10 Things You Didn’t Know About the Shimano Di2

Jan Poshenko
Written by
Last update:

You Can Customise the Shifting Any Way You Want

Most riders choose the double click down shift when they’re riding with the electronic groupset. This would logically mean that the vast majority of time is spent with the rear derailleur in the small cog. The biggest gears usually are reserved for the last 1% of the ride.

The owner’s manual says you should jump from one larger gear to the next largest gear during an attack. If you’ve done this you’ll know that the time in the larger gear is very brief.

To overcome this, the battery module can be re-programmed to automatically click up through the gears. The percentage of time spent in each gear can be adjusted as desired.

This is a simple procedure and can reduce the tinkering time needed. This is also possible with the front derailleur.

You Can Micro-Adjust While Riding

Have you ever tried to make minor adjustments to your shifting while riding only to find out that shifting is not possible while you're biking? Yeah, us too. Not so with the DI2, however, and it's the coolest thing. You can easily adjust the shifting while riding. No need to slow to the point that you're stopping. Just push the plus or minus button to make adjustment before the gear is engaged and you're set.

Check out this video to get the full scoop (and to see the coolest trick ever):

You Can Shift the Entire Gear Range Single Handedly

This is something that I don’t think any amateur cyclist thinks about when learning about the Shimano Di2 electronic shifting system. If you’re like me, then you were probably captivated by the idea of removing the shifter from your handlebar (or swapping a twisted grip to a flighty paddle).

But what I never knew about electronic shifting is just how much there was to the system. In essence, Shimano created an electronic control center for your bike done.

You may not know what the command center is called, but you can shift the entire gear range with just one hand. I’m not sure why I never thought of that before I purchased my first set of Di2 components, but I guess it wasn’t on my radar.

Don’t be surprised if you yourself, or a rider you know, is still learning how to properly shift the top gear. I’ll be honest; I’m one of those people who fumbles through the shifting on my SRAM eTap.

You Can See the Current Gear Selection on the Bike Computer

For a long time, the limitation of the Di2 shifting was that you couldn’t see the current gear selection on the bike computer.

There were no second chainring or cassette cogs on the left side of the rear Dura-Ace 9070 brake lever to see the gear.

To read the gear, you had to look to the left of the stem, where the Di2 battery slots. This put the readout below your line of sight.

This year, Dura-Ace 9070 comes with a new bracket. This new bracket has the shifters mounted on the inside inboard, so you can see the gear display with a sideways glance.

You’ll barely even know the difference. It’s that good.

You Can't Cross Chain on the Small Chainring

It’s best if you reserve the inner chainring for the steep steeper climbs. Even though you can run the chain directly across, if you have to stop the clock, it will be more efficient to return the chain to the larger chainring.

The Di2 system was designed to work with both road and mountain bikes. Because of that, the inner chainring is only large enough to take a road size chain. It won't take the larger mountain bike size.

Di2 Shifters are Lighter than Mechanical Shifters

Di2 Dura-Ace shifters are 25g lighter than their mechanical Dura-Ace counterparts, even without including the battery. This is possible due to the fact that the electronic shifting system doesn’t need cables and housing.

To make the shift ergonomics the same as the mechanical version, the Di2 shifters are longer than mechanical shifters.

The amazing thing about electronic shifting is that it can be done from the front to the rear, or rear to front. On the down-shifting, it can even go from the front to rear to the middle and then back to the rear.

Shimano claims that the Di2 shifting is as positive as the mechanical version. That being said, some crankset manufacturers don’t make available enough space between the large chain ring and the front derailleur for a mechanical shifter because it reduces the pedaling efficiency. Shimano recommends Di2 option in this case.

Di2 is fully software upgradeable and in case you buy a new bike, you can change the shifting firmware for the new bike.

The best thing about Di2 is that it’s completely wireless.

You can easily program the shifters to set up the rear shifting to work in either mode or both.

You Can Mix and Match Di2 Components from Road and MTB

If you have a Shimano road and mountain bike, you can mix and match the 1x Di2's wiring components and the hydraulic disc brakes. This is opposed to the Campagnolo EPS (electronic push shift) system, which requires all components be Di2.

You Can Wire the Di2 System Any Way You Want

One of the main things that made me jump at the chance to review the new Di2 system was my confidence in the Shimano engineering. They weren’t going to cut any corners; they were going to make the best system on the market for dual control levers, even if it was an expensive and complicated product.

But even I was surprised when the Shimano engineer that was showing me the Di2 system spoke of wiring the Di2’s microprocessor in any way you want. It’s entirely up to you to decide if you want to wire your levers to the system in Series or Parallel.

This is unheard of with any other system, and it’s even heard of to be possible with a Di2 system for double chainrings. Only on the Di2 system for two control levers do you have the option of wiring it in any way you want. Very cool.

Rim and Disc Versions Have the Same Brake Hood Design

You’ve probably spotted the disc brake version of the new Dura-Ace 9000 component groups lurking in the background of Shimano’s shows and media over the last couple of years. It is, after all, the biggest development in Dura-Ace since the introduction of dual-pivot rim brakes. Yet, it seems to have gone largely unnoticed because nobody seems to have asked any questions about it. Maybe this is because everyone’s attention is drawn immediately to the new fancy front derailleur and rear derailleur, or that everyone’s mind has been focused on the new Di2.

Components like the front derailleur and the rear derailleur have a lot going on and require a lot of work. It distracts from the fact that there is also something new at the other end of the bike; something that’s less obvious but is important to understand how the whole Di2 system works.

The Di2 rear brake lever incorporates an entirely new design that is shared with the disc version. Shimano has used the opportunity to completely redesign the caliper and lever system from the ground up. It was a chance to create a completely new and modern look for the rear brake, instead of simply sticking with the same shape that we’re all used to on current groupsets.

There's a Low Battery Indicator

Most wireless bike computers have an accelerometer that tells you whether you should be pedaling or coasting, but the Di2 brain tells you the status of your battery.

You can keep track of the battery level on this Di2 display, and the arrow pointing in the direction of the next shift is a handy extra. If you don’t get enough battery charge on your ride, the arrow will point down, indicating that the computer has moved into a fixed gear mode. If your battery charge is lower than 25 percent and your wheels are removed from the bike, you’ll see a flashing yellow arrow. You can charge your Di2 computer coils with the computer’s charger and batteries with any standard battery charger. Plug your computer’s charger into the computer’s microUSB charge port, and plug the other end into the standard USB port on your computer. When you plug your Di2 computer in, a flashing green light will tell you that the computer is receiving a charge. If you leave it plugged in, an empty flashing green light will appear after the computer is fully charged. If your computer’s power supply gets too hot while charging, the computer will stop drawing power and display the error code 60. If you have a non-USB compatible charger, you can charge your computer batteries with any standard two-amp charger.