expect that a builder would build specifically for one and only one saddle, and the bike would not fit anymore if somehow the customer changed the saddle. I have had three custom bikes built for me, and it took me quite a while to realize that fit is not a permanent fixed event, and the bike just needs to be built to within a range of adjustment to achieve proper fit. A great builder is able to make a bike that will handle "right" when the rider is within that range of "proper fit."

I was sold on the "one perfect position" idea when I started out with my first custom bike Seven, but have since evolved through many adjustments and two additional custom bikes, so now enjoy riding without thinking about whether I am in that "perfect position" or whether the bike is built "right".

In this same vein, that is why I think the bike dimension needs to be close enough, so the variation of pelvic tilt, saddles, and posts could be accommodated while the bike still fits and handles right.

[mtechnica]

Unless you're flexible and have a good amount of drop, as well as a proper fitting bike with a good saddle position, it's probably not going to feel natural to ride in the pelvis rotated position. IMO it's just something that comes with fitness and enough miles, you can't force it or fake it. So if you go to a framebuilder you'll probably get whatever you're starting at unless they change your fit a lot which is unlikely.

[LO^OK]

Yes, pelvic tilt is a key parameter in fit (as well as saddle selection). That along with lower back flexability is the reason all of the measurment based fitting systems fail so badly, so often. Back when I was selling Seven bikes, they had this system where the fitter would take all sorts of measurments, then send them over to Seven and they would design the perfect bike for the customer. I added another step, I set up the Size Cycle (it's OK, we took the Serotta decals off one side and put on Seven decals) by the numbers they came up with and more often than not found that it didn't fit as well as it should have.

Not to derail the thread but the reason for this failure is probably because all fitting systems have too narrow an outlook in attempting to fix a position that cannot be fixed because it is contrary to to human physique and the anatomy of movement. Our lower limbs haven't evolved to operate with a fixed pelvis and lower spine. All locomotion, and the other sports in particular (walking, running, swimming, skiing) engage the pelvis and the spine, used for the balancing and stabilisation of the body. This balancing/stabilisation act which involve tensioning of muscles groups is important for the prevention of injuries; on contrary, joint injuries happen easily when postural muscles are relaxed. This road cycling fixation on fixing the pelvis is very likely central to the inefficiency (because it limits the muscle groups engaged), and to the injuries of the knee and hip joints, and the lower spine.

[Hawker]

Ed Sullivan wants you to read only the top of this thread.

LOL....I think you have to be a certain age to remember that. Unfortunately...I do.

[Ti Designs]

Hi Ti, I know you feel strongly about having the fitter actually see the rider on the bike, preferably on the road. However, many respected members in this world of custom bike building, including names like Strong, Weigle, Kirk, Sachs, Seven, Serotta build most of the "custom" bikes without such process.

This is what baffles me. When you say "respected members", you are talking about frame builders, not fitters. Yet so many people here feel that the frame builder is the authority on fit - why? How does skill with a torch make one an expert on fitting? When hardlyrob was in the process of ordering his Kirk he came to me, we made some changes, did a little riding, made a few other small changes. The geometry that Dave built had been tested and tweeked before he started to miter tubes - seems like the smart way of going about it... Seven is just a few miles from my shop, they opened the Ride Studio Cafe just down the road from me. While we're no longer a Seven dealer, from time to time I get a customer in who wants a Seven, but has other fit issues that Seven can't solve, so I wind up fitting and selling a Seven. I see a fair number of Sevens on the road, many of them look like the fitting was done in a dark room. As a fitter it hurts just knowing how much they paid and how poorly it fits, but I also know that nobody from Seven is ever going to ride with them, so neither Seven nor the customer will ever know. If you're going to suck at your job, a lack of feedback is a good thing... As for Serotta, I thin Stan Mavis wanted to put a hit on me 'cause he sold a number of demo bikes to customers of mine, while they were a smokin deal, they didn't fit, so I sent 'em back. In the balance between good fit and making money, good fit lost that one. Even before things at Serotta went south, back when Mr Bedford was drafting the build sheets, the handling of the bikes would reflect Kelley's rather laid back tastes. When I ordered my Serotta it was a direct copy of my two Peter Mooney race bikes. He argued that the bike would be too stiff and too fast for anything but perfectly smooth roads. That's the bike I used for D2R2 this year.

