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The Bike Fit with Todd - Part One

The Bike Fit, Part One; Understanding bike fit.

In this two part article Todd Jones will discuss bike fit. We will touch on overarching philosophies behind the bike fit to provide our reader a basic understanding of what a bike fit is and some common considerations when looking at having a correctly fitting bike. Such as which Type of Bike Fit; Bike Fit Bandwidth; Pain Vs Performance; along with Aerodynamics, Comfort and Power.

Bike fitting is process of adjusting a bike for a cyclist to optimise their comfort, performance and efficiency. A Bike fit aims to prevent injuries, increase efficiency, comfort and improve performance for all cyclists.

You have finally brought yourself that dream sled via Bike Chaser, it’s the right colour, it just looks fast and brings a massive smile to your heart but now for the all-important part, ensuring your machine is set up just for you. Let’s consider your new bike (or even your loyal current steel steed for that matter) to be an extension of you and you are an extension of it.

You are one with this weapon and it’s imperative we properly connect human and machine. 

All too often we come in contact with folks who are just beginning their journey into all that is great about riding only to hear that their experiences are plagued with sore lower backs, aches in the neck and shoulders, foot numbness or the dreaded knee pain. Whilst there will always be an adjustment period to a new activity or position, sustained discomfort should never be present.

So in this two-part piece, we are going to discuss bike fit. In the first part, we will touch on overarching philosophies behind the fit before discussing some of the basics of a bike fit in part two. 

Which Type of Bike Fit

Just like there are trade-offs when choosing a bike between comfort, performance, and weight, when we are choosing which bike fit, we face a similar trade-off in that between a traditional cost-effective solution or a professional dynamic video analysis based fit.

Consider the bike fit process to be similar to that of maintaining a formula one car compared to a typical service for your daily drive. We wouldn’t exactly take an F1 car to our local KMART Tyre and Auto Service, whereas it might be overkill to take our daily driver to the Scuderia Ferrari Racing headquarters in Maranello, Italy. Depending on how hard you broke open the piggy bank for your new two-wheeled sled will determine what is practical in regards to selecting an appropriate bike fit.

I will always recommend a professional dynamic bike fit which will begin with a physical assessment, identifying mobility constraints and any side to side differences of the rider before utilizing video analysis to adjust the bike to the rider. The advantage of this form of assessment is it takes into account the dynamic nature of the rider and offers a true picture of what is going on, but this can be quite expensive and impractical for many. 

The Bike Fit with Todd - Part One Flowchart The Bike Fit with Todd - Part One Flowchart

Bike Fit Bandwidth

Bike Fit Bandwidth or “Window” as it is also known, is addressing a key concept in fitting a rider to a bike, that there is no single best bike fit for any rider, let alone a group of riders. If you take home one concept from this article, let it be this one, so we will say it again for those in the back to hear, there is no single best bike fit. Rather, there is a bandwidth in which a rider will fall into with some room to breathe within that “window”.

For example, we can fit a rider to a bike on a Friday afternoon, they have been driving to and from work all week, stuck at the desk or digging trenches, been waking up to an alarm and potentially severely lacking in mobility. We then fit that rider on a Sunday night after a relaxing weekend, maybe they have fit in some physical activity so they are moving a lot better, haven’t been chained to a computer screen. These two fits are going to be quite different yet we are dealing with the exact same rider. 

When it comes to fitting folks to bikes, there is often a belief we need to place riders within certain angles and distances on the bike.

There is formulae such as halving the age of a honey badger, dividing it by the length of your downtube, rubbing that number in the sweat of a Columbian climber before multiplying it by the number of sunflowers you see on stage eight of the Tour De France coverage.

But it’s imperative to understand when we try and fit riders to a group of averages or a set system, they usually fit no one. 

In the 1940s, the US Air Force was having serious issues with their pilots controlling their machinery. By the 1950s, a task force was set up to address the dimensions of the cockpits. Over 4000 fighter pilots were measured across 140 different dimensions, the belief was they could collect the data and develop a clear indication of the average pilot and thus create a suitable cockpit.

At the time, there was a young scientist observing this task force who asked the question “how many of these pilots really were average”. The young chap grabbed what he believed were the 10 most relevant dimensions and set off figuring out how many of the 4000 plus pilots were within the average range across dimensions. The answer, ZERO.

Even when he took what he then believed to be the three most critical dimensions, once again, out of the 4000 pilots, less than 3.5% of pilots fell within the average range across all critical three.

When you try and fit people to an average you will end up fitting nobody.

One look at a professional peleton or watch along with any world cup mountain bike race and you will see a plethora of riding positions within a vast array of riding situations. So the idea that there is one magic bike fit is wishful thinking. 

There will also be outliers, some will look to the likes of the all-dominating three-time EWS series champion Sam Hill and his bike fit, simply measuring the distance between the pedals and the grips before he licks the stamp and sends it downhill. But Sam Hill is Sam Hill, one must earn the right to be as laid back as Sam.

Pain Vs Performance

When considering a bike fit, there are also many layers of variables to consider, the first and what I would argue the most important is our compromise between reducing pain and enhancing performance. It would be fantastic if these two were mutually exclusive but they aren’t, when we increase one, we usually decrease the other.

A fit which is at the comfortable end of the scale will more often than not have the rider in a more upright position, is this fantastic for aerodynamics? Not particularly, but if a rider cannot ride at all, well then that is worse than a rider decreasing their aerodynamic potential.

The phrase “Primum non nocere” is appropriate here, “first, do no harm”.

There will be a time and place to chase those aero gains and ensure the engine room can create the maximal amount of power to turn those cranks over, but to begin with, we first must do no harm and ensure the rider is in a comfortable and sustainable position.

Aerodynamics, Comfort or Power

"The hunter who chases two rabbits, catches neither one". Well in this case, if we chase three rabbits ~ Aerodynamics, Comfort and Power, we end up catching neither.

It’s important when we are first beginning our bike fit journey that we identify a clear target (for most it will be either comfort or power, aerodynamics can be tough for those lacking sufficient mobility).

When we clearly identify our aims, it will ever so slightly narrow the fit bandwidth. For example, when chasing a comfort-based fit, we won’t go to the extremes in regards to seat height or walk a fine line with ‘knee of spindle’ angle, simply because as we start to explore the corners of our range to enhance power, the risk of discomfort and injury rises also.

Wants Vs Capabilities

Finally, we reach a trade-off in regards to what the rider wants versus what the rider is physically capable of.

As with all of our compromises, they will change over time and develop as a rider develops more mobility, becomes comfortable in a position and capable of making further micro-adjustments in the hunt for extra wattage. But very few of us will be able to immediately hold the aggressive positions we see in the professional peloton or that of the Nino Schurter’s and Jolanda Neff’s of the world (no matter how badly we want to look like them).

As you can see, there is a lot that goes into the bike fit and all too often bike stores offer complementary fits with any new purchase. Take advantage of these if you are at all unsure about your fit because their aim is your aim, to enjoy your riding.

In part two, we will look at what exactly goes into a bike fit, discussing each position of note and what they mean for the rider.

 

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