A Junior’s Guide to Road Bicycle Sizing/Fit

The purpose of this guide is to provide information and resources to

parents of junior cyclists. This guide focuses on the process of

finding junior road bicycles and properly fitting your junior

cyclist(s) to their machine. This guide will also provide an

explanation sizing and adjustments to maximize your junior cyclist’s

safety, comfort, and power output. Optimal angles for your cyclist’s

joints whilst on the bike will also be discussed. Links and resources

to frames/parts will be provided.

By: Aidan Pounder

Table of Contents

Introduction ……………………………………………………………………………………………………………………………………………… 1

Bike Frames ………………………………………………………………………………………………………………………………………………… 2

Wheels ……………………………………………………………………………………………………………………………………………………………… 3

Crankarms ……………………………………………………………………………………………………………………………………………………… 5

Handlebars …………………………………………………………………………………………………………………………………………………… 6

Shifters/Levers ……………………………………………………………………………………………………………………………………… 7

Gearing …………………………………………………………………………………………………………………………………………………………… 8

Pedals ……………………………………………………………………………………………………………………………………………………………… 9

Other Parts ………………………………………………………………………………………………………………………………………………… 10

Bike Fit ………………………………………………………………………………………………………………………………………………………… 11

Website Links …………………………………………………………………………………………………………………………………………… 12

References …………………………………………………………………………………………………………………………………………………… 13

1

Introduction

This guide serves to provide information and resources to find

properly fitting road cycling frames, wheels, crankarms, and various

other cycling parts for junior cyclists. Besides discussing cycling

parts, this guide shall cover the proper fitting of your junior

cyclist on their road bike and the optimal angles of his/her joints on

their machine. The purpose of covering a junior cyclist’s “bike fit”

is to increase the cyclist’s control, safety, comfort, and power

output on the bike. A proper “bike fit” will also nearly eliminate the

possibility of your junior cyclist damaging their muscles or joints

while pedaling their road bicycle.

This guide will comprehensively cover junior road cycling bikes and

equipment in an unbiased manner without promotion of specific products

or brands and will only highlight brands based on their suitability

and attention to junior riders in their manufacturing. This guide will

also provide links to websites that have junior bicycle frames and

various road bicycle parts to help you along your journey in getting

your junior cyclist on the road!

The figure below may serve as a reference point if the reader is

unfamiliar with bicycle parts referred to throughout this report.

Figure I

Bicycle Parts

2

Bike Frames

BEWARE, many bicycle distributors will attempt

to sell you a bike frame based on your junior

cyclist’s age. Age IS NOT an accurate

determinant in properly fitting a bike frame

to your junior cyclist.

The best way to find a suitably fitting road

bike for your junior cyclist is to base your

purchase off your child’s height and inseam.

Grab a tape measure and measure your junior

cyclist’s height and inseam as accurately as

possible.

Note, your junior cyclist does not necessarily

need a “road bike frame”, as cyclocross bikes

and even BMX bikes can be converted.

The best way to find a well-fitting bike frame

for your junior cyclist is to have him/her to

physically sit on the bicycle.

Using bike fitting methods while watching your

junior cyclist sitting/riding on a bike and

making an educated decision is the best way to

determine frame sizing.

Figure II

Graphic Bike Chart

3

Wheels

The best way to find suitably fitting wheels for your junior cyclist,

is to follow the same method as listed above for bike frame sizing.

Choosing a bike size based on frames or wheels, will most of the time

point you in the same direction.

Accurately measuring your junior cyclist’s inseam is very important for

this stage of building your bike.

Wheel size is one of the most confusing aspects of cycling parts, as the

same sized wheels can be referred to in a multitude of different ways

across the different disciplines of cycling.

First and foremost, 24”, 650C, and 700C wheels will be the wheels you

will most likely come across in the world of road cycling.

Figure III

Kids Bike Sizes Chart

4

Figure IV above, details the different ways the same sized wheels can

be described.

Wheels typically are described by the wheels’ diameter in inches up until

the 24-inch size. A 26-inch wheel doesn’t exist in cycling, as that sized

wheel is referred to as a 650a/b/c.

The a/b/c refers to the width of the tire that fits around the rim of

the wheel. You will only need to be concerned with “c” wheels in road

cycling.

A 28-inch wheel is referred to as a 700c wheel, the industry’s standard

size.