My point in this is that the builder builds bikes. The fitter fits bikes, and I would hope that before someone goes and plunks down the deposit on a custom bike, the rider knows how they ride.






I think it is too hard to expect that a builder would build specifically for one and only one saddle, and the bike would not fit anymore if somehow the customer changed the saddle.

A bike is built around a position, not a saddle. Pelvic tilt has a lot to do with which saddle you wind up on. I've mostly used two saddles in my life, the Concor and the Aliente - they're pretty much the same saddle. The tail of both saddles flairs up, which works with my forward pelvic tilt. Those riders who can hinge at L5/S1 and L4/L5 can use a flatter saddle like the Toupe.

[jpw]

The problem with fit is that the fit machine isn't really being dynamically ridden. The pedals turn but that's not replicating true body movement when on an actual bike out on the road.

[11.4]

Let's take this a step further.

First, many riders will say they only feel comfortable in a position that looks, frankly, awful.

Second, some riders want to ride like Cancellara or Pantani or whomever and try to emulate something that is neither appropriate nor even comfortable. One sees those too.

Third, framebuilders are the real recipients of the hard knocks school of bike fit. If your bike doesn't fit, you don't blame the stem or your own back. You blame the framebuilder. And realistically, a boutique framebuilder who relies on someone else for a fit is both giving away part of his expertise and product offering and also has an uncontrollable variable inserted in the process.

Fourth, there are different philosophies of frame fit. There are those who emphasize aerodynamics, or power, or comfort, or some look that they grew up believing in, or whatever. Is one better than the other? Not clear. Remember that professional road cyclists often go through some pretty significant makeovers when they go through wind tunnel testing or change coaches.

Fifth, your own position can change, and often quite dramatically, even within the course of a season. Flexibility, strength, weight, etc. all contribute to substantial changes in position. Just trying to ride 25 mph versus 20 will change your position on the bike.

On and on ...

The point is that fit is a dynamic issue.

[Ti Designs]

some riders want to ride like Cancellara or Pantani or whomever and try to emulate something that is neither appropriate nor even comfortable.

Yeh, much like fasting before doing a blood test, I ask that my customers give up the bike porn for a few weeks before the fitting. Having a mirror in the fit studio also helps...

framebuilders are the real recipients of the hard knocks school of bike fit. If your bike doesn't fit, you don't blame the stem or your own back. You blame the framebuilder. And realistically, a boutique framebuilder who relies on someone else for a fit is both giving away part of his expertise and product offering and also has an uncontrollable variable inserted in the process.

If I'm doing the fitting and sending the builder the numbers, I would expect the builder to at least know who I am. Newer fitters should probably stick to making changes on stock bikes until they really know what they're doing. This goes against the teaching theory of most fit schools, they think two days of exucation on fitting is enough to risk the customer's money. But then, how many fitters stay in the business that long?


there are different philosophies of frame fit. There are those who emphasize aerodynamics, or power, or comfort, or some look that they grew up believing in, or whatever. Is one better than the other? Not clear. Remember that professional road cyclists often go through some pretty significant makeovers when they go through wind tunnel testing or change coaches.

Yet another reason not to rush into custom geometry. I had raced for 5 years before I bought my first custom. In that time my position had evolved and I had a severe back injury, and then it evolved some more. In the last 25 years, from my first custom Peter Mooney to my current Serotta, my frame geometry hasn't changed. I run a higher stem position in the winter/early spring and a lower one in season.

As for the trade-offs between comfort and power, is it too much to ask for both? Really, a more powerful position isn't less comfortable and a more comfortable position isn't less powerful. That concept was started by people who don't understand riding position, they push harder to try to generate more power, and that to them is uncomfortable. Kinda like saying my car's gas mileage sucks at full throttle...


The point is that fit is a dynamic issue.

And yet there are a lot of people out there making a living from doing really expensive fits and telling their clients that they are in the perfect position. Well, they're not all out there...

