Cobra King RadSpeed Junior Driver: How to Size and Choose the Right One

By Ethan Brooks

Updated November 2026

A cobra king radspeed junior driver is built for kids who need a lighter, more forgiving club than an adult driver. This guide shows you how to match the club to your child’s height, swing speed and grip size, then how to check the fit before you buy. Most of the decision comes down to length and flex, so start there.

Step 1: Measure Your Child for Length

Length is the first number to get right. A driver that is too long forces a child to stand too far from the ball and swing out of posture, while one that is too short cramps the swing and limits distance. Use height as your starting point, then confirm with a simple check at home.

Shopping for one? See our guide: 5 Best Cobra King RadSpeed XB Junior Driver Options for Young Golfers (2026).

Have your child stand barefoot with a relaxed posture and arms at their sides.
Measure from the floor to the top of the wrist crease. This is a common reference point for junior club fitting.
Compare that number to the length chart the manufacturer publishes for the RadSpeed junior line. Charts vary by model, so check the one tied to the exact club you are considering.

Step 2: Match Shaft Flex to Swing Speed

Flex controls how much the shaft bends during the downswing. A shaft that is too stiff makes the ball fly low and right for many kids, while one that is too soft can cause a high, ballooning shot and loss of control. Junior flexes are typically labeled by size or as junior, senior-junior and similar categories, so read the labels carefully.

If your child swings slowly and struggles to get the ball airborne, a more flexible shaft usually helps. If they already hit hard, straight shots, a firmer option may suit them better. Watching a few swings from the side and noting where the ball lands is a practical first check, though a qualified club fitter can give a more reliable answer.

Step 3: Check Swing Weight and Grip Size

Swing weight affects how the club feels through the swing. A heavier head can build confidence for some kids, but it can also slow down a smaller swing. Ask your child to swing a few clubs of different weights and notice which one lets them keep their tempo.

Grip size matters just as much. A grip that is too thick makes it hard to close the hands and square the face. A grip that is too thin can cause the hands to roll over the club. Your child’s fingers should wrap around the grip with the last finger of the top hand fitting comfortably without pressure.

Quick sizing checklist

Measure height and wrist crease, then find the matching length on the chart.
Confirm the flex label matches your child’s swing speed and ball flight.
Test two or three weights and choose the one that keeps tempo steady.
Check that the grip fits the hands without forcing a strong or weak position.
Have the club reviewed by a professional fitter if you are unsure after these steps.

Common Mistakes Parents Make

Buying a driver a size up so the child can “grow into it,” which hurts posture and swing consistency now.
Relying only on age instead of height, since kids of the same age can differ a lot in size.
Ignoring grip size and letting the child choose a club based only on color or looks.
Skipping a test swing before purchase, especially when buying online.
Assuming the club will need no changes as the child grows. Length and flex should be rechecked every season or two.

Recommended Gear

A simple measuring tape and a short practice mat help you check length and watch swing path at home. View on Amazon

A junior-size grip sizing kit lets you compare thicknesses before you commit to a club. View on Amazon

A lightweight junior golf bag keeps the driver and other clubs organized on the course. View on Amazon

FAQ

How do I know if a cobra king radspeed junior driver is the right length?

Measure your child’s height and wrist crease, then compare the result to the manufacturer’s length chart. The child should stand at a comfortable distance from the ball with a relaxed, upright posture.

Should I choose flex by age or by swing speed?

Swing speed and ball flight are more reliable than age. Two kids of the same age can need very different flexes depending on how hard they swing.

When should I replace a junior driver?

Replace or re-fit the driver when your child outgrows the length or grip size, or when their swing changes enough that the shots no longer fly straight. Many families recheck sizing every season or two.

Conclusion

Getting length, flex, weight and grip right makes a junior driver far easier to swing and enjoy. Measure carefully, test before you buy, and recheck as your child grows. A professional club fitter can confirm your choice if you are still unsure.

Ready to choose one?

About Ethan Brooks

Ethan Brooks is part of our editorial team and reviews and edits our junior golf gear guides, checking product details against manufacturer specifications and owner feedback.

About the author

Ethan Brooks

Ethan Brooks writes reviews and buying guides for Junior Golf Results.