Di2 on a kids' bike? DIY upgrade to a Trek Superfly 20in

Trick bike for child of a bike shop store owner

The Trek Superfly 20in kids' bike is a popular choice among young riders. It's not available in the UK, but it recently scored highly in a 20in kids' bikes round-up conducted by BikeRadar Australia and some junior test riders. 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.

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 (approx £1,658) mini dream bike.

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
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

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: 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

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 tyres and brakes: new tyres and brakes
New tyres and brakes: new tyres and brakes

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. why not? : a bontrager xxx bottle cage. why not?
A bontrager xxx bottle cage. why not? : a bontrager xxx bottle cage. why not?

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 some more, and with the saddle, seatpost, stem, handlebars all stock there’s plenty of space to bump this one well above its current AU$2,999 price too. 

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.

David Rome

Former Editor, Australia
Dave was the editor of BikeRadar Australia until early 2016.
  • Discipline: Mountain, road and cyclocross
  • Preferred Terrain: Fast and flowing singletrack with the occasional air is the dream. Also happy chasing tarmac bends.
  • Current Bikes: Trek Fuel EX 27.5, SwiftCarbon Detritovore, Salsa Chilli Con Crosso
  • Dream Bike: Custom Independent Fabrications titanium, SRAM Etap and Enve wheels/cockpit
  • Beer of Choice: Gin & tonic
  • Location: Sydney, Australia

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