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Bike Fits Explained: Everything to Know

August 01, 2019
Bike Fits Explained: Everything to Know

Arguably one of the most important factors to a rider's performance, enjoyment and comfort on the bike lays in how the bike fits a rider. Regardless of what riding discipline you do or are thinking of doing, an improperly fitted bike can have a dramatic impact on your ride, and can even result in an injury.

So with the help of Lucas Owen at the Cycling Physiotherapy Centre, in this guide, we'll walk you through all you need to know about getting a bike fit, including some simple tips and tricks you can use at home.

What is a Bike Fit?


Similar to a runner being fitted up for a pair of shoes, being correctly fitted to your bike has a significant effect on your comfort, injury prevention and performance on the bike.

A bike fit is comprised of several factors and can be of benefit to riders of any ability. Such a thing is typically based around optimising the contact points (handlebars, pedals, saddle) on the bike based on your biomechanics (how your legs and arms move on the bike). In addition to increased efficiency, a bike fit typically provides injury prevention, meaning no more niggling aches and pains after those long days in the saddle.

It's important to note that not all bike fits are the same. There's a big difference between a quick fit to set your saddle height and cleats, and a three-hour session that includes a full biomechanical assessment, component swapping and a follow-up appointment. In this article, we'll be focussing on the process for road bikes and mountain bikes, the adjustments a fitter is likely to make, and some you can check at home.

The Bike Fit Process


Ultimately, the purpose of a bike fit is to improve a rider's efficiency on the bike by making a series of adjustments to the components fitted. So regardless of the level of bike fit a rider undertakes, there are many fundamental similarities between them. These include adjustments to cleat position, saddle fore and aft, and saddle height.

Cleat Position


Cycling cleats are mounted to your riding shoe and are what "lock you in" to the pedal. This 'clipless' setup allows the most efficient transfer of power through your bike. Road shoe cleats typically have a three-bolt system with a larger surface area, so this transfer isn't compromised in any way, while your standard mountain bike cleat is a two-bolt system designed to consider walking and debris clearing.

Apart from different system compatibility, the main difference in cleat selection is that of' float'. Float is measured in degrees and is the range your feet are allowed to move freely without restriction on the pedal surface. Generally, the less flexibility and experience you have, or the more at risk you are for knee or leg injury, then the more float you should adopt.

Cycling shoes feature room for both fore and aft cleat adjustment, all of which have an impact on how you progress through a pedal stroke, and the muscles activated.

Ideally, cleats are to be positioned in such a way that the ball of the foot is in-line with the pedal axle. Positioning the cleat too far forward results in a toe down position, requiring more calf muscle activation, while conversely, positioning the cleats too far rearward can result in the leg "locking out" placing more strain on the quadriceps, and the back of the knee.

One trick Lucas uses is to mark the joint position of your first and fifth toe on each foot with a small sticker or similar. Using the middle of the pedal as a guide, the line between these two joints gives you a ballpark for your ideal neutral cleat position.

Saddle Height


Following cleat positioning, saddle height will typically be the next contact point to be adjusted. The main culprit of an incorrect saddle height is knee pain. Too high and riders are likely to experience pain in the back and/or inside of the knee. Conversely, too low, and pain is likely to be found at the front and/or outside of the knee.

Finding the correct saddle height can have a significant impact on your comfort on the bike, significantly reducing the strain on your joints and making your leg muscles perform at their efficient best. The saddle height measurement is taken from the centre of the bottom bracket, up to the seat tube, to the middle of the saddle, where your sit bones are likely to rest.

There are several different methods that bike fitters undertake to find the correct saddle height; some, like Lucas, make use of software and mapping to track hip and knee angles, while others use a more fundamental approach. In a pinch, one method that is tried and true and used by a wide range of fitters doesn't require any software at all and is quickly undertaken at home.

The process involves you sitting on the bike, unclipping, and place your heel in the middle of the pedal axle with it at the furthest point so that the crank is in line with the seat tube. Your hips should not have to rock to reach the pedal, but your leg should be completely straight so that when you clip in, there is a slight bend. This method is proven to be effective in ballparking your ideal saddle height. However, it's essential to pay attention to the saddle fore and aft too, more on that below.

A note on saddle choice; Saddle selection is as personal as music taste, what feels right for one rider can be hell for another. Most bike shops offer a saddle selection service whereby potential buyers can measure up their sit bones, and find a saddle that suits their needs and budget. Some store may go as far as providing test saddles for riders to put the new component through its paces before making a purchase. Check with your local store for more information.

Saddle Fore and Aft


Once the saddle height is dialled in and feeling natural, the next step is to adjust the tilt, fore and aft positioning of the saddle. Most saddles and saddle clamps present a range of adjustment capabilities to riders and professionals wanting to fine-tune rider comfort.

Saddle tilt refers to how "level" a saddle is in relation to the ground. Lucas says that for road riding, most professionals err on the side of neutral here, positioning the saddle to it supports the rider, allowing them to comfortable ride "hands-free" without feeling like they're sliding off the saddle.

Saddle fore and aft positions refer to where the saddle rails clamp atop the seat post. It's this measurement that has the most impact on how much weight a rider places through their hands, as well as the angle and position of the knee in relation to the foot. It's worth noting that many different biomechanical factors can impact this, including rider flexibility, core strength, and so on.

While professionals are more likely to rely on precise knee angles, software and rider tracking, the most common method used by bike shops and DIY bike fitters is the tried and true "Knee Over Spindle" method. This method involves a rider sitting on the bike with the pedals aligned parallel to the ground; then a plumb bob is dropped straight down from the top of the knee cap down to the ground. Ideally, the line should intersect the pedal axle. If the line falls in front of, or behind this line, this would indicate a saddle adjustment fore or aft is required.

It's worth noting that this is a crude test and won't be 100% accurate in all cases as it won't take into account your body type, injury history or pedalling style. If you're still having discomfort, check in with a professional bike fitter for a more in-depth assessment.

Handlebar Reach and Stack


Once the cleats and saddle position is dialled, the majority of the fitting process is more or less taken care of, as these have the most significant impact on overall comfort on the bike. The final piece of the puzzle comes at the front end of the bike, in the form of the handlebar reach and stack.

The reach refers to the distance from the tip of the saddle to the base of the hoods/centre of the grips. The aim here is to ensure that riders have a relaxed elbow position, if you're reaching too far, locking the elbows when you ride, this is an indication that your cockpit is positioned too far forward requiring either a saddle fore/aft adjustment or a change in stem length. Conversely, if a rider finds themselves couped up, with an extreme angle at the elbow, or the knee is striking the bars when riding out of the saddle, this is an indication that a more extended setup is required.

The tilt of the handlebar is also looked at here, with Lucas again stating that professionals typically err on the conservative side. For road bikes, Lucas recommends a setup where the hoods sit both parallel to the ground both horizontally and laterally. This places the hands and wrists in a relaxed and robust position, minimalising the risk of fatigue, numbness and discomfort.

Other Considerations


While the adjustments above are critical to a rider's position on the bike, they do not take into account other considerations such as flexibility, joint mobility and other physiological attributes different riders are likely to have. It's for this reason we highly recommend seeking out a professional if you have a history of injury, any niggling aches or pains, or are interested in extracting the most performance out of your position on the bike.

Additionally, any tips or advice given in this article is general in nature, does not take into account your biomechanical and physiological information, and is to be undertaken upon at your own risk.

Thanks to Lucas Owen at The Cycling Physiotherapy Centre for providing his knowledge and insights for this article

Looking to find your fit? Browse the range of bike services on offer from leading industry professionals right here, at BikeExchange

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