Figure IV

Bike Wheel Conversions

5

Crankarms

As a rule of thumb, crank arm length should be determined by your junior

cyclist’s height. The crank arm length should be 10% of the rider’s

height plus 5mm.

Crank arm length in millimeters = (cyclist’s height • 0.10) + 5mm

Crankarms are difficult to find in small enough sizes for junior

cyclists, and the answer can sometimes be found in the BMX world.

It is important to note, that the BCD layout should also be considered

when purchasing cranks.

The BCD layout is the chainring bolts layout, or more simply put, how

many bolts are needed to attach the crank arm to the bike.

As an industry standard, road bicycles are fitted with 5 bolt cranks.

Smaller crank arms are more typical in the off-road disciplines of

cycling.

Figure V

Crankarm Length

6

Handlebars

Fitting your junior cyclist with the proper handlebar width will not

only reduce their aerodynamic drag on their road bike, but more

importantly improve comfort and control over the bike.

The benefit of properly fitting handlebars also includes reducing

shoulder tension, neck pain, jaw pain, or even hand fatigue while

riding.

The most common advice you will likely receive involving handlebar

width, will be to match the rider’s shoulder width to the handlebar

width. Though this a good starting point, ultimately whatever width

feels best to your rider, whether slightly narrower or wider than

their shoulder width, is the best route to take.

Figure VI

Handlebar Width

7

Shifters/Levers

The main concern when discussing shifters and brake levers for junior

road cyclists is their ability to use components effectively.

Braking is a necessity, and these bike components need to be operated

by smaller hands with weaker grip strength.

Kids and junior bikes tend to come with older and heavier equipment,

so keep that in mind. Shifting and braking levers are usually quite

stiff and require larger hands with greater grip-strength.

The best solution to this problem is short-reach shifters with double-

tap shifting.

Some of the best short-reach shifter options for junior road cyclists

include: MicroShift R9 Dual Control levers, Sram Red ETap shifters,

and Sram Apex DoubleTap shifters.

Figure VII

Sram Apex

Figure VIII

Sram Apex

Figure IX

Sram Apex

8

Gearing

BEWARE, if your child wants to race on the road – no bicycle you

purchase will come with junior gearing.

Junior gearing is implemented to encourage good pedal cadence and

reduce chance of injury.

Junior gearing is tested at all junior road cycling events, whether

road race or criterium.

The “rollout method” or “junior rollout” is a test in which the bike

must be rolled backwards 26 feet in a straight line in the bike’s

smallest cog (or hardest gear to pedal). The crank must be at a 90-

degree angle to the ground and must complete a full pedal revolution

within the 26 ft boundary.

A 52x14 (52 tooth chainring and 14 tooth smallest cog) is the most

common gearing used to pass junior rollout.

Other gearing combinations for junior cyclists include 44x34, 52x36,

and 41x33.

Figure X

Junior Rollout

9

Pedals

There is an abundance of different types of pedals: standard pedals,

toe clip or toe cage pedals, power grip pedals, and clipless pedals.

Any bicycle bought from a bike store or manufacturer will come with

standard pedals.

Toe clip/Toe cage and power grip pedals offer an intermediate step

between standard pedals and clipless pedals.

If your junior cyclist is at the point where they are ready to make

the next step to clipless pedals, then be careful which cleats/pedals

to use.

The biggest concern with clipless pedals and junior riders is their

ability to unclip from the pedals when coming to a stop.

The best type of clipless pedals for junior road cyclists are

Speedplay Ultra Light Action pedals, Look Keo 2 Max pedals, and Time

XPro 10 pedals.

Figure XI

Standard Pedals

Figure XII

Toe Cage Pedals

Figure XIII

Speedplay Pedals

10

Other Parts

• Side Winder bottle cage, as it needs to be as easy as possible

for your junior cyclist to grab and put back their water bottle

• Think about looking at shorter stems for your junior cyclist, as

their elbows should not be locked and fully outstretched. Your

cyclist’s arms should be slightly bent to improve control over

the bike and limit impact on the cyclist’s joints

• Adjustable saddles are something worth looking into, as they can

improve fit and comfort for the rider

Figure XIV

Adjustable Saddle

11

Bike Fit

Bike fits are the process of fitting your cyclist to their bike,

so he/she is as comfortable as possible, fully in control of the

bike, and most importantly not damaging their tendons or muscles

while pedaling.

