Retul or go(niometer) it alone?
Written by: Dan Empfield
Date: Wed Jan 20 2010
Over the last year nothing in the world of tri bike fit has been more written about, and less understood, than the phenomenon of Retul. A triathlete wants, or reports on, or wonders about, a "Retul fit." When that happens I often ask for a description of a Retul fit?
During these moments of appearing the inquisitor to the "Retul fit" inquirer I might note that, boy, it's been awhile since I've had a really tasty "measuring cup" apple pie. This, because Retul is a measuring device, not a fit system. But it would be wrong to simply describe it as this. We sometimes, in our workshops, call Retul a "goniometer on steroids." But this also sells the device short, because there are qualitative benefits that exceed simply a level of precision that a goniometer may not give you.
A Retul will grant you the ability to track metrics that a goniometer does not track. But here's the real question, I think: Does a Retul, in the hands of a master tri bike fitter, result in a better end product—a better fit—than a goniometer? Most of the time, as of this writing, probably not.
But it can, and should, would, and will, deliver a superior fit as these fitters become more accustomed to the relevant features Retul offers. What I can tell you is that a Retul allows me, as a fitter, a chance to observe metrics that I can't observe in any other way.
What I might be talking about, really, is a motion capture system in general, not a Retul system in particular. But I don't have experience with any other motion capture system, so I don't know if Dartfish, for example, produces what I think are a Retul's most relevant and important metrics. So, I'll limit my comments to Retul, noting that Retul may not be the only method to generate specific metrics; rather that Retul bests my goniometer in certain ways I'll note here.
We'll get to those metrics in a minute.
Certainly, the most obvious benefits to a motion capture system, specifically Retul, are, first, the ability to detect metrics generated during a dynamic fit protocol using a dynamic measuring device. What do I mean by that?
I can determine your seat height simply by measuring your inseam. This is a static system for finding saddle height. "Static" because you don't have to pedal a bike, you can just stand there while I measure you. The problem with this system: It requires, or assumes, that you pedal your bike in a specific way. For example, two people who have the same inseam will have different saddle heights if one is a "toe pointer" and one is a "heel dropper." This, because what moves a crank are your hip and lower leg extenders, and your hip angle at top-dead-center, and your knee angle at bottom-dead-center, are really what matter most. These angles describe or inform the advantage your levers will have over the crank.
During these moments of appearing the inquisitor to the "Retul fit" inquirer I might note that, boy, it's been awhile since I've had a really tasty "measuring cup" apple pie. This, because Retul is a measuring device, not a fit system. But it would be wrong to simply describe it as this. We sometimes, in our workshops, call Retul a "goniometer on steroids." But this also sells the device short, because there are qualitative benefits that exceed simply a level of precision that a goniometer may not give you.
A Retul will grant you the ability to track metrics that a goniometer does not track. But here's the real question, I think: Does a Retul, in the hands of a master tri bike fitter, result in a better end product—a better fit—than a goniometer? Most of the time, as of this writing, probably not.
But it can, and should, would, and will, deliver a superior fit as these fitters become more accustomed to the relevant features Retul offers. What I can tell you is that a Retul allows me, as a fitter, a chance to observe metrics that I can't observe in any other way.
What I might be talking about, really, is a motion capture system in general, not a Retul system in particular. But I don't have experience with any other motion capture system, so I don't know if Dartfish, for example, produces what I think are a Retul's most relevant and important metrics. So, I'll limit my comments to Retul, noting that Retul may not be the only method to generate specific metrics; rather that Retul bests my goniometer in certain ways I'll note here.
We'll get to those metrics in a minute.
Certainly, the most obvious benefits to a motion capture system, specifically Retul, are, first, the ability to detect metrics generated during a dynamic fit protocol using a dynamic measuring device. What do I mean by that?
I can determine your seat height simply by measuring your inseam. This is a static system for finding saddle height. "Static" because you don't have to pedal a bike, you can just stand there while I measure you. The problem with this system: It requires, or assumes, that you pedal your bike in a specific way. For example, two people who have the same inseam will have different saddle heights if one is a "toe pointer" and one is a "heel dropper." This, because what moves a crank are your hip and lower leg extenders, and your hip angle at top-dead-center, and your knee angle at bottom-dead-center, are really what matter most. These angles describe or inform the advantage your levers will have over the crank.
This argues for a dynamic measuring system—one that tracks knee angle (and maybe hip angle) through the pedal stroke. But if I use a goniometer (a big protractor that measures the angles of the body), then I have to stop you during the execution of your "dynamic" fit protocol to measure you using a "static" tool.
