MakeShift: Security Analysis of Shimano Di2 Wireless Gear Shifting in Bicycles

Honestly, routing the cables through the headset introduces so many tight bends, I suspect you'll get better long-term reliability with wireless. Plus, there are no connections to make waterproof aside from the battery.

You're talking about charging... monthly? With a system that gives clear warnings early that you're low on battery?

I'm already charging my GPS, headphones, bike lights, etc. regularly. This has been an absolute non-issue to me.

If the battery lasted for 100 miles, sure. But I'm getting ~1000 miles a charge.

It simplifies installation and getting a reliable, comfortable shifting setup, yes. Installation is simplified, especially in the case of internal and headset routing, which is something the target audience would deal with in case of cable-actuated derailleurs. Changes requiring adjustments over time due to the cable wearing out or stretching are eliminated, simplifying maintenance, both during and in between rides. On drivetrains with front and rear derailleurs, it has an optional adjustable algorithm that shifts both together for you and chooses the best gear combinations as you press up and down, simplifying operations. Auto-shifting is available on some models. There's more possibilities to put the shift buttons in the most ergonomic place, or even put them in more than one place, simplifying setting up your bike for comfort. That it doesn't simplify fixing your derailleur in the middle of a ride is even debatable. Yes, the radio or battery could fail, but on the other hand it is less prone to go out of adjustment.

Also it has one killer feature and everyone that tries one also raves about how well it works. You know those little ramps stamped into the side of the sprockets on a cassette, that the chain moves up and down on as you change gears? Di2 delays your shift precisely until the start of a ramp, which makes shifting faster and works much better under load. That crunch and possible stuck chain when you shift to start a climb is basically eliminated.

Is it something a bikepacker will choose? Probably not. Is is something attractive to many other types of cyclists and simpler to install, use and maintain in ways they care about? Yes.

The answer is YES, and this type of shifter is a favorite among mountain bikers whose reliability needs and "field conditions" are already much more challenging than your average biker.

There are plenty of examples of situations where a wireless setup simplifies things.

I used to put wired speed/cadence sensors on my bike. Now I just zip tied two BLE gyros to the wheel and crank and things are vastly simpler.

> What ever happened to measuring speed, cadence and pedal force using your body and mind?

How do you export a time series of that?

We can do that. (I barely “measure” in the sense that I’m lazy and just pedal slowly, haha).

But there’s a well established community of really hardcore bicycle hobbyists. The folks paying a couple thousand dollars for shifters want fancy stuff. Some want graphs and numbers. shrug

Yes, but for racing bikes, which are the target market for wireless shifting in 2025, the efficiency losses of an internal hub are a non-starter.

The casuals whose bikes haven't seen a wrench since they were assembled aren't buying wireless groupsets. For them: we're in agreement about belts and internally geared hubs.

Automatic shifting has yet to prove itself to be more than a curiosity. A 20-something year old Autobike came into the shop I was wrenching in. It still worked shockingly well for being covered in rust. In good shape it would be an entirely adequate solution, if only it solved a problem anyone had.

My money is on e-bikes entirely supplanting any demand there may have ever been for automatic shifting on a bicycle. The motors have enough oomph that they make a lot of shifts unnecessary if you're not looking to maximize speed/battery life/whatever.