 So welcome back, or I should also be saying welcome to the ninth edition of the RCA training tip show where every Wednesday Aussie time I'm going to be your YouTube Road Cycling Coach and host of the show, Cam Nichols. So getting a good proper bike fit, possibly one of the most important things you can do if you want to take your road cycling performance to the next level. So in today's video using me as the subject matter, we are going to be pinpointing some common bike fitting corrections that may lead to dramatic improvements in speed, power and aerodynamics purely from a good bike fit. Now, as many of you will know by now, I recently took the BMC team machine SLR01 down to Brisbane here in Queensland, Australia to get a comprehensive bike fit with Neil Stambry, who has a sports physio background and has been fitting road cyclists here in Australia for around 10 years. Now, Neil's already made some big changes to my fit, which you're going to see in this video today. And I can say that they have already positively impacted my cycling, but the biggest change, I believe, is yet to come. And I've just recently ordered these through my local bike shop, and that is after 11 years of road cycling for the first time ever, I'm going to be changing on the BMC team machine the crank length from 172.5 to 165. That's quite a significant 7.5 mil difference. And what's interesting in 11 years of road cycling, I've had numerous bike fits never before has anyone recommended that I change the length of my crank. Yet what you're going to hear in today's discussion is Neil's argument is compelling about why I should change after all these years and I am now sold. So there will be a part two to this video today where I can share with you my experiences transitioning from 172.5 to 165 mil crank length. Now, before we get into this video, I just wanted to let you know that this is only 30% of my discussion with Neil. So what I thought, because the whole discussion is actually quite interesting, we're going to go off tempo on the channel tomorrow. I'm going to publish the full discussion with Neil for anyone out there interested, which is a full 27 minute discussion. So stay tuned for that if you're interested and let's get into this video. When the bike demands the highest degree of symmetry of any sport you'll ever do in your life. And so most of the complexity of fitting a person to a bike is resolving asymmetries, one sided problems, one sided knee pain or foot pain or whatever it is. And so a huge amount of the stuff that we do when we're looking at you off the bike is assessing asymmetries. And we ended up doing a few things and going to suspect, you know, we use this shim underneath your right foot here, which is a leg length compensator. There's two three millimeter shims there. It's basically making your right leg a little bit longer. So it matches your left one because we unfortunately can't make your left leg any shorter as more as much as fun as that would be. And the second thing we did was move your feet a bit further apart to unload your hip impingement a little bit. And the shorter cranks, which we haven't changed today, but I'm nudging you in the direction of trying some 165s because your pelvic posture is very posteriorly rotated on the bike. So you're very much got that C shaped curve to your spine. And if we could anteriorly rotate your pelvis, your head would drop down, your aerodynamic gains would be significant enough that it's worth trying for the few hundred dollars that it costs. And you'll you'll feel I guarantee you just feel better as well. You'll find it hard to quantify, but you'll feel better. Yeah, okay. And so some 165s I think would be a good move for you. And it's only because you've got some pretty decent hip impingement type stuff going on where you've got no available internal rotation of either of your hips because of the orientation of your sockets inside your pelvis. It's a genetic thing. You can't really change it much. Yeah. So the shit. So let's talk, I'm keen to talk about the cranks. Yeah. Because the crank length is quite a if I feel like it's a bit of a one size fits all everyone's 172.5 or 80% the population is. And I don't think that is the case. But before that, the shims, I've never had a shim put in there before and you said something to me that was interesting during the fit that of all the bike fits that you have done over the years, only two people have ever come into the shim. But three quarters of people have a leg length discrepancy and leave with the shim. So what's the explanation behind that? Yeah. So the explanation is that about 75% of the people that came into my clinic to be fitted had already been fitted elsewhere, sometimes multiple times, and they were unhappy with it. So they're seeing me as a third, fourth or fifth opinion. And of all the people that leave my clinic, about three quarters of them leave there with a shim underneath one foot. Now, sometimes it's two millimeters, sometimes it's 20, sometimes it's six, but three quarters of people deal, you know, that they function better with a shim underneath one foot. So of all those thousands of people that have come through my doors, only two have ever come in with a shim underneath one foot, which the conclusion that I eventually came to was that other bike fitters at least in Melbourne don't use leg length shims, which is very bizarre, very strange and a bit depressing, because leg length shims are definitely the best way to account for a leg length difference. Some people advocate staggering the cleat forward, but that comes with other