[sevencyclist]

This is what baffles me. When you say "respected members", you are talking about frame builders, not fitters. Yet so many people here feel that the frame builder is the authority on fit - why? How does skill with a torch make one an expert on fitting? When hardlyrob was in the process of ordering his Kirk he came to me, we made some changes, did a little riding, made a few other small changes. The geometry that Dave built had been tested and tweeked before he started to miter tubes - seems like the smart way of going about it... Seven is just a few miles from my shop, they opened the Ride Studio Cafe just down the road from me. While we're no longer a Seven dealer, from time to time I get a customer in who wants a Seven, but has other fit issues that Seven can't solve, so I wind up fitting and selling a Seven. I see a fair number of Sevens on the road, many of them look like the fitting was done in a dark room. As a fitter it hurts just knowing how much they paid and how poorly it fits, but I also know that nobody from Seven is ever going to ride with them, so neither Seven nor the customer will ever know. If you're going to suck at your job, a lack of feedback is a good thing... As for Serotta, I thin Stan Mavis wanted to put a hit on me 'cause he sold a number of demo bikes to customers of mine, while they were a smokin deal, they didn't fit, so I sent 'em back. In the balance between good fit and making money, good fit lost that one. Even before things at Serotta went south, back when Mr Bedford was drafting the build sheets, the handling of the bikes would reflect Kelley's rather laid back tastes. When I ordered my Serotta it was a direct copy of my two Peter Mooney race bikes. He argued that the bike would be too stiff and too fast for anything but perfectly smooth roads. That's the bike I used for D2R2 this year.

My point in this is that the builder builds bikes. The fitter fits bikes, and I would hope that before someone goes and plunks down the deposit on a custom bike, the rider knows how they ride.








A bike is built around a position, not a saddle. Pelvic tilt has a lot to do with which saddle you wind up on. I've mostly used two saddles in my life, the Concor and the Aliente - they're pretty much the same saddle. The tail of both saddles flairs up, which works with my forward pelvic tilt. Those riders who can hinge at L5/S1 and L4/L5 can use a flatter saddle like the Toupe.
Thanks Ti. I agree with you that fit is something in addition to where the bike tubes are joined. I had fitting done with a fitter to make my bike truly mine on my custom bikes. I see your point that a cyclist should have a fitter work with the rider to identify that position and give that position to the builder to miter the tube around it.

My point is that the "perfect position" is a dynamic thing, so a good builder is someone who can join the tubes to not only fit the current position, but anticipate that position to evolve a little and still be with good characterisitis in handling and ride. So some of these respected members are ones who can put that current fit into the middle of the adjustment range, so shifts in different directions still maintain the flavor of the builder's preference in their design.

My answer to the OP would be that the pelvic rotation is something that, while important, the adjustment needed to compensate for the variation is too small to affect the overall dimension of the bike, so adjustment comes in forms of finding the right stem, right saddle, and right saddle post setback rather than altering design of the whole bike. So this is something the fitter is involved, but probably not necessary at the level of frame builder.

[dekindy]

My answer to the OP would be that the pelvic rotation is something that, while important, the adjustment needed to compensate for the variation is too small to affect the overall dimension of the bike, so adjustment comes in forms of finding the right stem, right saddle, and right saddle post setback rather than altering design of the whole bike. So this is something the fitter is involved, but probably not necessary at the level of frame builder.

This is what I was looking for. Does everybody agree with this?

[CromoSapien]

While we're on the subject, there's been a similar concern over the fit of the French teenager Alizée since she sang for the opening of the Tour de France in 2003.

Based on this kind of rotation, can she be fit by the numbers, or would she require a personal fit session?

http://www.youtube.com/watch?v=ot-DD1oQE78 .

:)

[mtechnica]

This is what I was looking for. Does everybody agree with this?

Disagree because even if the contact points are the same, a frame builder is left to determine the resulting geometry and weight balance. I doubt a frame builder would build the same frame for an out of shape person as they would for the same person a few years down the road that now has an aggressive fit (lots of setback, drop, and reach) for example so no, if your position isn't where you want it and you have a bike built for you it's very possible that if/when you do get the position sorted you won't be happy with the bike for any number of reasons. That's not to say it can never work but I doubt you'd end up with a bike that handles and rides as well as it could.

