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Specialized Jett kid’s bike gets Retul treatment & app based fit tool for the perfect fit

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Making a great kid’s bike can be pretty challenging. Frequent growth spurts make finding the perfect fit a moving target. At the same time, the bikes need to be light enough that they’re actually fun to ride for small cyclists. Then there’s the components themselves, which often require kid-specific sizes to provide better control.

When Specialized set out to design their newest kids’ bikes, they started with the parents. When asked, most said that they wanted a bike that they could get at least three summers out of with an ideal fit. That works out to about 30 months – which doesn’t sound like much, but given how quickly kids can grow, it’s more than most kids’ bikes offer for an ideal fit.

Specialized Jett kid's bike fit

To figure out what that meant in terms of kid-specific fit, Specialized turned to their experts at Retul in Boulder, CO. Their fit experts gathered data from their own kids in order to analyze just what made for a comfortable kid’s bike.

Specialized Jett kid's bike saddle adjustment

The result is the Specialized Jett. A kid’s bike with an impressive range of adjustability that claims to deliver that 30 months of growth into the ideal fit range.

What makes the Jett different?


Specialized Jett kid's bike seatpost

Most kid’s bikes are adjustable, so what makes the Jett so special? Basically, it comes down to a wider range of adjustability coupled with a clever app and sizing labels that make it super easy for parents to properly set up the bike.

Using the Jett Fit Tool app, you start by measuring the height of your child along with the length of their shins and arms. That provides the starting point for the fit, and the app then guides you through all of the exact settings on the bike.

Specialized Jett kid's bike seatpost markings

Adjustements start with the seat post which claims to be 60mm longer than most typical seat posts on kids’ bikes and also has a shorter minimum insertion. Combined with the fact that you can bury the post all the way to the bottom bracket, you end up with a seat post range that is as long as possible. Better yet, the seat post has clearly labeled numbers which match up to the app – so instead of having to measure out a certain height, you just line up the number with the seat post collar.

Specialized Jett kid's bike handlebar Specialized Jett kid's bike handlebar

Up at the front, the Jett features handlebars with only 5° of backsweep. That’s because the bars are meant to be rotated backwards to fit riders with shorter arms, and it will keep their wrists at a proper angle. Again, clearly labeled handle bar positions are lined up with the mark on the stem based off of the app instructions – no more guessing where the bars should be.

Specialized Jett kid's bike grips and brake lever Specialized Jett kid's bike tires

While not unique to Specialized, the bikes all have smaller diameter grips and short reach brake levers to make using the hand brakes easier for all kids. All sizes of the Jett include hand brakes and 2.0″ wide Pathfinder tires.

Kid-Specific Q-factor?

Specialized Jett kid's bike q-factor

While many parents might not even know what q-factor is, their child will still benefit from a narrower q-factor meant for kids. Part of Specialized’ research found that most kids bikes use cranks that include q-factors that are too wide – meaning the distance from the outside to outside of each crank arm is too far apart for smaller hips. The Jett uses a narrower q-factor crank with a narrower saddle to prevent kids from having to rock their hips from side to side while pedaling.

Specialized Jett kid's bike crank adjustment

The multispeed Jetts also see more adjustments at the cranks, with two pedal positions.

Models & Sizes

Specialized Jett kid's bike size range

You’ll find the new Jett in four different models and in three wheel sizes. The smallest is the Jett 16″ which is only offered in single speed. Then the Jett 20″ comes in both a single speed and 7-speed option, followed by the Jett 24″ which is 8-speed only. The bikes have A1 Premium butted alloy unisex frames with claimed weights of 8.76kg or 19.3lbs for the Jett 20″ MS, or 9.39kg/20.5 lbs for the Jett 24″ MS.

Pricing starts out at $450 for the Jett 16 SS, then $475 for then $475 for the Jett 20″ SS, $520 for the Jett 20″ MS, and $580 for the Jett 24″ MS.

Recommended height range:

  • Jett 16” SS: 95cm – 121cm
  • Jett 20” SS or Jett 20” MS: 102cm – 132cm
  • Jett 24” MS: 109cm – 147cm

Children’s bike progression

Specialized Jett kid's bike progression

Keeping it in the family, Specialized gives a suggested bicycle progression from balancing on a Hotwalk to shifting on a Jett or Riprock. Keep things fun, and your child will be upgrading to a full size bike before you know it!


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2 years ago

Really like the design on the bigger model. They should build an adult sized one with the same design language (and fenders).

2 years ago

I am so glad they specced trigger shifters. When I got my kid a derailleur bike, it had a Shimano twist shifter and those are so awful. I rigged up a test for him to try SRAM vs Shimano, both for triggers and twist, and SRAM trigger was the easiest for him, but both twists were unworkable.

2 years ago

Really? No mention of how the Jett is offered direct to consumer?

2 years ago
Reply to  Zach Overholt

Probably a strategic omission on their part for sure.
The whole kids fit app is PERFECT for at home consumers assembly and sizing up the self built bikes so kudos there. Even if it does side step the LBS completely in the process.
The real kicker is if “connect you to local dealers ready to help” will be expected of anyone carrying specialized free of charge. Especially if they don’t have any stake in the transaction besides building relationships. If bike and and all accessories are purchased direct, what’s left for the LBS?

2 years ago

They didn’t pay much attention to the retul data if they ended up with cranks that long.
My 7yr old asked if it was a BMX because of the bars.
I can see the concept being useful for the non cyclist parent, but I wouldn’t want to hamper my girls riding by trying to get longer out of a bike than was ideal.

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