Specialized Jett 24 bike review

The Jett is Specialized’s response to parents who, when asked what they wanted in a bike for their children, requested a cycle that would fit their children for about 30 months, or three summers. In research, the company discovered that the arms and legs of children aged 5 to 12 grow faster than do their torsos. So Specialized set about creating a bike that was proportional and adjustable, to achieve the perfect fit multiple times over several years.

To put the Specialized Jett 24 to the test for MadeForMums, I enlisted the help of my 8-year-old son, Tyler. Thanks to a brilliant balance bike and 14” Ridgeback bike, Tyler has been riding without stabilisers since he was three. He was then fortunate enough to trial a Specialized Hotrock 20, which he adored. It was a good entry into riding a bike with gears and great fun to ride, but its main drawback was its weight (around 13kg), which Tyler found challenging. So we were really intrigued to discover whether Specialized could keep the weight down while upping the wheel size (from 20 to 24 inches) and gears (from six-speed to eight). He’s going to test the Jett on his commute to school, which takes him on roads, pavements and a few stretches of cobblestones, plus a few excursions to a park.

How did you choose the correct model and size?

As with all bikes, the right model and size is determined by a child’s height, skill level and choice of terrain. Specialized’s sizing guide showed that, at 130cm, Tyler was best suited to the 24” multispeed model, which fits riders who are 109cm to 147cm tall. We were confident this was right since Tyler had ridden his 20-inch-wheel bike for several years and was on the cusp of outgrowing it.
Smaller riders can choose between single-speed or multispeed models with gears in the 20” model – and a 16” model that’s only available in a single-speed version. All sizes and models are fitted with a kids-specific slim saddle and narrower-than-average grips, for increased comfort and control.

How do you fit the bike to your child?

Although you can purchase the Jett online from Specialized, the brand doesn't deliver bikes direct to consumers. Instead, your bike is delivered to your local Specialized retailer (either a Specialized Concept Store or a cycle shop that stocks Specialized bicycles). Shop staff will put the bike together and have it ready to ride, and you’ll leave with all the kit needed to make the recommended adjustments, including two sizes of wrench and two of Allen keys.

Unlike Specialized’s other models, or any other model of children’s bike for that matter, Jett bikes are meant to be adjusted to fit by parents. Once at home, and armed with a tape measure, you download the Jett Fit Tool app and follow the guide to measuring your child, inputting the numbers then adjusting the components of the bike so that it fits your child precisely.

This new concept from Specialized means that with a few measurements, you can adjust specific parts of the bike to the correct position for your child, ensuring that the bike fits perfectly and, crucially, continues to be a perfect fit as your child grows.

What parts of the bike are adjustable – and why?

The extra-long seat post, which at 330mm is about 60mm longer than the typical seatpost on a child’s bike, can be altered to accommodate riders between 109cm and 147cm – a huge range.

The cranks (‘arms’ that connect the pedals to the bike) have two hole-positions so pedals can be set 130 or 150mm from the bike. This allows the space between the pedals to be modified to create hip-knee-ankle alignment, helping to avoid knee pain and improve pedal power.

The handlebars can be rolled forwards to give up to 2cm of extra reach, so can be altered as your rider’s arms grow. There are also spacers (small metal rings) that can be removed or added to raise the handlebar stem 25mm.

Additionally, the short-reach brake levers can be adjusted without the need for any tools, making it easier for children with smaller hands to safely and comfortably engage the brakes.

According to Specialized, these slight but highly effective adjustments increase rider comfort, prevent injuries and improve confidence. The company advises parents to redeploy the fit tool about every six months to keep the bike the perfect fit for their child.

How easy (or difficult) was it to fit the bike to your child?

It was relatively straightforward. The first measurement to input was Tyler’s height, followed by the length of his shin and finally the length of his arm. We then plugged the numbers into the app.

The following screen showed us a list of tools that we would need to set up the bike. These included a 4mm Hex (or Allen) key, a 5mm version, a 13mm torque wrench and a 15mm wrench.

The next page told us the numbered position to move the seat post to, with a short video demonstrating how to loosen the seat collar and adjust the post then tighten the collar, using the provided torque wrench. It was fairly simple to do, though I wasn’t sure what was meant by “tighten the bolt to 6-7Nm” so had to look it up – it relates to a measurement on the wrench.

Next up is a screen showing which of the two positions (long or short) to set the pedals at. The text advises using a 15mm wrench and 6mm Hex key to remove the thread cover. I’m perplexed, as we have a 4mm and 5mm Hex key but not a 6mm version. After some head scratching, we discover we can use the 15mm wrench in place of the Hex key.
Then comes the screen detailing how to set the handlebars to the correct place for your child. The handlebars ‘roll’ into position and there are numbers on the stem to guide you.