[pdmtong]

This is what I was looking for. Does everybody agree with this?

we can all adapt to slight variance given the initial range is right. so, yes, i agree. combine sevencyclist and tidesign comments and thats that

[rustychisel]

While we're on the subject, there's been a similar concern over the fit of the French teenager Alizée since she sang for the opening of the Tour de France in 2003.

Based on this kind of rotation, can she be fit by the numbers, or would she require a personal fit session?

http://www.youtube.com/watch?v=ot-DD1oQE78 .

:)

Heck of a first post, fella.

First time I saw her I thought 'I don't need no stinkin' podium girl'.

[11.4]

To get right to the point, which was hip rotation, it's perhaps the one dimension that changes bike position more than any other. If you maintain a lot of curvature in your lower back, you'll be creating in your hips the saddle setback you'd otherwise pursue in your frame design. You'll pull your knees backwards, so the rules about KOPS (which I don't buy anyway) are thrown out. Your leg length effectively changes. Your saddle angle likely needs to change. You will change the angle of your back and how low your back can get, so you change reach to your bars, etc.

I do actually find that riders can compensate for hip rotation at either extreme by the position they take on the saddle. And riders can acclimatize to a different level of hip rotation in many cases; it takes a lot of effort but is worth it.

Hip rotation can change dramatically the amount of power a rider can put out. If you just want to gear down, you don't have to worry about it. If you want to ride fast and climb fast, it's something to address. And when you do a bike fit, someone does have to see the hip rotation to know what role it plays and also how much it can be altered. A remote fit by a framebuilder can give a good fit based on my current ride and in particular, based on my current level of hip rotation. But it won't take into account how my hip rotation changes when putting out more power, or how much I can change my hip rotation with training, or how much the rest of my position compensates for awkward hip rotation.

Why is this the case? Your thigh muscles and hip muscles act very differently. The hip muscles (glutes and related fibers) have a different intra-muscular structure and different contraction geometries that in combination allow them to put out much more power than your quads ever can. What they can't do, however, is contract in rapid repetition for an extended period of time. That's what your thigh muscles are for -- they have much less power but they can contract much faster and at much faster rates of repetition. So if you need power -- a standing start, the beginning of a sprint, a steep climb -- you want to position your hips so you're using your glutes more. Then when your cadence goes high and you need to accelerate through high cadences (the finish of a sprint, or riding on the flats), you use your hips less and your quads more. You naturally do this -- you get out of the saddle for the efforts requiring more power and less cadence. This isn't to hold your bars better. It's because you are effectively changing your hip rotation temporarily to maximize the power of your hips. In reality you rarely get that efficient about it, but the real advantage of doing dead lifts, squats, etc. in the gym is that you train yourself to use your hips properly. And you can have a tremendous improvement from learning how to use your hips. It's still about hip rotation.

[etu]

great thread!

are there any good pictures on the web to illustrate these concepts?

[soulspinner]

I excersize my back, seems to help me maintain a longer time in the drops with my pelvis tilted.............

[LO^OK]

Hip rotation can change dramatically the amount of power a rider can put out

Your thigh muscles and hip muscles act very differently. The hip muscles (glutes and related fibers) have a different intra-muscular structure and different contraction geometries that in combination allow them to put out much more power than your quads ever can. What they can't do, however, is contract in rapid repetition for an extended period of time. That's what your thigh muscles are for -- they have much less power but they can contract much faster and at much faster rates of repetition. So if you need power -- a standing start, the beginning of a sprint, a steep climb -- you want to position your hips so you're using your glutes more. Then when your cadence goes high and you need to accelerate through high cadences (the finish of a sprint, or riding on the flats), you use your hips less and your quads more. You naturally do this -- you get out of the saddle for the efforts requiring more power and less cadence. This isn't to hold your bars better. It's because you are effectively changing your hip rotation temporarily to maximize the power of your hips. In reality you rarely get that efficient about it, but the real advantage of doing dead lifts, squats, etc. in the gym is that you train yourself to use your hips properly. And you can have a tremendous improvement from learning how to use your hips. It's still about hip rotation.

