Our Director of Sports Medicine, Dr. Andy Pruitt, addresses how and why the cockpit is such a critical component to bike fit.
Video Transcript
Dr. Andy Pruitt 00:00
In other Fast Talk Labs videos we’ve discussed saddle position, stance width, and other fit related subjects. In this video, we will explore what is known in the industry as the cockpit or the front end or drop and reach aspect of bike fit. This is one of the most critical aspects of fitting especially as it relates to comfort and biking.
Chris Case 00:30
Welcome to Fast Talk Laboratories, your source for the science of endurance performance.
Bike Posture
Dr. Andy Pruitt 00:41
Nowhere else is the prefit evaluation more important than in the drop in reach. All of historical formulas are not reliable here. These formulas can be used as a starting place. But the final position really depends upon the riders posture and flexibility. word of caution here. If you’re going to pay for a professional bike fit, it should absolutely include a pre fit physical examination. If not save your money until you can find a true professional bike fitter. Today’s discussion is not meant to make each of you a pro bike fitter, it is meant to help you understand why you or your mates may having difficulty with comfort or bike handling. So let’s start with looking at some basic posture and range of motion observations that help drive those front end comfort and handling decisions. So looking at some basic flexibility and range of motions, it really begins with the forward flexion. Some people call this a toe touch but I avoid that because you know our riders are competitive and you say I want you to do a toe touch there by going or to touch their toes. And it doesn’t show you what their true relaxed, forward flexion or Forward Bend might be. So in Chris’s example here, we’ve got a really nice lock leg, which is what we want to have. But it shows me that he’s got a short hamstring component in his whole makeup, because he has a positive upward angle of the back of the pelvis. Right, so the back wall, the pelvis called the sacrum. And if the sacrum were level, then we know he’d had really adequate hamstring length. So this is not the first or last time we’re going to see his hamstring length to come into play. So he stays tight through his lumbar spine, he gets the majority of his forward flexion out of his thoracic spine. And he’s got a big gap between the actual tips of the fingers and the toes. So why do we want to do this, we want the ultimate bike position to reflect the way the athlete really looked right. So I could go back to some historical folks that you might recognize Lance Armstrong had a big hump in his back and, and we tried for years in the early days to get rid of that hump. Well, you can’t get rid of it. Because it is him it was part of his posture. So short hamstrings, tight lumbar spine, a lot of flexibility in the thoracic spine. But it results in this, when you’re when we start to look at him on the bike, he’s going to look like this.
Fitting a bike using Posture
Dr. Andy Pruitt 03:23
So now we turn the view from the back he has not moved, we’ve just moved around behind him. And what I’m looking for would be perfectly a level line across the back. But we don’t see that in Chris actually do we see a little rotation, this side being high. I don’t think this is enough to create an a symmetrical need in the front of his bike, I think this is going to be washed out in a neutral position. However, if this were greater that inclined to that rotation was greater, it could actually end up with a asymmetrical adjustment in the front, usually different brake replacements to take to kind of absorb that rotation, it may, if you don’t make that change in the front end, this rotation may end up showing up on how he sits on the saddle. So cervical posture plays a role here too. In a perfect world, we’d hang a plumb line from the earlobe, and it would fall through the middle of the shoulder. So in Chris’s case, he’s got we call a student’s posture, he’s got his backpack on and he’s hurrying to class. He’s got a little cervical extension, looking out to the front. I think we could call it a cyclist posture as well because we all sit and look up like that, but it was early named as a student posture. So we’re going to probably see some limitations in Chris’s cervical posture as we move forward. So how does that look having him look down. He actually has a gap right there so he doesn’t achieve full forward flexion with a cervical spine, I don’t think this is critical in the cycling position because we’re typically trying to look down the road. But we always assess it anyway. Because if there’s a limitation here, there might be a limitation
Dr. Andy Pruitt 05:16
when he looks up, but I don’t see that I see a really good cervical extension. So he has acquired the ability over his years of cycling, or being able to look down the road, almost regardless of the height of his front end. But you can see where if this were limited, and his visual trajectory, instead of there, or there, the front of the bike is too low that he cannot see down the road. So again, we’re trying to make the bike resemble our riders posture. Okay, here’s the first clue, second clue that his hamstrings are a little short or tight. So if we thought about a 90 degree angle, he’s much shy of that, right? So the typical athletic hamstring length is going to be this would be somewhere in the 65 or 70 degree range, right? He’s less than that. So we’ve got a little hamstring shortness right there. Now, it’s really important to look at both sides, right, so both sides, so both sides of him show up to be less than 70 degrees of straight leg raise less than seven degrees of this angle, which gives me that