That makes a goniometer a less precise measuring tool than a Retul. Still, in the hands of a good practitioner, a goniometer can be almost as precise as a Retul. This feature alone is not enough to say that a Retul generates a better fit than a goniometer.
That established, Retul does a very nice job of tracking the knee angle around the pedal circle, and it generates a metric that is harder to measure with a goniometer: knee angle flexion. This is the knee angle at top-dead-center, and this is going to become a more important metric in fitting as practitioners wrestle to get their arms around a truth that attends TT and tri bike fits: crank lengths used by riders are often too long. By looking at knee angles at both the pedal stroke's top and bottom you can assess both saddle height and crank length in tandem.
Then there is the ability of a Retul to capture and store fit data, and to generate norms and stats based on the quantity of data archived. Let's assume that, over time, data is batched by dozens or hundreds of Retul practitioners around the world to a single server. Any of these fitters can see whether the fits he's executing produce a set of metrics that follow or deviate from norms.
This is a slick feature, especially when a light bulb goes on in the brain of a fitter that a specific metric in which he hasn't previously evinced any interest all of a sudden becomes relevant to him. The Retul tracks all these metrics even though the fitter hasn't previously cared about half of them. When he suddenly discovers a metric's importance, he can check Retul's database and see whether all the accumulated data of fitters worldwide produce a result of statistical relevance. In other words, Retuls are now generating the raw materials for inquiries that few if any of us have, as of yet, conceived.
But this also does not mean that, as of today, a Retul produces a better fit in the hands of a good practitioner than a goniometer.
If there is a game changer, it is this: a Retul offers the best method of which I'm aware to measure angles relative to the horizon, which we might call "global" angles as opposed to "rider-centric" angles. What I mean is this: a goniometer measures body angles. And this is important, as far as it goes. But, let's take a case in point: seat angle. One problem encountered during fit sessions is the tendency of some riders to change their saddle positions as their saddles are moved fore and aft. So, if I'm trying to figure out whether I like you better at 79° of seat angle than 78° (and whether you like it better yourself), you may tend to nose-ride 78°, but move back a bit in the saddle when I position you at 79°. Unless I catch you doing this, what just happened is this: I executed two trials at two different seat angles that were, for practical purposes, the same trial—the saddle may have been in a slightly fore or aft position, but you "normalized" for this by sitting in a different place on the saddle.
Here's what a Retul does: A "pick-up" or "lead" on the metatarsal joint of the cycling shoe notes its most forward protrusion during each pedal stroke which, of course, happens when the crank (on the drive side) is at 3 o'clock. Because the foot is attached to the pedal, it can't move. The rider can move fore and aft, but, the pedal can't move. Retul's metatarsal lead can move a little, because the rider's plantar angle changes as he rides more forward (a steep seat angled rider might appear like he's a toe pointer when he really isn't, because his body has been rotated forward around the axis of the bottom bracket).
Nevertheless, that metatarsal lead isn't going to change its position in space very much, but, as the rider moves forward, his knee will certainly change its orientation in space. A Retul notes what is analogous to "knee over pedal spindle," except it's landmarks aren't quite the same as those used in KOPS.
The ability to note when the knee is behind, right over, or in front of the metatarsal is a "global" measure of rider position, instead of a "rider-centric" metric. I can position you at 76° of seat angle, or 80° of seat angle, and all your "rider-centric" angles—your hip angle, knee angle, shoulder angle—might remain the same. There would be no way for me to know, just by looking at these rider-centric angles, where you ride in orientation to the horizon, that is to say, what your seat angle is, or how flat your back is.
But Retul produces two metrics that are global: knee over metatarsal, and the angle of your back (trochanter to acromion) relative to the horizon. This allows a fitter to know, once and for all, whether a rider is actually riding in a steeper position: If I position a rider at 78° of seat angle, then position him again at 79°, only to have that rider self-correct or normalize back to 78° by sitting 1.5cm or so farther back on his saddle, I'll know if I'm using a Retul, because his knee-over-metatarsal distance will not have changed.
Likewise, Retul's readout of a rider's back relative to the horizon is an absolute—global—measure that (all things equal) impacts frontal area. A goniometer does not do this.
That makes a goniometer a less precise measuring tool than a Retul. Still, in the hands of a good practitioner, a goniometer can be almost as precise as a Retul. This feature alone is not enough to say that a Retul generates a better fit than a goniometer.
