Smith Sidekick Jr. Youth Bike Helmet Review

The Smith Sidekick Jr. MIPS is proof that not all kids’ helmets are created equal. If you’ve ever struggled to find a helmet that fits just right, stays put, and holds up to the demands of an active young rider, the Sidekick Jr. was designed with exactly that in mind.

From its mountain bike-inspired styling to its impressively adjustable fit system, the Sidekick Jr. has a lot to love. Young riders will appreciate the look and comfort while parents will love its ease of use and MIPS protection. Whether your young rider is tearing up singletrack, cruising the neighborhood, or tagging along in a Mac Ride or ShotGun seat, the Sidekick Jr. has them covered, literally and figuratively.

Who Is the Smith Sidekick Jr. Best For?

The Sidekick Jr. is the best choice for parents who want a helmet that fits right from day one. With four points of adjustability, including the dial adjust, locking ear sliders, chin strap, and the rarely seen vertical height adjustment, it is more likely to fit your child’s head straight out of the box, without the frustration of trying on helmet after helmet looking for the right match.

Its mountain bike DNA also makes it the go-to for young riders hitting the trails, whether on their own bike or riding along in a Mac Ride or ShotGun seat. That said, the Sidekick Jr. is equally at home on pavement, so if you want one helmet that can do it all, this is a strong pick.

Sizing

The Sidekick Jr. comes in two sizes: the Youth X-Small (48–52cm), which Smith recommends for ages roughly 4 to 8, and the Youth Small (51–55cm), recommended for ages 8 to 12. That said, age ranges should be a very rough starting point.

Our main testers were 4 and 5 years old with larger than average heads, and both fit comfortably in the Youth Small. As with any helmet, we strongly recommend measuring your child’s head circumference before ordering rather than relying on age alone. This guide walks you through exactly how to do it.

What Makes the Sidekick Jr. Stand Out?

Adjustability: Where the Sidekick Jr. Truly Shines

When we compare the Sidekick Jr. to its competitors (more on that below), adjustability is where it pulls ahead by the most. While most youth helmets offer two or three points of adjustability, the Sidekick Jr. offers four: the dial adjust, the vertical height adjustment, the locking ear sliders, and the chin strap. Most helmets include a dial adjust and chin strap as standard, so it is really the vertical height adjustment and locking ear sliders that set the Sidekick Jr. apart.

Dial-adjust Internal cage with Rear Cage Cup

The rear portion of the Sidekick Jr.’s internal cage has a vertical “cup” component that wraps up and around the back of the skull, rather than just running in a flat horizontal line beneath it. This cup cradles the occipital bone, the rounded, protruding part at the base of your skull, which helps anchor the helmet in place and prevents it from rocking forward or sliding back during a ride. Most kids helmets, even the similarly priced Giro Fixture II MIPS, do not include the cup.

Never heard of a cage cup before? If you have a quality adult bike helmet, go take a look at it. Odds are it has one, but it is typically omitted in kids’ helmets to help keep costs down.

Vertical Height Adjustment

The Sidekick Jr. also distinguishes itself by offering three height settings so you can position the cage cup in exactly the right spot for your child’s head.

When the cage cup is properly seated beneath the occipital bone, the helmet sits lower and more securely, and the cage provides just enough upward pressure to keep everything snug and stable.

Adjusting the height simply requires you popping out the top of the cage cup and then reinserting it into the provided insertion points.

This doesn’t change how deep the helmet sits on the head. It just allows the cage to get a better “grip” on the unique shape of your child’s skull.

This kind of vertical adjustability is rare in kids’ helmets and makes a real difference for fit.

360° Internal Cage

While common in helmets at this price point, the Sidekick Jr.’s 360° cage wraps around the entire head. After testing over 70 different kids’ helmets, we have seen time and time again the benefits of a 360° cage for both comfort and fit.

When the dial is tightened, the cage doesn’t just push inward from the back. It also contracts partially from the sides for a more even, secure fit. The cage across the front stays stationary but provides a smooth mounting surface for the pads, keeping them from pressing into ventilation channel ridges or blocking airflow.

Locking Ear Sliders

The Sidekick Jr. uses locking sliders that let you reposition the ear straps to line up perfectly with your child’s ears and lock them in place, so you don’t have to readjust every single ride. Standard ear sliders are a common frustration point for parents because they easily shift out of position and throw off the fit of the helmet. The locking mechanism on the Sidekick Jr. solves that problem entirely.

It is worth noting that the Giro Fixture II MIPS and Lazer Finch Kenticore take a different approach entirely, as use fixed, sewn-in ear straps instead of sliders. When fixed straps line up well with your child’s head, they are clean and simple. But if they don’t, there is nothing you can do about it.

