Each bike manufacturer has their own way of building a bike frame. It may be the carbon layout or it may be how the top tube is designed for aero.
One thing I have learned over the years is that you can’t say you are a 56cm bike frame size, or a medium frame size. There is a large misconception that all mediums are built the same. They will look at you, ask your height, take an inseam measurement and say, ya, you’ll fit a medium, no problem. Next thing you know, you are walking out the door with a spanky new carbon time trial bike or fancy pro racing road bike. However, were you asked what type of rider you are? Or if you have any previous injuries. Or what kind of ride style you like. Maybe you don’t know. However wouldn’t it be nice if you did know before you spent $1000 or $5000?
Fit first is a philosophy I feel very strongly about. With a background deep in biomechanics, I want the athlete to be riding a bike that fits their body, their ride style, their comfort. The only way I feel that is able to be done is on a dynamic fit bike. But be careful. These new and upgraded fit bikes are taking a lot of the art of bike fitting and not taking the riders specifics into consideration. In some of my fit schooling, I’ve seen the new bike fit machines in action, and they will print off a nice sheet that gives you all kinds of bike options. The option list might seem amazing at first, until you read deeper into it. It may show that Brand X in size medium will work however with a 60mm stem, 40mm of spacers and a 17 degree pitch. Not good I say. A medium bike with that short of a stem would ride very squirrelly. Plus the pitch alone will put you right on top of your head tube and make the trail of the bike corner like a Pinto front end on an SUV. Just because a fit unit prints out an option, doesn’t make it right. My next question is, would that person fitting you let you walk out with that bike? I’ve seen it time and time again.
My goal as a fitter using my dynamic fit bike as my main tool of choice, is to find the correct frame size via stack and reach for you, then build the rest of the bike around it to provide the most comfortable and drivable ride you’ve ever have. It will descend well. It will accelerate when you push on the pedals. It will corner like you are on ice skates. Back it up…stack and reach, you say?
Let’s clear up stack and reach quickly. These two crucial measurements are found by measuring from the center of the bottom bracket horizontal over to the perpendicular center of the head tube (reach), and from the top of the top tube vertically down to the intersection of the reach line (stack). Brand X can have a very long and low bike frame stack and reach, Brand Y will have a pretty standard and equal stack and reach (not high or low or aggressive or grand fondo), and Brand Z may be set up for a higher stack to allow for a less aggressive touring/grand fondo position.
Let’s use this medium bike frame from Brand X as an example. This brand offers a great bike, and its geometry, per stack and reach, is fairly aggressive in nature and rides long on the top tube. If I were to suggest this bike to someone, I would want to, as an example, have a 110mm stem with a 6 degree pitch, and 10mm of spacers. This would put the rider as close to the frame as possible and provide a very comfortable ride. But you may say why can’t the person in the last paragraph ride this with that configuration? Well, the rider doesn’t want to ride that aggressively. The rider getting fit does not like an aggressive geometry and may not be of a long torso (compared to leg length). Yet, you will see this rider walking out of a bike shop with a shiny new bike, that if the fit first consideration was taken into account, they would not be purchasing that bike.
When you come in for a refit on your current bike or for a fit on a new bike, I won’t look at you on your current bike. I start with you, the rider. After inquiring on medical history, injuries, current fitness, rider goals, etc. I will get you up on our dynamic fit bike. You are actually fitting yourself, I just get to guide you along. The fit bike allows me to move you while you riding. I can move your saddle up and down and forward and back. I can for the handlebars too. We can swap out seats in the middle of the fit process. We will look at crank arm length. Some video will be taken after we have found our way closer to the ideal position you are dreaming about on a bike. I will capture different positions and work it like an eye doctor. Do you like position A, click the Go To button, and ask if you like position B. You choose. Give me some feedback, good, bad or neutral, and we keep on plugging away until you are in a great ride position of your choice. Don’t worry, I won’t let you end up in a bad position. The coolest feature? If you brought your bike for a refit, or you are upgrading, I can take your current bike fit measurements and put them in the fit unit. Click Go To old bike fit, let you ride it, then click the new fit. In seconds you are moving while riding to feel the dramatic change in position. It’s an opportunity to dial in the fit that is best for you.
Ok, so you are looking for a new bike. The fit unit provides me saddle and handlebar X and Y coordinates - where you want to be in space on a bike. I go to my computer, do some calculations and configure a front end that will ride nicely for you with respect to stem length, pitch and spacer height. From this, I will get stack and reach dimensions. I go to the websites of the bike brand of interest and begin to look at which frame size would work best for you. There are times that there may be a bike you are drooling over, however I am not able to get a front end configuration to work so your ride is ideal. If I can find a front end that will work on the front end, we then begin to spec out your bike to be rider specific (handlebar width, crank arm length, seat post setback, chain ring sizing and cassette ratios).
Getting fit first could be one of the best decisions you make in your bike riding career. It could save you money. It could save you many painful miles. Or it could confirm that you are in an ideal position. Whatever your goals are for your current bike or if you are searching for a new bike, fit first will get you exactly where you should be.