Before your child rides the bike, you’re asked to complete a safety test by checking all nuts, bolts and screws have been tightened. While none of this is complex, you do need a certain level of dexterity and strength to ensure everything is secure.

The Fit Tool then advises a test ride outside to ensure the rider can pedal comfortably and start and stop easily. I was fully expecting a wheel to roll off or the saddle to slide down the seat post but was delighted to see the bike held together.

The next slide suggests raising the saddle height by a small amount to help your child pedal more efficiently. That means their feet won’t be flat on the floor while on the saddle so the advice is, if your child isn’t comfortable with just the balls of their feet and toes touching the ground, keep the saddle at the original (lower) height.
The last page summarises your child’s measurements and then suggests two fits – standard and advanced. The final suggestion is to revisit the Fit Tool every six months so you can readjust the Jett bike to fit as your child grows.

How comfortable were you fitting the bike to your child yourself?

Adjusting the bike at home was challenging and more than a little daunting, largely because I’ve never done it before and the safety of my child depended on my ability to do the job of a mechanic. Previously, we’ve spent hours in bike shops while mine and my children’s bikes have been expertly put together then fine-tuned for fit by professional mechanics. I completely trusted the bike shop staff to set up our bikes so they not only fitted perfectly, but they were also completely safe.

Left to my own devices, in my living room, I am not at all confident that I will do a good job. Fortunately, my husband is far more comfortable with the concept of playing bike mechanic and soon got to grips with the app and tools, while I attempted to take accurate measurements of our hugely excited son.

Specialized are keen to point out that the most important factor is rider comfort. The Fit Tool is a guideline to getting the best position for your rider at the time and will not only depend on your child’s measurements but also their confidence level. The main thing to watch for is that your child’s knees aren’t too bent or completely extended while pedalling, they can reach the brake levers and gear shifters comfortably, and see where they are going.

Tell us about the frame of the Jett 24 bike

Like the rest of the bike, the frame has been carefully developed by Specialized to be proportional for your growing child. It’s made from an aluminium alloy, which is strong but relatively light and commonly used in bike frames. Like the forks, the frame comes with a lifetime warranty.

The shape is distinctive, with a low-slung top tube that offers riders plenty of stand-over clearance that makes the bike suitable for children with shorter legs (the extendable seat post gives additional seat height).

There’s plenty of space for the tyres so you could swap to a set of off-road tyres if your child is riding mostly on muddy or uneven surfaces.

It’s also aesthetically pleasing: the tubes are shaped differently, with a narrow, slightly curved top tube and a chunkier, almost square-edged down tube. Together with the burnt orange colour (called Satin Redwood) of the paint, it makes the frame look distinctive and incredibly smart.

Does it have suspension?

No, the Jett doesn’t have suspension, largely to keep the weight down, but it still handles bumps well, thanks to the shock-absorption provided by the aluminium alloy frame and forks and the Pathfinder Sport 2.0” tyres (see below).

On the Jett, Tyler can easily mount kerbs and roll off them without flinching, though he misses the bounciness of his Hotrock, which had front suspension. Still, the lack of suspension forks help keep the weight of the Jett down, which makes the bike lighter and easier to handle.

What are the tyres like?

Impressive. They are Pathfinder Sport 2.0” (that means they are 2 inches wide) and are half an inch wider than those typically used on kids’ bikes. Thanks to their smooth centre line, they roll over tarmac nicely but the wide surface area offers impressive shock absorption and traction in the wet, even when the road to school is littered with slippery leaves. Off-road, the tyres seem to handle grass and dry gravel paths easily.

How lightweight is the bike? Can your son lift it easily?

We were delighted that the Jett 24 lived up to Specialized’s claim that it’s one of the lightest kids’ bikes on the market. At 9.39kg, it’s slightly heavier than the Frog 62, which also has 24” wheels, but while that bike is suitable for children aged approximately 8 to 10 years, the Jett 24 is designed to last children until they turn 12. It’s noticeably lighter than the Hotrock 20 that Tyler’s ridden until now (circa 13kg) and much easier to manoeuvre. On the odd occasion it falls (fortunately not with him on it), Tyler can easily pick the bike up. He can also lift it up kerbs and, when he needs to wheel the bike rather than ride it, for example through our hallway or along a crowded pavement, he finds it really easy to keep the bike upright and under control.

Will the Jett 24 live up to Specialized’s claim it will last for three summers of riding?

Tyler began riding the bike at the age of 8 and the adjustable parts – seat post, pedal cranks and stem/handlebars – were on the lower settings according to his height. Given how much scope there is to adjust the bike, including an extra-long seat post, I imagine it will easily fit him for three years and throughout 30cm growth, as Specialized anticipate. However, as you can see from my scores, I’ve taken a point off as I don’t think it will be looking as smart after a year or two of use because the inevitable chips and scratches to the paintwork are really noticeable due to the bright colour of the frame.