That established, Retul does a very nice job of tracking the knee angle around the pedal circle, and it generates a metric that is harder to measure with a goniometer: knee angle flexion. This is the knee angle at top-dead-center, and this is going to become a more important metric in fitting as practitioners wrestle to get their arms around a truth that attends TT and tri bike fits: crank lengths used by riders are often too long. By looking at knee angles at both the pedal stroke's top and bottom you can assess both saddle height and crank length in tandem.
Then there is the ability of a Retul to capture and store fit data, and to generate norms and stats based on the quantity of data archived. Let's assume that, over time, data is batched by dozens or hundreds of Retul practitioners around the world to a single server. Any of these fitters can see whether the fits he's executing produce a set of metrics that follow or deviate from norms.
This is a slick feature, especially when a light bulb goes on in the brain of a fitter that a specific metric in which he hasn't previously evinced any interest all of a sudden becomes relevant to him. The Retul tracks all these metrics even though the fitter hasn't previously cared about half of them. When he suddenly discovers a metric's importance, he can check Retul's database and see whether all the accumulated data of fitters worldwide produce a result of statistical relevance. In other words, Retuls are now generating the raw materials for inquiries that few if any of us have, as of yet, conceived.
But this also does not mean that, as of today, a Retul produces a better fit in the hands of a good practitioner than a goniometer.
If there is a game changer, it is this: a Retul offers the best method of which I'm aware to measure angles relative to the horizon, which we might call "global" angles as opposed to "rider-centric" angles. What I mean is this: a goniometer measures body angles. And this is important, as far as it goes. But, let's take a case in point: seat angle. One problem encountered during fit sessions is the tendency of some riders to change their saddle positions as their saddles are moved fore and aft. So, if I'm trying to figure out whether I like you better at 79° of seat angle than 78° (and whether you like it better yourself), you may tend to nose-ride 78°, but move back a bit in the saddle when I position you at 79°. Unless I catch you doing this, what just happened is this: I executed two trials at two different seat angles that were, for practical purposes, the same trial—the saddle may have been in a slightly fore or aft position, but you "normalized" for this by sitting in a different place on the saddle.
Here's what a Retul does: A "pick-up" or "lead" on the metatarsal joint of the cycling shoe notes its most forward protrusion during each pedal stroke which, of course, happens when the crank (on the drive side) is at 3 o'clock. Because the foot is attached to the pedal, it can't move. The rider can move fore and aft, but, the pedal can't move. Retul's metatarsal lead can move a little, because the rider's plantar angle changes as he rides more forward (a steep seat angled rider might appear like he's a toe pointer when he really isn't, because his body has been rotated forward around the axis of the bottom bracket).
Nevertheless, that metatarsal lead isn't going to change its position in space very much, but, as the rider moves forward, his knee will certainly change its orientation in space. A Retul notes what is analogous to "knee over pedal spindle," except it's landmarks aren't quite the same as those used in KOPS.
The ability to note when the knee is behind, right over, or in front of the metatarsal is a "global" measure of rider position, instead of a "rider-centric" metric. I can position you at 76° of seat angle, or 80° of seat angle, and all your "rider-centric" angles—your hip angle, knee angle, shoulder angle—might remain the same. There would be no way for me to know, just by looking at these rider-centric angles, where you ride in orientation to the horizon, that is to say, what your seat angle is, or how flat your back is.
But Retul produces two metrics that are global: knee over metatarsal, and the angle of your back (trochanter to acromion) relative to the horizon. This allows a fitter to know, once and for all, whether a rider is actually riding in a steeper position: If I position a rider at 78° of seat angle, then position him again at 79°, only to have that rider self-correct or normalize back to 78° by sitting 1.5cm or so farther back on his saddle, I'll know if I'm using a Retul, because his knee-over-metatarsal distance will not have changed.
Likewise, Retul's readout of a rider's back relative to the horizon is an absolute—global—measure that (all things equal) impacts frontal area. A goniometer does not do this.
What a Retul does for the clever and intuitive fitter is generate metrics that no one has thought of using before. Hip angle at TDC is a great example. This angle is hard to measure with a goniometer, for a variety of reasons, not the least of which is a difficulty in palpating the greater trochanter at TDC. In any case, this angle is important because there certainly is a minimum usable angle if one wants to still produce optimal power. But fitters have been late to account for this metric. Hip angle flexion, and knee angle flexion, can more easily enter into the lexicon of bike fitting metrics commonly used, as can back angle, because a good motion capture system can "capture" these metrics better than any static measuring instrument.
