Trek Superfly 20in kids’ bike with Di2 upgrade

Trick bike for child of a bike shop store owner

BikeRadar recently put a bunch of 20in kids’ bikes against each other, and the relatively expensive Trek Superfly 20in came out on top. While our young test riders loved the bike, their main complaint was with the gear shift quality, an issue that affects most geared kids bikes.

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So what if there was unlimited budget? Electronic gears! In practical terms, the price is enough to stop it being a reality, but electronic gears make lots of sense for children who lack the hand strength to shift easily.

This led Mark Rowling, owner of Sydney-based Turramurra Cyclery to build his six-year-old son something special. The store has a reputation for building often extravagant Pinarellos, and this Trek is certainly in a similar league. Rowling took a stock Trek Superfly 20 and turned it into a AU$2,999 mini dream bike.

Ultegra Di2 would have worked just as well, but Dura-Ace just ensures few are going to copy this!
Ultegra di2 would have worked just as well, but dura-ace just ensures few are going to copy: ultegra di2 would have worked just as well, but dura-ace just ensures few are going to copy
David Rome / Future Publishing

Ultegra Di2 would have worked just as well, but Dura-Ace just ensures few are going to copy this!

Obviously the biggest upgrade is the Dura-Ace 9000 11-speed Di2, but it wasn’t just a matter of slapping on a new shifter and derailleur. To fit the 11-speed cassette, the rear hub was replaced with a matching Dura-Ace hub and laced back to the stock rims.

The shifter is a R660 Di2 Climbing shifter using E-tube wiring technology. With two buttons on a single pod, it offers the lightest action shifting on the market.

A Pinarello Di2 adaptor and a drill - that's how this battery was mounted
A pinarello di2 adaptor and a drill – that’s how this battery was mounted: a pinarello di2 adaptor and a drill – that’s how this battery was mounted
David Rome / Future Publishing

A Pinarello Di2 adaptor and a drill – that’s how this battery was mounted

The Di2 wiring has been routed internally; Rowling drilled into the frame (goodbye warranty!) and then secured the battery to the down tube with a Pinarello adaptor plate and heavy-duty adhesive tape.

With a quick-release on the back, the front has been replaced with a matching Dura-Ace skewer too.

To further drop the weight and improve the aesthetic, the stem is slammed and the steerer cut flush.

New tires and brakes
New tyres and brakes: new tyres and brakes
David Rome / Future Publishing

This Superfly 20in was also give new tyres and brakes

The brakes on kids bikes often leave a little to be desired and so have been replaced with Shimano’s DXR levers and V-brake callipers, something from the company’s performance BMX racing range.

The stock cranks remain, with few options available in the 140mm length. To drop a little weight and improve the chainline, the bottom bracket was replaced with a higher-end square taper unit. Further reducing weight and increasing the speed is a pair of 20in Schwalbe Durano slick tyres.

A Bontrager XXX bottle cage. Well, why not?
A bontrager xxx bottle cage. why not? : a bontrager xxx bottle cage. why not?
David Rome / Future Publishing

A Bontrager XXX bottle cage. Well, why not?

Completing the build is a Bontrager XXX bottle cage, something that alone costs more than any department store bought kids’ bike.

With the bike weighing in at 7.9kg, it doesn’t sound as though this project is over yet. Rowling is keen to drop the weight further, and with the saddle, seatpost, stem, handlebars all stock there’s plenty of space to bump this one well above its current $2,999 price too. 

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Obviously this isn’t the first tricked out kids’ bike. If you’ve done something special to your kids’ bikes, tell us in the comments below.