Bike Frame Size Guide

More often than not, selecting and deciding on the correct bike frame size is much more difficult than choosing the kind of bike for yourself, particularly during times like these when online shopping has taken considerable prance.

While you can opt for a mountain, road, or casual bicycle depending on the type of riding you are fond of, when it comes to the size of bicycles, buyers often puzzle themselves if they are not physically present during the shopping.

For you to not get fazed by all the technicalities in choosing the correct bike frame size, we have simplified the points you would need to focus on in this complete guide on bike frame size.

What the Correct Bike Frame Size Should Feel Like

For people who intend to buy the bike through physical inspection, as we suggest you do, it’s analogously easier to determine the correct frame size by seeing how it feels to be on the bike. Simply sitting on the seat post or testing the reach of your feet on the pedals isn’t enough.

Keep the following factors in mind to find yourself the right size:

Standing Over the Crossbar

Notice if you can stand over the top tube or crossbar without struggle or hindrance from the frame. The clearance gap between your legs and the frame should be 2 to 4 inches in case of mountain bikes, and at least 1 to 2 inches for road bikes. This is imperative as it means you could descend from the bike during a stop without hurting your legs.

Reaching the Pedal

Make sure your legs reach the pedals fully. For this, may want to sit on the bike, pedal downwards, upwards and in a full cycle to judge the ease of pedaling. Your feet should not be too stretched or fail to reach the pedal when it’s positioned downwards. A bike frame that is too small would scrunch your calf to the nether thigh causing uneasiness.

Arm Reach to the Handlebar

Your arms may be shorter or longer than your overall height and this is the reason why arm ape index is significant in determining the right bike frame size. When you sit on your bike with the hands gripping the handlebar, your posture must not look funny, to begin with.

More importantly, notice if your back or shoulders and the rest of the upper body hurts after a while. Your bike frame size is disproportionate if there is any discomfort or pain.

Bike Frame Geometry

Understanding the geometry of bike frames could aid you in ascertaining or visualizing the bike frame size, in case you are buying online. The Geometry of the bike frame represents the angles at which the different tubes are arranged and how they slope towards each other. Currently, cycle frames are structured by two types of geometry: Compact and Traditional.

Compact Geometry

The Compact geometry frame incorporates features that are distinct, compared to a contemporary top-tube frame. In a frame with compact angling, there would be 2-3 inches visible clearance of seat-post contrary to the baseline upper tube cycles.

If you are muddling over how to identify the compact geometry frames just look out for the top tube, wheel-base and real triangle. Besides, compact geometry frames consist of a small rear triangle, a short wheel-base, and a sloping top tube. The resultant frame facilitates many stable and responsive rides, thanks to the minimized center of gravity.

Traditional Geometry

The traditional geometry frames are featured by top tubes oriented to the ground. Such geometry bears smaller frames followed by limited spacing, with a mounting over the cycle.

If you would like to compare a traditional geometry frame with a compact geometry frame, a 64-cm traditional frame cycle would be equivalent to a 60-cm compact framed cycle.

Important Measurements Of Bike Frame Size

To determine the correct bike frame size, you’ll have to take 3 measurements of parts of your body. These measurements are especially important if you are planning to order online.

These include your standing height, the distance from your crotch to the top of your feet, and arm length.

Here’s how to determine each:

Inseam Distance

The most vital measurement when it comes to bike frame fitting is the inseam distance or the distance from your crotch to your feet, namely where your pants fall in place at the bottom.

This length will also ensure that the other measurements are correct, thus you may want to take note of the inseam length first. The frame of the crossbar should be at least 2 inches lower than the inseam height so that the rider can stand over the crossbar during brakes.

Standing Height

After determining the inseam height, measure your overall body height correctly. Most of the time, bike size charts are based on either age or height of the buyer.

Besides, the design of the cycle frame should be such that it is proportionate to your height. For more clarity, the ideal top-tube length for a person of (168-175) cm height should be (54-55) cm, thus suggesting a medium-sized cycle.

If your height is about 180 cm, while you choose a small-sized (51-53) cm top tube, your legs would not even reach the pedals properly.

Arm Length

This is fairly easy to determine using the ape index, which is the ratio of your stretched arm span to your overall height.

Measure your arm span from one end to another and compare it with your height. If your widespan is shorter than your height or if it is less than one, your reach is short. For more than 1 ape index your arms reach is longer.

People with longer reach should opt for larger sized bikes, while people with shorter reach should consider buying smaller sized bikes. Those of you who have a proportionate wingspan to height ratio and an ape index of 1, would be most suited to a medium sized bike.

Bike Frame Sizes for Women

Due to different anatomy, a woman and a man of the same height would need bike frames that are significantly varying in size. This is because women generally have tiny torsos but a longer stand over height. Generally, women are most comfortable with smaller frames and shorter top tubes on the frames. This enables women to bring the handlebars in proximity to the saddle while also expanding their legs fully.

Women-specific bikes and frame sizes are not limited to use by women only. Men or larger children who are shorter than 165 cm, or have a lower arm index may want to consider smaller bike frames and narrow handlebars.

Bike Frame Size Chart for Mountain Bikes

Body Height Inseam Height Bike Frame Size
4-10’’ to 5-2’’ 25’’ to 27’’ XX Small
5-2’’ to 5-4’’ 28’’ to 29’’ X Small
5-4’’ to 5-6 β€˜β€™ 30 to 31’’ Small
5-7’’ to 5-9’’ 32 to 33’’ Medium
6-0’’ to 6-4’’ 34’’ to 35’’ X Large
6-3’’ to 6-6’’ 35’’ or more XX Extra Large


Bike Frame Size Chart for Road Bikes

Body Height Inseam Height Bike Frame Size
4-10’’ to 5-2’’ 46-48 cm XX Small
5-2’’ to 5-4’’ 48-50 cm X Small
5-4’’ to 5-6 β€˜β€™ 51-53 cm Small
5-7’’ to 5-9’’ 54-56 cm Medium
6-0’’ to 6-4’’ 56-60 cm X Large
6-3’’ to 6-6’’ 60- 64 cm XX Extra Large


Bike Frame Size Fitting

Once you have figured the correct bike frame size, you may want to configure the fitness of the remaining parts of the cycle frame. Firstly, you would need to determine if the stem upon which the saddle is placed is proportional to your body. If not, modify it accordingly, as you might fail to reach the pedals otherwise.

Furthermore, you may have to adjust the positioning of your saddle itself. Vary the fore and aft position, along with your saddle tilt angles. Last but not the least, the separation between brake levers and the angle between the handlebars will ensure your comfortable fit to the cycle frame. We suggest you take the position of choice while seated on the saddle as you adjust each fitting.

Final Thoughts

The right bike frame size will ensure your bike rides are a more satisfying experience. Choosing the correct bike frame size may become a hurdle if you know what constituents to consider and which measurements to focus on.

Even if you have the measurements in place and our bike frame size guide to help, it is best to arrange a test ride before picking out just a pretty bike.

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