The first, and simplest step to your junior cyclist’s bike fit, is

their saddle height. Ideally, when your junior cyclist is sat on

the saddle, their toes should be touching the ground and the cyclist

should not be flat footed.

With all steps of bike fitting, the best way to go about this

process is by use of a stationary trainer. Saddle height is best

determined by pedaling rather than the toe method discussed above.

Your junior cyclist’s knee center should be directly above the

center of the pedal when the crankarm is parallel to the ground.

Your junior cyclist’s knee needs to be bent between a 27- and 37-

degree angle when extended at the bottom of his/her pedal stroke

to prevent damage and injury to muscles/tendons while pedaling.

The optimum angle for your junior cyclist’s shoulders is as close

to an exact 90-degree angle as possible between the rider’s torso

and upper arms.

Figure XV

Saddle Height

12

As shown above in Figure XVIII, the optimum angle for your junior

cyclist’s elbow should be approximately 15-degrees.

If you follow the advice provided above and reference the figures

provided, then your junior cyclist should be comfortable and in

control of their machine!

The information provided create the steps for a basic bike fit, but

discomfort on the bicycle may persist. This oftentimes can be solved

by adjusting the cleat position on the base of the cycling shoes (if

your junior cyclist is using clip-less pedals)

BEWARE, adjusting cleat position can seriously affect the rider’s

pedal stroke and should be done under the presence of a professional

bike fitter

Figure XVI

Knee Over Pedal

Figure XVII

Knee Angle

Figure XVIII

Shoulder Angle

13

Website Links

• Road Bicycles Designed for Junior Cyclists

➢ Isla Bikes

➢ Frog Bikes

➢ Specialized Bikes

• Clipless Pedals for Junior Cyclists

➢ Speedplay Ultra Light Action

➢ Look Keo 2 Max

➢ Time XPro 10

• Other Parts for Junior Cyclists

➢ Side Winder

➢ Croder Cycling Cranks

➢ Sram Apex DoubleTap

14

References

BikeRadar. (2020, December 18). Speedplay light action Chromoly Pedals review. Retrieved

April 08, 2021, from https://www.bikeradar.com/reviews/components/pedals/speedplay-

light-action-chromoly-pedals-review/

KidsRacing.CO.UK. (n.d.). Our guide to Kids BikeFit for YOUTH/JUNIOR CYCLISTS.

Retrieved April 08, 2021, from https://kidsracing.co.uk/blogs/bikes/guide-kids-bikefit-

youth-junior-cyclists

Martins, N. (2021, February 16). Kids bike SIZES guide and Chart: Don't buy the wrong Size

Bike! Retrieved April 08, 2021, from https://www.twowheelingtots.com/kids-bike-sizes-

guide-a-new-trick-to-finding-the-best-fit/

McKenzie, E. (2021, March 04). Kids bike size chart: The definitive guide to kids bike sizes +

infographic. Retrieved April 08, 2021, from https://www.icebike.org/the-definitive-guide-

to-kids-bike-sizes-dont-buy-the-wrong-bike/

Montague Bikes. (2021, March 29). Bicycle wheel sizes explained. Retrieved April 08, 2021,

from https://www.montaguebikes.com/folding-bikes-blog/2019/06/bicycle-wheel-sizes-

explained/

USA Cycling. (n.d.). Bike Racing 101. Retrieved April 08, 2021, from

http://legacy.usacycling.org/encyclingpedia/encycstory.php?id=4203#:~:text=The%20main

%20purpose%20of%20junior,such%20as%20height%20and%20power.

Vastbinder, O. (2020, July 22). How to determine the correct saddle height. Retrieved April 08,

2021, from https://www.mantel.com/blog/en/how-to-determine-the-correct-saddle-height

VectorMine. (2020, March 18). Bike Parts. Retrieved April 08, 2021, from

https://www.freepik.com/premium-vector/bike-parts-labeled-illustration-

diagram_7291051.htm

VeloNews. (2015, October 29). Technical FAQ: Junior gear options. Retrieved April 08, 2021,

from https://www.velonews.com/news/technical-faq-junior-gear-

options/#:~:text=Maximum%20road%20junior%20gear%20rollout,700%20X%2023C%20

rear%20tire.

Woodman, O. (2020, December 22). Best road bike PEDALS 2021: 5 top-rated clipless pedals

for your bike. Retrieved April 08, 2021, from https://www.bikeradar.com/advice/buyers-

guides/best-road-bike-pedals/