How to custom fit your bike

Riding a bike that actually fits will go most of the way towards having a bike that rides well.  The more you ride, the more you will notice people perched atop shockingly fitting bikes.  If you aren’t keen on paying hundreds of dollars to get a professional bike fit, with a few simple steps your bike can fit you as well as your lycra.

Get the right frame size 

If you don’t have the right size frame, you’re just shifting deck chairs on the Titanic.  Start out with the right frame size and fit the bike from there.  Here’s a rough conversion of your height to frame size.

bike_size_guide_mens_semi_compact

The most important measurement concerning frame size is your top tube length, which is the distance between the end of the handlebars and your seat post.  There isn’t a definite calculation for this measurement due to the huge amount of anatomical variation between riders, so the best way to get this measurement right is to sit on the bike.  The default position on a bike is with your hands on the hoods, so you should be able to reach this position comfortably, with a slight bend in your elbows and your back at an angle of approximately 45 degrees.

Saddle height

IMG_1366.JPG

Your saddle height has to be relative to your frame.  If your bike is starting to look like this, it’s time to up your frame size.

If your top tube length is set correctly, the next thing to consider is your saddle height.  Your saddle needs to be positioned correctly to obtain maximum efficiency, otherwise you start to use muscles that really aren’t great for pedalling.  To determine the optimal saddle height, clip into your pedals and put them in the 6 o’clock/12 o’clock position.  The extended leg should be almost straight, with a slight bend in the knee.  For those looking for a more exact measure, you can try the 109% method.  No surprises here, according to this method, your saddle should be set at 109% of your inseam measurement, the distance between your crotch and the floor.  To calculate this one, stand facing a wall, hold a thick book between your legs in the same position a saddle would sit, and mark the height of the top edge.  Multiply this number by 1.09 and there you go, the perfect saddle height, measured from the floor to the top of your saddle.

Saddle, stack and stem

Since you have to balance having the right saddle height with the correct reach, you’ll need to make micro adjustments to fit your bike perfectly, and these are done by either changing your stem length, your saddle position, or rearranging your spacers on the headset.  If you find you’re leaning over too much, raise the height of your stem by putting more spacers underneath.  If your arms are too straight, try a shorter stem, or slide your saddle forward a few centimeters.  This final stage of bike fitting is the most laborious, and may require a bit of trial and error.  A standard road bike stem is 11cm, and if you’re finding that your reach isn’t quite right, you can swap the stem out for a longer/shorter one.  Beware, you can only move two centimeters either way before you start throwing your steering out of wack, so while you might see the pros on their 155 millimeter stems, but leave that for the pros – keep it between 9 and 13 centimeters.

The problem with fitting a bike is that it’s so subjective.  What you want out of your bike will drastically change how it should fit.  If you’re looking to destroy every Strava segment you can find, you’re going to want to raise your saddle, slam your stem and increase your reach.  This will get you down into an aerodynamic position, but can also give you back problems if you ride like this frequently.  If you’re solely looking to cruise around in comfort, drop the saddle a bit and shorten your stem.  This puts you in a more upright position, perfect for climbing, or for those with back problems that prevent them from leaning forwards in a more aggressive riding position.

Apply these simple tips to your bike to get your bike better fitted, but of course, the best way to get a perfect fit is to organise a bike fit at your local bike shop.

About Tim_Davis@Pushys

I'm a Science Graduate and Medical student at the University of Queensland, specialising in anatomy and physiology. More importantly, I'm all for any type of riding; road, mountain, dirt jumping, I love it all! Let me know if there is anything you want to know about nutrition and health, and I'll do my best to help you out!

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