I am afraid both of these statements are incorrect. More than one peer-reviewed studies found out hip rotation effect on power generation to be negligible; to cite the study linked bellow, the effect was "less than 3%" on the power generated.

https://docs.google.com/viewer?a=v&q=cache:rIGukuZHIHcJ:www.me.utexas.edu/~neptune/Papers/jab26(4).pdf+journal+of+Sports+et+sciences,+1997,+ 15,+395-402&hl=en&pid=bl&srcid=ADGEESjYViEy_VZcTEJHbdwQ9qKNRHFMGrtamspkuFUH l2uoGDBOeIuF1UXiW5VOkKMd5M-1nLHxSMknYjUr_LAkHwDEHWC_GENwYLb-R1Leort2FBFBwYFZE2pT33HtkU6SvbDfjPva&sig=AHIEtbTidyrkBv5FT0SYjGBOkFw3isAZuw

As regarding the thigh muscles and hip muscles acting "very differently" due to the hip muscles supposedly "different intra-muscular structure and different contraction geometries", both the gluteus and the vastus groups of muscles have the same feather-type muscular organisation, geared towards power generation at the expense of reduced range of motion and speed. The more power generated by the gluteus muscles can be explained by it's larger cross sectional area, and not because fundamental differences in structure. Same apply to the speed of contractility, i.e. it is the same as there is no morphological or physiological basis for such a difference. I stand to be corrected though and am curious to see citations to the contrary.

http://books.google.be/books?id=WuWKRc2jZ5AC&pg=PA66&lpg=PA66&dq=quadriceps+femoris+penniform+or+fusiform%3F&source=bl&ots=eBa0OaWOQ6&sig=s19ab7AohCUwpTqD1O7THF2hIVg&hl=en&sa=X&ei=PLSTUP2xCsqp0QX_roGYAQ&redir_esc=y#v=onepage&q=quadriceps%20femoris%20penniform%20or%20fusiform %3F&f=false

http://books.google.be/books?id=PCKxhwL1sSQC&pg=PA40&lpg=PA40&dq=gluteus+maximus+fibre+arrangement&source=bl&ots=UsYEvsdEI9&sig=eRyD_W7Tk5zcRzJ8UzHkO8aVqEI&hl=en&sa=X&ei=w6-TUPmnDYat0QW-1YGIDw&redir_esc=y#v=onepage&q=gluteus%20maximus%20fibre%20arrangement&f=false

[11.4]

I am afraid both of these statements are incorrect. More than one peer-reviewed studies found out hip rotation effect on power generation to be negligible; to cite the study linked bellow, the effect was "less than 3%" on the power generated.

https://docs.google.com/viewer?a=v&q=cache:rIGukuZHIHcJ:www.me.utexas.edu/~neptune/Papers/jab26(4).pdf+journal+of+Sports+et+sciences,+1997,+ 15,+395-402&hl=en&pid=bl&srcid=ADGEESjYViEy_VZcTEJHbdwQ9qKNRHFMGrtamspkuFUH l2uoGDBOeIuF1UXiW5VOkKMd5M-1nLHxSMknYjUr_LAkHwDEHWC_GENwYLb-R1Leort2FBFBwYFZE2pT33HtkU6SvbDfjPva&sig=AHIEtbTidyrkBv5FT0SYjGBOkFw3isAZuw

As regarding the thigh muscles and hip muscles acting "very differently" due to the hip muscles supposedly "different intra-muscular structure and different contraction geometries", both the gluteus and the vastus groups of muscles have the same feather-type muscular organisation, geared towards power generation at the expense of reduced range of motion and speed. The more power generated by the gluteus muscles can be explained by it's larger cross sectional area, and not because fundamental differences in structure. Same apply to the speed of contractility, i.e. it is the same as there is no morphological or physiological basis for such a difference. I stand to be corrected though and am curious to see citations to the contrary.