Does the bike feel safe?

Set up correctly, the Jett 24 feels very safe to ride. The frame seems sturdy and durable but not overly heavy or cumbersome, so Tyler is able to fully control the bike, even while turning around sharp bends.
The upright riding position afforded by the handlebar height, which is higher than on his mountain bike, means Tyler’s torso and head are more upright, so he’s got a better view of where he’s going, making the ride safer.

Plus, narrow grips and short-reach brake levers assist with reliable braking – Tyler comes to a controlled stop at every red light and junction on the road, with no skidding. Additionally, the brake levers can be adjusted without the need for any tools, making it easier for children with smaller hands to safely and comfortably pull the brakes.
Finally, extra-wide tyres hug the road, adding to the sense of security.

What do you think of the gears on the bike?

The Jett 24 has 8 gears controlled by a microshift system which sees the rider using thumb and index finger to pull or release a trigger while holding the grip on the handlebar. The action of the 8-speed trigger shifter is light and intuitive – despite having used a grip-shift gear system on his previous bike (whereby you twist the grip with your wrist to change gear), Tyler soon got used to using the trigger shifter.

Tyler enjoys exploring the expanded range (from six gears to eight) and quickly gained confidence in changing gears while pedalling on the road, and soon he only needed to glance down the check he was in the right gear.

Is the Jett 24 bike comfortable to ride?

In a word, yes! Tyler looks immediately at ease on the bicycle and pedals away smoothly and quickly. This is largely due to the upright riding position, which sees his torso and head in line and more vertical – a more natural position to be in than hunched over handlebars.

The wide tyres further up the comfort as they absorb bumps in the road. He’s comfortable riding further and for longer and seems to go faster than on his previous bike.

What’s the steering like?

The steering is very responsive and Tyler’s able to easily control his direction of travel. He doesn’t oversteer and finds turning corners – even tight ones – a doddle. It’s lovely to see his confidence growing as he becomes accustomed to the bike and how it handles.

How easy is it to transport?

I can wheel and lift the bike with ease, so moving it around a playground or lifting it into a car boot is no problem. However, fitting it into a car boot involves using a tool to take off the front wheel, since neither the wheels nor the saddle are quick release. Specialized has done this consciously, reasoning that adjustments will only be needed around growth spurts (so around every six months) but it’s a pain if you have to regularly take off and replace the wheel to fit the bike into your boot.

Does it handle all-terrains?

The Jett is for young cyclists who predominately ride on paved surfaces, although the shock-absorbing tyres and frame could tackle some rough terrain. To make it more suitable for off-roading, you could swap the tyres for knobbly off-roading ones.

Is there an alternative model for a child who mostly goes off-road and rarely cycles on paths or pavements?
Yes! The Riprock has a larger tyre volume which lends itself more to off-road use.

Does the Jett 24 come with mudguards?

No, and that is disappointing, especially at this price point. Even though it’s not designed to be ridden on muddy trails, the Jett can easily tackle wet roads and puddles. Without mudguards, the water and other stuff on the ground gets flicked up onto your child’s face and back. Yuck!

Is there a kickstand?

Yes and it’s a good one - easy to engage and sturdy enough to support the weight of the bike. It’s great for leaving the bike propped up in the local playground, or inside the school gates.

Are there any must-have accessories?

As well as an impressive collection of bikes, Specialized sells everything from saddles to shoes. But the stand-out accessory for kids has to be the brand’s helmets, which feature a magnetic buckle.

It’s a fiendishly clever but super simple idea that makes a huge difference when fitting a helmet to a child, and encouraging him or her to wear it regularly. Instead of a traditional clip that can be tricky for little fingers to release and can pinch skin when pushed together, the magnet buckle simply glides together, allowing easy and secure strap attachment. It was devised by Specialized’s in-house product team as a way to help speed up the transition for triathletes, but it’s been applied to the kids’ helmet line to great effect.

Where can I buy the bike?

It can be purchased directly from Specialized for £439

MadeForMums verdict:

Fusing good looks with clever design, this high quality cycle delivers a ride that’s safe, smooth and so much fun. Jett bikes are uniquely adjustable, allowing parents (with the help of an online fit tool) to fine tune the saddle height, handlebar position and crank length to ensure the bike perfectly fits their growing rider for 30 months, which justifies the price. The Jett 24 is a brilliant ‘next step’ bike, bridging the gap between a first multispeed cycle and an adult bike. It’s perfect for children who cycle mainly on paved surfaces or tarmac rather than muddy trails.