These metrics are, often, either ignored by our F.I.S.T. Protocol, or, we measure them but use different landmarks. For example, we use the center of the femur/tibia joint line as our knee landmark, Retul uses the lateral condyle. A line from the greater trochanter through the lateral end of the clavicle (the acromion) is what Retul uses to determine the line made by a rider's back; we use trochanter to the convex protrusion of the clavicle.
These sorts of variances in landmarks force one who uses a F.I.S.T. protocol with a Retul system to adjust the rider-centric angles that he hopes to achieve during his fitting process. For example, an included knee angle of 144° using F.I.S.T. landmarks might be 142° using Retul's landmarks. This doesn't change the end product of the fit. It just means that a practitioner trained in F.I.S.T. principles starts looking for 142° instead of 144° if he positions the Retul lead on the lateral condyle. If he decides to keep using the femur-tibia joint line, then, he keeps looking for 144° because, though he's using a Retul, he places the leads according to F.I.S.T. landmarks. The only problem with this is if and when Retul's worldwide library of archived fits becomes relevant—it is only relevant if one set of landmarks is used for every fit, and this is something we, at F.I.S.T., and they at Retul ought to address in the near future.
Note that, for all the above discussion, the Retul is a tool. It's not a system. It's a very powerful tool, and, the use of this tool means that it's easier to look at more angles quickly; to look at angles in flexion more precisely; and, to consider global instead of simply rider-centric angles. And, the plethora of metrics it generates will impact fit systems, that is, F.I.S.T. or any other protocol may morph to take advantage of metrics that Retul generrates.
Nevertheless, Retul remains one of several important tools a fitter ought to have in his arsenal. In my mind, a fitter armed with a Retul, but without a good, adjustable fitting apparatus (a fit bike), is still operating at a huge deficit. It's like a car mechanic owning an expensive diagnostic machine in a service bay that lacks a hoist.
The description here was not designed to be reader-friendly, that is to say, it isn't written to appeal to end-users who lack extensive knowledge of bike fit. If this has all been above your head, not to worry: Below are links to articles that'll get you up to speed. Mostly, this has been designed to explain to practitioners what a Retul will give you that a goniometer won't. But for all readers, I hope for at least one take-away: It isn't a Retul fit versus a F.I.S.T. fit, versus a Serotta or any other type of fit. We demonstrate Retul to every F.I.S.T. Workshop attendee. To consider a Retul fit as distinct from a F.I.S.T. fit is to wonder whether you should be consider open heart surgery, or sphygmomanometer surgery.
A sphygmomanometer, of course, is that device with the cuff you use to measure blood pressure—it's not antithetical to open heart surgery but complementary to it. What bike fit practitioners lack, as of now, is the ability to know with confidence what a Retul system adds to the fit process. Some of the answers are explained above.
But there is that other amorphous Retul feature: the analysis of metrics that matter, but we don't yet know yet that they matter. For this reason Retul is, or will be, the gift that keeps on giving.
These metrics are, often, either ignored by our F.I.S.T. Protocol, or, we measure them but use different landmarks. For example, we use the center of the femur/tibia joint line as our knee landmark, Retul uses the lateral condyle. A line from the greater trochanter through the lateral end of the clavicle (the acromion) is what Retul uses to determine the line made by a rider's back; we use trochanter to the convex protrusion of the clavicle.
These sorts of variances in landmarks force one who uses a F.I.S.T. protocol with a Retul system to adjust the rider-centric angles that he hopes to achieve during his fitting process. For example, an included knee angle of 144° using F.I.S.T. landmarks might be 142° using Retul's landmarks. This doesn't change the end product of the fit. It just means that a practitioner trained in F.I.S.T. principles starts looking for 142° instead of 144° if he positions the Retul lead on the lateral condyle. If he decides to keep using the femur-tibia joint line, then, he keeps looking for 144° because, though he's using a Retul, he places the leads according to F.I.S.T. landmarks. The only problem with this is if and when Retul's worldwide library of archived fits becomes relevant—it is only relevant if one set of landmarks is used for every fit, and this is something we, at F.I.S.T., and they at Retul ought to address in the near future.
Note that, for all the above discussion, the Retul is a tool. It's not a system. It's a very powerful tool, and, the use of this tool means that it's easier to look at more angles quickly; to look at angles in flexion more precisely; and, to consider global instead of simply rider-centric angles. And, the plethora of metrics it generates will impact fit systems, that is, F.I.S.T. or any other protocol may morph to take advantage of metrics that Retul generrates.