http://books.google.be/books?id=WuWKRc2jZ5AC&pg=PA66&lpg=PA66&dq=quadriceps+femoris+penniform+or+fusiform%3F&source=bl&ots=eBa0OaWOQ6&sig=s19ab7AohCUwpTqD1O7THF2hIVg&hl=en&sa=X&ei=PLSTUP2xCsqp0QX_roGYAQ&redir_esc=y#v=onepage&q=quadriceps%20femoris%20penniform%20or%20fusiform %3F&f=false

http://books.google.be/books?id=PCKxhwL1sSQC&pg=PA40&lpg=PA40&dq=gluteus+maximus+fibre+arrangement&source=bl&ots=UsYEvsdEI9&sig=eRyD_W7Tk5zcRzJ8UzHkO8aVqEI&hl=en&sa=X&ei=w6-TUPmnDYat0QW-1YGIDw&redir_esc=y#v=onepage&q=gluteus%20maximus%20fibre%20arrangement&f=false

Actually, that article has several failings. First, it is a computer model of a leg rather than an actual athlete. Such models sometimes work, sometimes don't. Second, it isolates the leg and hip from the rest of the body, so it doesn't address the full-body kinesiology that has been demonstrated many times to be critical to analyzing lower leg performance. Third, the results are in the minority. The authors cite several papers who demonstrate much more significant results than theirs, but fail to relate exactly why their own testing should give such nominal results. Fourth, both British Cycling and the Australian Institute of Sport have done extensive testing on riders on bikes with both remote and implanted telemetry and used those as a basis for their bike positioning and equipment design. Both groups, with larger budgets and with actual competition results as proof of their actual efficacy, concluded that hip rotation was quite important. Fifth, this article acknowledges that muscle retraining can result in more significant results, which is the point of much of this thread. And sixth, this article delved only slightly into hip rotation and was focused mostly on the parameter of seat tube angle. The article basically cut off half of the hip rotation by isolating only the lower extremity.

As for the comment about muscle types, I was keeping my description of muscle structure very general so the forum would fully grasp the significance of the points, which weren't about experimental protocol but about real life performance. In fact, the muscles of the gluteus maximus and medius have a shorter range of contraction but, because the muscle has a larger relative cross section, it has more individual contractions to enlist. This is the same thing that I said above.

These comments came in particular from studies done on world-class trained cyclists at the Australian Institute of Sport. Theirs were the first studies done with extensive implants, full telemetry, actual power readings, and laser positional analysis. If you get authorization and a password you can get onto their restricted sites and read their studies -- these are made available to all their technical partners and to AIS-accredited coaches.

I appreciate your clarifying my language a bit, but please understand that I was trying to avoid throwing Pubmed and other citations at riders who just want to understand how things work. You'll need a better citation than that one to convince anybody that hip rotation is not significant in riding efficacy and power.

[Joachim]

TWhen I ordered my Serotta it was a direct copy of my two Peter Mooney race bikes. He argued that the bike would be too stiff and too fast for anything but perfectly smooth roads. That's the bike I used for D2R2 this year.



So I can come for a fit and order my Peter Mooney at the same time?

[Ti Designs]

Having used 8 sheets of paper to print out that study so I could read it over 20 - 30 times to fully grasp what it said, I have come to two conclusions. First, I've wasted a few sheets of paper. Second, the people at the journal of applied biomechanics do very little actual application - in other words, in this case they don't ride bikes.

The model in this case has nothing above the SI joint, the pelvis is held in place. This may work in the case of the vastus muscles as the forward force at the pedal also anchors the pelvis in it's seated position, but can someone remind me where the upper attachment point is for the glutes? Are they saying that the mass of the body above the pelvis is zero - if so I think they're taking this weight loss thing a bit too far. And let's talk about the two large muscle groups and their ability to generate RPMs, as the whole test was performed at 90 PRM. Again, the quads are the easy case, force at the pedal can be calculated based on contraction of the muscle and the model used. The glutes leverage the rider's upper body weight, gravity comes into the picture. If the acceleration of the pedal is greater than that of gravity it doesn't work.

It is a very nice model of how nobody pedals a bike...

