Build a Di2 bike | BetterShifting

Want to build a new Di2 bike? Great – it's a genuinely satisfying job, and not a hard one once you understand the basics.

But before you start buying parts, there are a couple of things you need to decide on: what kind of bike is it, 12-speed or 11-speed, and road, gravel, MTB or time trial?

This page walks you through it in order: first the planning, then the build itself.

Scroll to the section that matches your build, where I've linked every relevant guide.

Before you buy parts: plan your build

Most build problems aren't installation mistakes – they're planning mistakes. The wrong wire length, an incompatible derailleur, or the wrong groupset for your budget.

Decide on these things first.

What parts do you need to build a Di2 bike? – start here. The complete shopping list, explained.
Dura-Ace vs Ultegra vs 105 Di2: what's the difference? – pick the right tier before you spend.
Cable routing, wire lengths and wiring – getting wire lengths wrong is something that can really mess up your build.
12-speed road bike components and wiring – example of a full 12-speed road build.
Understanding Di2 derailleur specifications – capacity, tooth limits and what your drivetrain can actually run.

Required Tools

You don't need much that a home mechanic doesn't already own. Beyond your usual workshop kit, have ready: a Di2 plug tool for seating connectors, a torque wrench for derailleur and lever bolts, the correct charger or charging cable for your battery, and a way to run E-Tube – either a Windows PC, or the E-Tube Cyclist app on your phone.

For diagnostics and firmware updates on a fresh build, the SM-PCE02 is handy, but definitely not essential for home builds.

Di2 basics

Whatever you're building, these apply.

1x12-speed MTB / Gravel Di2

These bikes are different from the 2x12-speed systems. They're fully wireless, with the battery mounted in the derailleur. You'll need a derailleur, the BT-DN320 battery, and a compatible shifter.

2x12-speed Road / Gravel Di2

This is 12-speed semi-wireless Di2 – the road Dura-Ace, Ultegra, 105 and GRX groupsets all live here. Wireless shift levers, derailleurs wired to a seatpost battery.

12-speed Time Trial bikes

Building a 12-speed TT bike? The 2x12 guides above all apply, plus this one:

Build a 12-speed Di2 Time Trial bike

11-speed / 10-speed Di2

Building an MTB or road/gravel bike from 11-speed parts? They're no longer in production, but there's plenty out there on the second-hand market.

Most of the guides below apply to 10-speed Di2 too – though I don't recommend building a 10-speed bike from scratch at this point.

Sourcing second-hand parts

Since 11-speed is out of production, most builds start on the used market. These two pages will save you from buying the wrong thing – or a worn-out one.

Upgrading an existing Di2 bike

Not building from scratch, but want more from the bike you've got? Adding satellite shifters, or moving an older bike forward a generation, is a great project.

Stuck on something?

If a component won't behave during the build – a derailleur that won't set up, a shifter that won't pair – the Fix your Di2 bike page covers the common ones.

Still stuck? Send me an email or WhatsApp message and I'll help you through it.