Nevertheless, Retul remains one of several important tools a fitter ought to have in his arsenal. In my mind, a fitter armed with a Retul, but without a good, adjustable fitting apparatus (a fit bike), is still operating at a huge deficit. It's like a car mechanic owning an expensive diagnostic machine in a service bay that lacks a hoist.
The description here was not designed to be reader-friendly, that is to say, it isn't written to appeal to end-users who lack extensive knowledge of bike fit. If this has all been above your head, not to worry: Below are links to articles that'll get you up to speed. Mostly, this has been designed to explain to practitioners what a Retul will give you that a goniometer won't. But for all readers, I hope for at least one take-away: It isn't a Retul fit versus a F.I.S.T. fit, versus a Serotta or any other type of fit. We demonstrate Retul to every F.I.S.T. Workshop attendee. To consider a Retul fit as distinct from a F.I.S.T. fit is to wonder whether you should be consider open heart surgery, or sphygmomanometer surgery.
A sphygmomanometer, of course, is that device with the cuff you use to measure blood pressure—it's not antithetical to open heart surgery but complementary to it. What bike fit practitioners lack, as of now, is the ability to know with confidence what a Retul system adds to the fit process. Some of the answers are explained above.
But there is that other amorphous Retul feature: the analysis of metrics that matter, but we don't yet know yet that they matter. For this reason Retul is, or will be, the gift that keeps on giving.
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Comments
CCNS FIT
Reviewed by: Per Vas, Jul 5 2011 6:24AM
CCNS gave me a great bike fit. They worked really well with me and devoted the time to get me felling good on the bike
Bike Fit
Reviewed by: Randy Paar, Jan 24 2010 2:16PM
Great article Dan. I appreciate you exploring the phenom of Retul. After being certified as a FIST bike fitter in April of 2008, and having gone through the Retul fit, I am happier with the FIST method. I've used FIST on 100's of bike fits, and have had great success. Understanding the rider, how and what he rides, is more important then computer generated images! [Editor's note: Thank you for the kind words, Randy! That said, I want to be clear that I find absolute value in Retul and in motion capture in general, but that I think the value is accretive to a proper fit methodology, rather than *instead of* one fit protocol or another. It's not F.I.S.T versus Retul, it's F.I.S.T using Retul versus F.I.S.T. not using Retul. Or some other protocol with or without Retul. That's the sort of decision fitters have to make. Like this: do you want to cut excess aerobar extensions with a tubing cutter or a Sawzall? Your choice of tool doesn't change your notion of the extension's proper length, rather, what tool will give you the best precision?]
Retul
Reviewed by: RC, Jan 22 2010 10:47PM
Great article, Dan. You nailed it. Retul is a great tool for measuring. BUT, the fit still depends on the fitter. I often tell folk that having Retul does not make them a good fitter. Having an MRI machine does not make you a radiologist, right? Retul allows us to measure, dynamically and in 3D precise angles during cycling. I feel the Retul system provides excellent data and I really enjoy using the system. But my fit philosophy for TT and TRI is still primarily based on FIST. I also still use Dartfish. I feel it is useful for client biofeedback on posture and assessment. Retul's "stick figure" is not as helpful for showing a rider different posture positions and start/finish positions during the fit. While Retul allows for the precision, Dartfish is nice for global assessment and feedback.
Dynamic Fit (Retul, Dartfish, etc.) versus Static Fit
Greg Combs (velosmart.com)
Reviewed by: Greg Combs, Jan 21 2010 7:16AM
Dan,
I enjoyed reading this article. You are "spot-on" presenting Retul as a measuring device. I use Retul and Dartfish to measure my client's pedal action and position on the bike under load and even under very little load. It is interesting data to say the least.
Most importantly to me as a fitter I want to help the client not only find their optimum position, but to find asymmetries. Once an asymmetry is identified, what next? For most fitters, this is where a fit system comes into play. However, should a fit system address asymmetries? Maybe... maybe not. Many fitters will use shims, wedges, orthotics and/or corrective footbeds to accomodate an asymmetry. However, I believe in most cases these corrective devices maybe addressing a symptom and not the cause of the asymmetry.
I hope the use of dynamic measuring devices will challenge bike shop owners and fitters to look at ways to help their clients and take bike fitting to another level. Dynamic measuring devices do help with a proper bike fit, but they can also help identify weak links regarding functional leg length problems due to pelvic malalignment and muscle imbalances that impact performance and even cause injury due to instability and lack of mobility of major muscle groups.