problems where it effectively changes the cleat position of one foot whilst also making the leg effectively longer. It comes with other downsides. Using leg length shims as a way of compensating for structural leg length differences is the best solution that I've ever come across. And I'm happy to change my mind if I ever find a better solution. But yes, as far as I can tell, most bike fitters don't really use shims, at least the people that were coming to see me after being fitted elsewhere. Seeing a shim was rare as hen's teeth. And I think the two guys that brought them in had actually put them there themselves. They weren't put there by the bike fitters. So they figured out themselves through trial and error that they had a leg length difference. So the idea here is that I will no longer be favouring the left-hand side by about 10% in my pedal stroke. Will I become more powerful because of that? It's possible that you'll gain a bit. Yeah, you'll certainly, I find people, the decreased neurological load of compensating, so the fatigue that it induces to create an asymmetrical pedal stroke, once that's taken out of the equation, they tend to find their endurance gets a bit better, even if their outright power output for a 20-minute effort doesn't actually go up a lot. In your case, I reckon you'll pick up a little bit. It might be measurable. You'll certainly feel better and it'll hugely reduce your propensity for developing left-sided knee pains in the future. Yeah, I have had people occasionally pick up big wattages, big like 5-10% gains once we've removed a big asymmetry like a big leg length difference or something from their position. But that's rare. Most of the time, it'll be, the person will feel a lot better. They may not be able to quantify a huge gain. If there's a lot of other things wrong with the position, like the seat is way too high, or the seat's way too far back, or the reach is all wrong, if you change a lot of other things, the gains can be very large if the position was way off where it should have been. Yes. Especially if this or the lack of this was causing you pain, because pain is the biggest detriment to performance you'll ever have, right? As soon as you're in pain or there's an inflammation somewhere, your brain will curtail your energy delivery to your legs so that you can't hurt yourself any further. So you literally become tired when you're sore to slow you down, to protect the joint or whatever it is. So not being in pain tends to be the biggest performance improver. Yeah, okay. Yeah. If your knee's not hurting, you can train harder too. Absolutely. Yeah, you can gain more. And tell me about the crank length, like what's that going to do, and why is everyone supposedly a 172.5? It's one of those things that got ingrained into bike fitting or cycling law, I believe, through repetition. A long time ago, there's a story behind this, I don't know the details, but someone came up with a crank length based upon a mathematical principle and it just kind of stuck and that was it. It was like the ball of foot over pedal spindle idea where you should always have the center of the cleat underneath the ball of your foot exactly. That was just someone said it one day and it kind of made sense and so everyone started doing it and everyone followed the herd and that just became a thing for a long time. Crank length is very much like that. It started out as 172.5 a long time ago for whatever reason and people just stuck with it. In your case, you'll gain from it because of what it will do for your hip impingement. It'll enable you to roll your pelvis forward, your head will go down, the front end will go out and down and your aerodynamic gains will far outweigh any slight power loss if you lose any power. I don't think you'll lose anything. But you said you're learning to lose power at the top and not really like you maybe gained it over a 5, 10, 15, 20 minute effort but maybe the sprint? Yeah, the shorter cranks tend to make you make more of a difference in a positive sense over long efforts because they decrease joint angle speeds and the the length by which your muscle spindles have to change, you know. So they seem to have physiological benefits more over longer efforts in my experience. Short efforts is where it becomes a slight problem. If you've got a big chunky guy who loves low cadence riding and who rides crits and needs to jump on someone's wheel and create an instantaneous burst of torque over a very short effort, you know, three, five seconds, the shorter cranks can cause a problem because you have to sort of wind them up a bit. You don't have as long a lever arm to create instantaneous torque efforts. So that can be a slight downside of going to shorter cranks. So if you're a big chunky, strong guy with a big powerful sprint, you can't maintain good leg speed and you race crits a lot. Well, probably not not going to work out too well for you. But if you're a lean guy who has a big 20 minute power and no sprint, you're not going to lose anything anyway off your sprint because you're never going to be winning a race from a sprint anyway. And so for your physiology, it makes a lot of sense in most of the ways. So it's well worth you trying, rather than just going, I'll just stick with the 172. And if you're going to try, don't go down two and a half mils, go down five or seven and a half mils, go down to 167.5 or 165. You won't perceive almost any change from a 2.5 mil change. You'll start to perceive it at five mils and after seven and a half mils, you'll definitely be able to tell the difference. Yeah, okay.