Bike fitting - finding the perfect size

April 5th 2020
Selecting the right sizing for your frame and components can be intimidating. However, finding the right bike for you does not need to be as complicated as some might have you believe.

When starting from scratch, the ideal way to find you correct size and positioning is through a qualified bike-fitter. Bike-Fiting today has become more of a science than the "Black Art" it once was. Most cycling communities today have access to a competent bike-fitting studio.

As a web based company, we do not offer these services. There are so many personal variables and preferences to be taken into account when determining your most efficient position that we felt an online "Bike Fit Bot" would give our customers a false sense of certainty.

If you have a previous bike that you are satisfied with your positioning on, however, emulating that position onto a new bike is actually quite simple. 

We believe Stack and Reach are the only true references required to base your bike sizing on. These two values determine the position of the three contact points between your body and your bike (Crank position relative to handlebar as well as saddle position). Get your Stack and Reach right and you can easily match the fit of your old bike. 

You should be able to find these numbers using a google search, websites like geometrygeeks.bike offer free access to a database of most of the common bike brand's geometry tables available online.

Saddle height and set-back can be adjusted after you recevie your bike. Except in the most extreme cases this is not a critical factor when selecting your frame size. For a great starting point for your saddle height, one of the most accurate and simplest methods was developed by Tour de France winner Greg Lemond in the 1980's; taking your leg inseam and multiplying it by 0.88 (ie 79cm inseam x 0.88 = 69.5cm seat height). From this starting point you can adjust a few millimeters up or down based on saddle, pedal type, shoe sole thickness and feeling, but its a real good start.

Proper "set-back" should position the tip of your saddle approximately 5-10% of your saddle height behind the vertical line drawn through the crank axle. You can measure this by dropping a plumb line off the tip of your saddle.

The 0.88 and 10% rules are good starting points and will put you close to a really good fit. You should be able to acheive this position on nearly any frame size, due to the large range of seat post extension possible.

Bar/Stem height is more limited by frame size and it is thererfor critical that you choose the correct frame. We recomend never using more than 20mm of spacers between the top cap of the headset and your stem, meaning you have only 20mm of adjustable height. Stem length is obviously more flexible as stem lenths range from 80 to 130mm.

We suggest you compare the Stack and Reach numbers for your current frame to the geometry of our frames. For exampe, if your current frame has a Stack of 550mm and you currently have 10mm of spacers under your stem, then by choosing a frame with 540mm of Stack and and using 20mm of spacers you would end up with exactly the same bar height. Likewise, if your current frame has 390mm of Reach and you use a 100mm stem then by using a 110mm stem on a frame with 380mm of Reach you would be within millimeters of your current position. 

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Stem Length

The length of your stem is a critical determining factor in bike fit. A short stem will result in a shorter reach overal from saddle to handlebar. When the stem is too short you will sit with a large curvature in the spine, resulting in dis-comfort and in the worst case restricted breathing. A stem that is too long will result in the rider over-reaching, adding extra strain on the lower back and core muscles and possible lower back pains.

Most riders have an opinion already about what works for them. We recommend 100mm stems on smaller frames and 110mm on M-L sizes as starting points. The great part of buying a bike from us is that you are free to choose whichever size you prefer and we'll even offer to switch the stem out after you've made your purchase if needed. 

Gear Ratios

On each of our F|AR and F|DISC builds we offer you several choices of gear ratios which will help you choose the bike which is perfect for your needs. This feature is unique to FARA Cycling.

Regular: Usually a 52x36 front chainring and an 11-28 rear cassette. This set-up is the industry norm and perfect for capable riders living in areas without extended or very steep climbs.

Compact: Usually a 50x34 front chainring combined with an 11-30 cassette. This is a great set-up for riders who live in hilly terrain or just want a little extra gearing to get up the steepest parts of the climbs.

Super-Compact: Using a 50x34 front chainring combined with an 11-34 rear cassette offers a 1-1 gear ratio at the top of the range. This is a massively easy gear that should get any cyclist up pretty much any climb. Choose the Super-Compact option if you live in or travel to areas with long, steep climbs and feel you could use a little assistance through easier gearing.

Handlebar Width

Handlebar size is generally related to your shoulder width but recently a few other factors have come into play.

The normal options vary between 40cm to 44cm with 42cm being the absolute most popular size. Smaller riders and women may also look into an even smaller 38cm size.

To measure the proper width with regards to your own body, follow these steps:

1. Have someone find the bony protrusions on the front of your shoulders and measure the distance between each shoulder.

2. Add 2cm for your ideal handlebar width.

There is a trend in the pro-peloton towards narrower bars. the reasoning behind this is better aerodynamics and also being able to squeeze through gaps between riders when fighting for position in their aggressive packs.

Another trend surfacing with the emergence of gravel riding is wider bars, offering more varied hand positions for longer rides, more space for handlbar-loaded luggage and more control on technical descents.

For the rest of us, these issues should be secondary to comfort as well as an open chest for better breathing. If in doubt, just take 42cm :-P

Crank Length

Scientifically determining correct crank length is a complicated subject with several valid theories abound. In lieu of a professional bike fit, we as an online direct brand have determined default crank lengths that we build all of our bikes with:

All bike sizes under 53cm will be built with a 170mm crank.

All bike sizes 53cm and over will be built with a 172.5mm crank.

All F|GRAVEL and 1x builds will be built with a 172.5mm crank.

If you should prefer another alternative, please mention it in the comments field when checking out and we will be happy to accomodate you.