The Sidekick Jr.’s locking sliders give you the flexibility to get the fit right and keep it there.

Additional Sidekick Jr. Features

MIPS Protection

The Sidekick Jr. includes MIPS (Multi-directional Impact Protection System) as a standard feature, not an optional upgrade. MIPS consists of a thin black plastic inner cage attached to the helmet’s foam with small rubber anchors.

In the event of an angled impact (the most common type in bike crashes), those anchors flex slightly, allowing the outer shell to rotate around the head while the inner cage and your child’s head stay more stationary. The result is reduced rotational strain on the brain and neck. Smith also took the time to make sure the MIPS anchors on the Sidekick Jr. are covered by the helmet pads.

Exposed MIPS anchors are notorious for catching and pulling long hair, so this is a huge bonus.

Ventilation

With 12 vents connected by internal air channels that run beneath the MIPS layer, the Sidekick Jr. is one of the better-ventilated helmets in its class. The air channels originate at the front of the helmet, right near the forehead, and guide airflow from front to back across the top of the head.

Combined with the large vent beneath the visor, it creates a noticeable airflow effect even at lower speeds. Riders who tend to run hot will appreciate the extra attention Smith put into making this helmet breathable.

Construction and Comfort

The Sidekick Jr. uses in-mold construction, which fuses the outer shell directly to the EPS foam beneath it. This creates a stronger, more rigid helmet without adding extra weight, and it’s noticeably more durable than helmets where the outer shell is glued on separately.

The comfort liner pads are soft and sweat-absorbing, with sealed edges to help prevent dripping. Because the 360° cage provides a smooth, rib-free surface throughout the interior of the helmet, the pads lie flat and don’t compress into ventilation ridges, something that can be a real comfort problem in helmets without a full-wrap cage.

Smith Sidekick Jr. vs. The Competition

We put the Sidekick Jr. head-to-head with two of its closest competitors at a similar price: the Giro Fixture MIPS II and the Lazer Finch Kenticore.

Adjustability: The Sidekick Jr. wins this category outright. With four points of adjustability versus two or three on its competitors, it has the ability to fit more heads better. The Giro Fixture II doesn’t include a cage cup, which means less rear grip on the occipital bone. Neither competitor offers height adjustment on the internal cage.

Anti-Rotational Protection: All three helmets include anti-rotational impact protection, which is great to see at this price point. The Sidekick Jr. and Giro Fixture II both use MIPS (Multi-directional Impact Protection System), while the Lazer Finch uses Kenticore, a similarly designed system intended to reduce rotational forces on the brain during an angled impact. Any of the three gives you solid protection in this area.

Ear Straps: The Giro and Lazer both have sewn-in, fixed ear straps. When they fit your child’s head, they’re great, clean and simple. But if they don’t line up well, there’s nothing you can do. The Sidekick Jr.’s locking sliders let you dial in the ear strap position.

Ventilation: The Sidekick Jr. and Lazer Finch both channel airflow from the front of the helmet near the forehead, where it does the most good. The Giro Fixture II’s ventilation channels start further back and don’t connect the vents as efficiently, making it noticeably less breezy on warm days.

Buckle: The Lazer Finch has a magnetic Fidlock buckle, which is pinch-free and very easy to use, a genuine advantage over the standard buckles on the Sidekick Jr. and Giro Fixture II. If buckle ease is a top priority, especially for squirmy younger kids, this is worth considering.

Pads: The Lazer Finch has slightly thicker pads than the other two.

Depth: The Giro Fixture II is slightly deeper than the others, which may be a better fit for kids with taller head profiles.

Smith Sidekick Jr. Bottom Line

If fit is your top priority, and it should be, because a helmet that doesn’t fit correctly can’t protect correctly, the Smith Sidekick Jr. MIPS is the standout choice in its price range. Its four-point adjustability system, including the unique cage cup and vertical height adjustment, gives it an edge over the competition that’s hard to overstate.

Add in the mountain bike-worthy design, excellent ventilation, standard MIPS protection, and in-mold durability, and the Sidekick Jr. earns a top recommendation for young riders from roughly ages 4 to 12, on any terrain.

To view an a full selection of helmets, check out our 10 Best Kids Helmets page.

FTC Disclosure: Affiliate links are included in this review.  No monetary compensation was provided for this review.  The product reviewed was supplied by Smith Optics. All opinions and images are that of Two Wheeling Tots LLC.  All content and images are copyrighted and should not be used or replicated in any way. View our Terms of Use.