again, evidence of the short hamstring and his were equal, had they been unequal. That may have explained that slight rotation we saw as he did the forward bend or the forward flexion. But I don’t think that was the case here. I think he just got a little rotation in his spine. So equal hamstring shortness. Here’s where he really makes up for the hamstring inadequacies or shortness, he actually measures 130 degrees of hip flexion. So what he lacks in hamstring length, he really gains back and his ability to flex his hip or bring his knee toward his hip both in combination or how we get around that pedal stroke or that combination of hamstring length and hip flexion is how we get around the top of the pedal stroke. Again, we might check both sides. Absolutely, both sides measure at 130 degrees of hip flexion that compensate for his less than 70 degrees of straight leg raise. So here he is sitting on his bike, we see the same upward angle of the of the sacrum or the back of the pelvis, we see the same tightness in his lumbar spine, we see the same rotation, and his and his thoracic spine. So it’s starting to really create a picture of what his physical exam look like, compared to what he looks like on the bike. second observation, actually, so another way to visualize this is to use a goniometer to set at 90 degrees hip shoulder elbow should create that nice 90 degree and why is this important? So this gives us good architectural strength. Think about a building right so if this were if this were short or long, which we’re gonna talk about in a second, we will start to see changes in his structural stability on the bike his ability to handle it to be able to relax and and steer the bike as well as shoulder obviously and hand pressure discomforts. So second thing to look at what we want is a 15 degree or there abouts elbow bend, that gives us just a little bit of a shock absorber in the front end. Locked elbow is going to give you direct energy from the hand road shock all the way to the shoulder with the elbow, elbow bend would get a little relaxation, we get a little suspension in the front end, can it be greater? I think you’re going to get more fatigue in the triceps. If that elbow bend has to be greater, you’re going to get more shoulder fatigue and shock if the elbow is straighter. Now what happens when the stem gets too short or maybe the saddle is too far forward and we’ve now we’ve lost our 90 degree shoulder and we’ve got this arm of the goniometer behind that angle again so what we’re going to get now is more triceps fatigue this require him to have more cervical extension to look down the road. So again, we want to justify the 90 degree shoulder and The 15 degree elbow bend as a way to stabilize ourselves and both comfortably and handling on the bike.
Results of improper fitting
Dr. Andy Pruitt 10:08
What happens if the stem starts to get too long, right? What happens if the stem starts to get too long, he has, I call this the fishing pole, right? It’s like he’s got a big fish on the pole and the poles all bent and the fish is running away. He’s way out here. He’s trying this is accentuated. This is accentuated, he can’t look down the road as well, because all he’s trying to do is reach those reach those handlebars. That’s what it looks like when starting to get too long. This is really short, this is really high. And you can see now it’s with the combination of short and high. So if you’re home in your garage, and you’re going on, my hands hurt, my back hurts, I think I need to sit up more, right, I need to, I need to sit up more. What happens when we sit up more to a point of diminishing return, we have to jam our shoulders and suddenly you see him turn to shrug up. He’s trying to the bars are too close to him. And he’s trying to get rid of that position by absorbing it in his shoulders. Significant neck fatigue and cervical extension is going to occur with the really short and high position. And it can actually get worse than this. This is a close up of the bars being too far away the cockpit to be in too long, it can be in the saddle too far back. But hopefully earlier in the bike that you’ve established your neutral position have the drive train over the pedals over the bottom bracket and over the saddle. But it can be a saddle too far forward. But mostly this would be a stem too short, or stem too high or some kind of combination thereof. We’ve got a demonstrating the 90 degree shoulder that we’re after his arms are way out in front, we get the big accentuation of the of the thoracic spine called kyphosis, we get this big accentuation or lack of cervical extension forced cervical extensions look down the road with this position. This would be uncomfortable, it looks uncomfortable and it would become uncomfortable for sure. This is a really extreme demonstration of the bars being too high. Now a lot of people think I’ve got to get, I’ve got to get pressure off my hands. So I’m gonna keep bringing that handlebar up and up and up and up. There’s no free lunch from gravity. So if you take weight off your hands, you’re going to put it onto your saddle, got to find this balance between saddle pressure and hand pressure. Again, this time he’s shrugging up, we’ve eliminated the hump and his spine which may look better if you’re looking at just the spine part, but he won’t like it. Because this bike position doesn’t reflect his posture. The bars are up, they’ve they’ve pushed your shoulders back, they’ve eliminated some of his normal curvature and put a significant amount of pressure on the saddle. Not to mention hand pressure. This is long and low right. So this is long ago, he’s really having to reach way down. Now the last time we demonstrated him on the on the on the break hoods. Now he’s in the