The Retul and Dartfish measuring systems are great in finding variances in not only leg angles, ankle and knee tracking, but finding differences in distance between hip joint to elbow and wrist, hip rocking, etc (pelvic shift, weak core, tight hip rotators?). Dan, I am a realist and I believe that many bike shop owners don't have the time, resources, and knowledge to help their customers with range of motion issues, etc. However, shop owners can help in identifying problems and send these customers to fitters, personal trainers, and therapists who are versed in addressing these weak links.
The Retul and Dartfish systems can also and should be used for baseline information for bike fit clients. After the client works on their muscle imbalances through corrective exercises, therapy, etc., they should revisit the bike shop for a followup assessment and remeasure their movement patterns on the bike. With that said, a fitter not using a dynamic measuring device can still help their clients by conducting basic movement screening off the bike and check for malaignments and faulty movement patterns.
From my point of view for the masses (bike shops) should be aware of and knowledgeable in bike fit systems and use these protocols as a guide to helping their clients for a proper bike fit. Once bike shops begin using dynamic measuring devices and find asymmetries, I hope they do the right thing and help their clients find the cause and not address the symptom. Who knows, maybe will will see some of the existing fit systems evolve and create another certification?
As an educator and passionate bike fitter, I would enjoy sharing ideas with other fitters. Dan, thanks for allowing be to add my review of your article. I enjoy your insights and keep these "fitting" articles coming. Your one of the best in this area.
I enjoyed reading this article. You are "spot-on" presenting Retul as a measuring device. I use Retul and Dartfish to measure my client's pedal action and position on the bike under load and even under very little load. It is interesting data to say the least.
Most importantly to me as a fitter I want to help the client not only find their optimum position, but to find asymmetries. Once an asymmetry is identified, what next? For most fitters, this is where a fit system comes into play. However, should a fit system address asymmetries? Maybe... maybe not. Many fitters will use shims, wedges, orthotics and/or corrective footbeds to accomodate an asymmetry. However, I believe in most cases these corrective devices maybe addressing a symptom and not the cause of the asymmetry.
I hope the use of dynamic measuring devices will challenge bike shop owners and fitters to look at ways to help their clients and take bike fitting to another level. Dynamic measuring devices do help with a proper bike fit, but they can also help identify weak links regarding functional leg length problems due to pelvic malalignment and muscle imbalances that impact performance and even cause injury due to instability and lack of mobility of major muscle groups.
The Retul and Dartfish measuring systems are great in finding variances in not only leg angles, ankle and knee tracking, but finding differences in distance between hip joint to elbow and wrist, hip rocking, etc (pelvic shift, weak core, tight hip rotators?). Dan, I am a realist and I believe that many bike shop owners don't have the time, resources, and knowledge to help their customers with range of motion issues, etc. However, shop owners can help in identifying problems and send these customers to fitters, personal trainers, and therapists who are versed in addressing these weak links.
The Retul and Dartfish systems can also and should be used for baseline information for bike fit clients. After the client works on their muscle imbalances through corrective exercises, therapy, etc., they should revisit the bike shop for a followup assessment and remeasure their movement patterns on the bike. With that said, a fitter not using a dynamic measuring device can still help their clients by conducting basic movement screening off the bike and check for malaignments and faulty movement patterns.
From my point of view for the masses (bike shops) should be aware of and knowledgeable in bike fit systems and use these protocols as a guide to helping their clients for a proper bike fit. Once bike shops begin using dynamic measuring devices and find asymmetries, I hope they do the right thing and help their clients find the cause and not address the symptom. Who knows, maybe will will see some of the existing fit systems evolve and create another certification?
As an educator and passionate bike fitter, I would enjoy sharing ideas with other fitters. Dan, thanks for allowing be to add my review of your article. I enjoy your insights and keep these "fitting" articles coming. Your one of the best in this area.
FIST fit using Retul
Reviewed by: Ben Distel, Jan 20 2010 6:25PM
Dan, thanks for the great review. I am not using a Retul (or similar devise) yet but certainly will in the near future. One benefit you do not describe is the ability to constantly see the change in angles while going through the FIST protocol. In addition, i believe that using a Gonio is only as accurate as your ability to precisely locate the Greater Trochanter at every measurement. I have often found that i am either measuring the upper or lower part of the trochanter, with differences in angles as a result. The big question is, how does Retul, using stick-on dots, ensure that the riders shorts are not moving slightly thus giving inconsistent results.
