Why Di2 and other electric shifters for gravel bikes?

What is electric shifting?

The conventional shifting (gear shifting) function on a road bike uses a shift lever to physically wind up and release the wire connected to the derailleur. This is called “mechanical shifting” in contrast to electric shifting.

In contrast, electric shifting is where the shift lever is “just a button” that sends commands to the derailleur via electrical signals, and the derailleur moves electrically.

Di2" for Shimano, “EPS” for Campagnolo, and “eTap” for Sram are electric shifting components.

Since mechanical shifters are operated by wires, they have the following disadvantages when used on gravel bikes.

1. shifting malfunctions when clogged with mud or other debris
2. heavy and slow shifting

On the other hand, with electric shift components, the shift lever is a switch, so it has the same advantage as the click button on a mouse, which means that "shifting is never heavy.

In addition, shifting is very fast because there is no physical time for the wire to move, and the signal is sent and the shifting can be done instantly.

Electric shifters have all of these attractions, but they do have a weak point. That is the price.

The reality is that electric shifters are not very popular because most parts are not compatible with conventional mechanical shifting components, and because a complete electric component set can cost as much as $2,000 at the lowest.

Electric shifters work well with gravel bikes

Free from wire system problems

Gravel bikes are ridden on rough roads such as gravel and mud roads compared to road bikes. Therefore, if the shift wires become dirty from fine sand and mud bounced back from the road surface, they are prone to problems such as heavy operation and jammed shifting.

Until now, road bikes and cyclocross bikes have dealt with sand and mud by using “cable interiors” where the wires are routed inside the frame, or “top routing” where the front shift is routed through the top tube, but by using electric shifters, you can take measures against mud without having to think about wire routing, etc. By using electric shifters, you can take measures against mud without having to think about wire routing, etc.

Can handle instantaneous shifting.

When riding on rough roads such as gravel, the road conditions change more rapidly than on paved roads.

On paved roads where road bikes are used, the road visibility is good to some extent, and the gradient changes are gentle because the road is basically designed for cars.

However, on unpaved roads such as forest roads and muddy roads, the transformation of road conditions is rapid because they are not well maintained. Shifting downshifts at a slight bump, and upshifts on a downhill, make shifting as busy as on a MTB.

Considering such roads where gravel roads are ridden, there are many scenes where electric shifters that can shift gears at once and instantaneously are beneficial.

Di2’s “Synchro Mode” allows you to shift with a single lever, even on a front double.

Shimano Di2 has multiple settings for shifting operation.

1. Normal mode
2. Synchronized shifting (shifting is done by right shifter only; FD automatically shifts depending on RD position)
3. Semi-synchronized shifting (shifting RD to the appropriate gear ratio according to FD shifting)

Of the two, synchronized shifting is operationally the same as the front single, as all gear changes can be made only with the right shifter.

The shifting mode can also be changed with the Junction A unit, so it is possible to switch to synchronized shifting when entering gravel, for example.

Does front single need electric shift?

Front singles are where electric shifters live.

The advantage of electric shifting is stable shifting even on rough roads, but it is the front shift where the wires tend to be exposed under the BB that needs to be protected against mud. However, many gravel bikes are now available with a front single model, which may not have a front shift.

The advantage of electric shifting even on a front single is that it allows for instantaneous shift changes. This is why Shimano’s gravel component GRX has a Di2 model.

For example, on a gravel bike with a single front wheel, there are times when you need to shift several gears at once, sometimes as many as four or five gears. This is the case, for example, when you are on a forest road and suddenly have to climb from a downhill slope.

In such a case, with mechanical shifters, you need to shift 2 gears x 2 times, and in some cases, you may not be able to shift properly and end up in a heavier gear, losing your balance and falling off the bike. However, with an electric type such as Di2, you can shift as much as you keep pressing the shift button, allowing for smooth and large gear changes.

With a front double, you can lower the gear ratio all at once by dropping from outer to inner, but with a front single, you have to make “lots of shift movements” only at the rear, which is where the advantage of electric shifting comes in.