drops. Some people with a long low position will tell you that they prefer the drops and here’s why. It brings their shoulder closer underneath them. So you’ve made the bike long. Not so low, but long for sure. So instead of having the arm out in front of the shoulder, he’s chosen to be in the drops. To get the shoulder the arm and the shoulder back and better alignment. This is not a sustainable position, but that’s the way they’re going to compensate for that. Starting to get closer right he’s still he’s still very long, but not as low as he was he’s starting to relax a little bit we’ve got the return of his kyphosis This is a little bit more natural in the cervical spine. Alright, now let’s move down to the brake hoods for a second. So if you establish the length of the bike first, right, establish the length of the bike first, now we’ve got an establish how we want to grab the handlebar. And what we want is a neutral handshaking relationship with the bicycle right? That’s what we want. We want a nice neutral handshaking relationship with the brake hood. In the drops, again our goal is a neutral wrist, neutral handshaking position in the drops of the of the handlebars.
Drops, Hoods and Handlebars
Dr. Andy Pruitt 14:43
Now we’re starting to see a bit more wrist extension. Probably because the wrap of the bar is not satisfactory. So typically we have the bars unwrapped, we would let him choose his favorite hand position in the drops. Rotate the bars around to achieve that neutral, neutral hand position right now, I would say that his bars or too rolled up causing wrist extension. Now this looks exaggerated because we didn’t unwrap the bars and the break hoods are way down but there are people who choose mistakenly to have wrist flexion and again not a sustainable position, it will fatigue very rapidly. So our goal again is that neutral position in the drops, bar width you know, as bike fitters there’s a couple things that are difficult to adjust. And we’ve talked about stance with an earlier video and, and how it is difficult to adjust and sometimes it’s kind of overlooked or poo pooed because it’s hard to do. Same thing with handlebars, right? So the bike companies, the manufacturers put the original manufacturing equipment onto bikes using a bell shaped curve of physiatry. Right. So you can be a narrow shouldered slight person who rides a medium or large bike and it’s going to come with 42 or 44 centimeter handlebars which for you and narrow shoulder person, maybe two maybe two narrow, so but changing bars is a hard thing to do but bar width needs to be addressed right? Perfect World. Perfect world plumb line from the outside of the shoulder to the brake hood or to the the arch in the hand. Right? I mean that’s a perfect world. Again, in that perfect world, we’ve got this neutral handshaking position with the wrist and hand on the brake hood. That is so we’re after the line from the outside of the shoulder to the brake hood, arch of the hand. Nice straight neutral, neutral hand position. This tells me the bars are always too wide. That when you want to get your your arm under your shoulder and an architecturally supported place. And when you roll your wrists in to achieve that, it tells me the bars are too wide. It can be a fatigue situation. But typically it’s a bar too wide I’ve seen this in the pro peloton a lot where a rider has chosen a wider bar is given a wider Bar and say here go ride this and they choose to to adjust with the with the folding the wrist in. But this is really a good way to tell you whether or not your bars are too wide, too narrow, you go the other direction, don’t you, you still want to get that arm where it wants to be and relationship to the shoulder. So you’re going to get with you’re going to get with so if you bars are too narrow, this is a way that you would get that now this is a dangerous position, you hit a pothole, this hand and come right off of there at least the other side. The other position is that you’re pretty stable in rough terrain, but not stable in rough terrain when the bars are too narrow. Wow. In the industry today, the trend in mountain bikes is for a really long or wide bar and short stem so if you think about why is a short stem in a long bar. Well if the bars are wide, it creates forward flexion the bars are narrow you come up. So the way you can adjust for this combination is by changing both bar width and stem length. If the if our proper position on the road bike is hands under shoulders, what makes us think that suddenly this big triangulated position is going to be is going to be comfortable. The purpose of the long bar is to give us a lever through technical terrain. So I think before you leave the shop with an uncut mountain bike or straight bar bike, you’ve got to consider the terrain or the experience that you’re going to use that bike on. If you’re going to ride this straight bar bike on bike paths or, or gravel roads and you’re not going to be navigating technical sections. I think you need to adjust the bars as we’re going to discuss actually have a story of a 75 year old woman. avid athlete rides most days hikes. She went and bought a new gravel bike with flat bars and by her
Dr. Andy Pruitt 19:29
by her telling the story she got a complete bike fit. But her handlebars were greater than 80 centimeters wide. She couldn’t ride close to her friends. She’s always out in the road because the bars were so it was a really a dangerous situation not only for from a bike perspective, but from a vulnerable road user perspective. She’s out in the road she can’t ride close she can’t ride double file. Ultimately we convinced her that she did not have a complete bike fit but she went back, got them adjusted, everybody’s happier and everybody’s safer.