[LO^OK]

Actually, that article has several failings. First, it is a computer model of a leg rather than an actual athlete. Such models sometimes work, sometimes don't. Second, it isolates the leg and hip from the rest of the body, so it doesn't address the full-body kinesiology that has been demonstrated many times to be critical to analyzing lower leg performance. Third, the results are in the minority. The authors cite several papers who demonstrate much more significant results than theirs, but fail to relate exactly why their own testing should give such nominal results. Fourth, both British Cycling and the Australian Institute of Sport have done extensive testing on riders on bikes with both remote and implanted telemetry and used those as a basis for their bike positioning and equipment design. Both groups, with larger budgets and with actual competition results as proof of their actual efficacy, concluded that hip rotation was quite important. Fifth, this article acknowledges that muscle retraining can result in more significant results, which is the point of much of this thread. And sixth, this article delved only slightly into hip rotation and was focused mostly on the parameter of seat tube angle. The article basically cut off half of the hip rotation by isolating only the lower extremity.

These comments came in particular from studies done on world-class trained cyclists at the Australian Institute of Sport. Theirs were the first studies done with extensive implants, full telemetry, actual power readings, and laser positional analysis.

Could you point me to any of the studies you mention online (and no restricted access and passwords please)?

[jimcav]

What did you mean by "maintain a lot of curvature" are you talking about lumbar flexion or extension? I'd think extension would pull the pelvis and knees back on the bike, where as flexion the opposite--flexion would seem more likely as you are leaning forward to the bars?

I have mid-back pain, chronic, from anterior wedge compression fractures at T7-8 in Jan 2011. Literally yesterday the doctor (a DO) said yes, that area is tight, but my lower back is "locked up tight"--i never have had pain in lower back or feel discomfort there riding. He said my hips and SI joint movement are good.

I am chasing my tail on bike fit and comfort--perhaps the pain i get in the hip flexor and deep buttock is really somehow caused by the tight lower back (but it is only left side for the hip--my surgery side, now 10 months ago)?

thanks
jim

To get right to the point, which was hip rotation, it's perhaps the one dimension that changes bike position more than any other. If you maintain a lot of curvature in your lower back, you'll be creating in your hips the saddle setback you'd otherwise pursue in your frame design. You'll pull your knees backwards, so the rules about KOPS (which I don't buy anyway) are thrown out. Your leg length effectively changes. Your saddle angle likely needs to change. You will change the angle of your back and how low your back can get, so you change reach to your bars, etc.

I do actually find that riders can compensate for hip rotation at either extreme by the position they take on the saddle. And riders can acclimatize to a different level of hip rotation in many cases; it takes a lot of effort but is worth it.

Hip rotation can change dramatically the amount of power a rider can put out. If you just want to gear down, you don't have to worry about it. If you want to ride fast and climb fast, it's something to address. And when you do a bike fit, someone does have to see the hip rotation to know what role it plays and also how much it can be altered. A remote fit by a framebuilder can give a good fit based on my current ride and in particular, based on my current level of hip rotation. But it won't take into account how my hip rotation changes when putting out more power, or how much I can change my hip rotation with training, or how much the rest of my position compensates for awkward hip rotation.

Why is this the case? Your thigh muscles and hip muscles act very differently. The hip muscles (glutes and related fibers) have a different intra-muscular structure and different contraction geometries that in combination allow them to put out much more power than your quads ever can. What they can't do, however, is contract in rapid repetition for an extended period of time. That's what your thigh muscles are for -- they have much less power but they can contract much faster and at much faster rates of repetition. So if you need power -- a standing start, the beginning of a sprint, a steep climb -- you want to position your hips so you're using your glutes more. Then when your cadence goes high and you need to accelerate through high cadences (the finish of a sprint, or riding on the flats), you use your hips less and your quads more. You naturally do this -- you get out of the saddle for the efforts requiring more power and less cadence. This isn't to hold your bars better. It's because you are effectively changing your hip rotation temporarily to maximize the power of your hips. In reality you rarely get that efficient about it, but the real advantage of doing dead lifts, squats, etc. in the gym is that you train yourself to use your hips properly. And you can have a tremendous improvement from learning how to use your hips. It's still about hip rotation.