Dr. Andy Pruitt 20:04
Okay? Now, when I asked Chris to kind of go to where he’s most comfortable to self select his bar with he’s got at least two centimeters of handlebar sticking out over here so easily we could adjust his mechanics inward, cut off the bar. Instead, he still got enough lever for his technical terrain, but he’s going to achieve that better, that better structural support. We’re looking as always trying to get that neutral support neutral position. If we move everything in again, we’re trying to avoid wrist angulation. So if I asked Chris not to consider not where his mechanics are, but to go where he’s most comfortable, this is his chosen position. So the truth is, his true position is gonna be somewhere between road like and mountain bike like and that I suggest that he cut off two centimeters of each end of his handlebar to achieve that compromise position, he then would have to adjust his stem length, if necessary, that he has his appropriate torso angle, and bar width. Yeah, this is a good example when the bars are really wide, we get this kind of angle drift elbows out now, navigating a steep downhill technical terrain, you might want that leverage for that particular moment again, really think about what your experience is going to be in using this bike, you’ve got to set up for non technical terrain and you encounter a steep technical, you’re safer to get off and walk then try to negotiate that with a short lever. If you’re if you’re encountering those kinds of situations a lot, then you’re gonna want to cheat yourself a little bit wider than the normal road width great lateral shot again we want this nice straight so if we’ve got our bar width and our STEM combination dialed This is going to be the hand position there’s going to be a nice distribution of weight throughout that whole circle hand comfort and risk comfort all the way up the chain. What happens if the stems too long, right, you’re gonna be you’re gonna fall you’re gonna fall in behind it. So again, one of the signs of a stem being too long or the bars being too wide is is you’re going to fall in behind the bar and you’re going to kind of establish this wrist extended position and it is not sustainable. So this is really a sign that your bars are are too narrow or your stem is too short and you’re looking for length the hands out over hands out in front of the bar really dangerous wrist position in that this is not a strong position there’s not much grip, you’re going to bounce off. So not only is it a bad bike position, but it’s a dangerous handling position.
Conclusion
Dr. Andy Pruitt 23:10
This is another way when the bars are too narrow or the stem is too short we’re looking for length and we come out or in front of it, at least we’ve got a good grip of the bar but again, the dynamic forces are going to be coming through the arm and out toward, off the front of the bar again rough terrain you’re going to bounce off and it’s a dangerous place to be so when you’re considering a bike fit the cockpit the front end the drop and reach it you really have to consider the preferred assessment forward flexion demonstration both on the side and from the back. The straight leg raise hip flexion are really key parameters. Now there are many others so if you get a real professional bike fitter, that brief examination is going to be six times more positions than we showed you today but I showed tried to show you just enough so you can start to understand you go home into a straight leg test yourself or to your to your friend. And you might start to explain why his saddle height is wrong or his positions for an aft is wrong or the stems too long. The bars too wide so you really have to make the bike look like the rider my whole entire philosophy of bike fit is that the bike position ends up looking like the rider whether he’s on or off the bike. Hope you’ve enjoyed today. Learn something. We’ll see you next time.
