Summary of gear combinations to avoid "chain tucking" on road bikes

Why is chain tucking deprecated?

Tucking causes extra wear and tear on parts.

Major component manufacturers such as Shimano deprecate the use of combinations where the chain is tucked. The reason for this is that the chain is subjected to lateral force, which leads to unnecessary wear and tear on the chain and sprockets.

The chain and sprockets are not the most expensive components in a road bike, but they are still consumables and should be used for a long time.

Because they lose pedaling power.

When a chain is slung, the chain line is naturally slanted. If the chain line is slanted, power will be lost.

To make it easier to understand, let’s imagine a “tug of war”. The chain of the road bike is the rope, the front is you, and the rear is your opponent.

In a tug-of-war, the most power is transmitted when you are in a straight line. When both of you are in a straight line, the force is balanced, so if you can pull harder than your opponent by putting in more effort, such as lowering your back, you can win. On the other hand, in tug-of-war, if you move even a little to the side, the force in the vertical direction will be weakened and your opponent will pull you all at once.

This is exactly what happens when a chain is slung over a sash, and the force in the straight line direction escapes outward, resulting in power loss.

If you want to know about chain tucking, know the main zone and dead zone of your gear

In most road bikes, the pattern is two front chainrings and eight to eleven rear sprockets, and chain tucking occurs when you enter the dead zone of the rear sprocket against the front chainring.

Main Zone Concept

The center of the rear sprocket (the middle gear) and one front and one rear (or two depending on the number of rear pieces) are the main zones.

This is because the front and rear gears of a road bike are generally built centered on a line that connects them in the middle.

For example, if you have a Shimano SORA 9s, it is a 9-speed bike, so the center of the rear sprocket is 5th gear and the main zone 4th to 6th gear. These two non-center gears (4th and 6th) will also be the cues for shifting the front.

The concept of a dead zone

The dead zone of the rear sprocket can be easily determined because it is a “non-main zone.

In the case of Shimano’s “sora 9s” road bike components, the main zone is 4th to 6th gear, so 1st, 2nd, 3rd, 7th, 8th, and 9th gears are candidates for the dead zone.

However, not all of these six are dead zones, and the first, second, and third speeds, which are closer to the inner side, are not dead zones when the front is inner.

On the other hand, 7th, 8th and 9th gears, which are closer to the outside, are not dead zones when the front is on the outside.

The table below shows the results.

In sora’s example, the following combinations are the ones that will not cause chain multiplication.

1. from 1st to 6th gear when the front gear is inner gear
2. from 4th to 9th gear when the front gear is outer.

How to change gears without chain tucking.

Let’s speed up the gear combination.

First of all, let’s find out how fast your road bike can go with which combination.

Let’s take a Shimano SORA 9s as an example, a road bike with 25c tires, running at an average cadence of 80 rpm.

The gear combinations and speeds are as follows

Let’s get the main zone up to speed.

Then pick up the speed in the main zone of this road bike.

The gear ratio of a city bike is 2.285, so with inner gears, you can ride out lighter than a city bike in the main zone alone.

If you look at the high speed range, you can reach a maximum speed of about 32km/h in the main zone alone. This is enough speed unless you are racing, so if you are a regular rider, you don’t need to pay attention to chain tucking as long as you keep in mind to ride in the main zone.

Simulate a combination that runs only in the main zone.

Once you have the speed in the main zone, let’s simulate actually shifting on the road bike. The speed is based on the assumption that you will be riding on level ground.

Start out in “inner and rear 4th gear”. From there, upshift the rear to 5th and 6th gear to get to 6th gear.

If the speed exceeds 22km/h, it will start to idle, so before it does, downshift two rear gears to 4th gear, and then shift the front to outer. Be careful not to reverse the process, or the chain will fall off more easily.

From here on, all the combinations (4 to 9 speeds for the rear) are usable gear combinations for the outer, so just shift up and down according to your speed.

If you are not used to shifting from the “inner 6th gear” to the “outer 4th gear”, you will feel a little slowed down and even if you are able to shift smoothly, you will feel a little heavy because the gear ratio suddenly goes up by 0.4, whereas it has been going up by 0.2 so far.

If you are riding at a high speed, you can quickly pick up the pace with a little effort, but if you find that you are slowing down more than you expected, you should temporarily drop to “outer third gear” to pick up the pace.

If the bike feels too heavy even in 3rd gear, it is better to drop the front to the inner gear.

Learn to cue the front to shift

As you can see, the front gear is the starting point for chain slap on a road bike. In other words, you just need to remember the rear gear (cue) that is just enough to avoid chain splicing.

As we saw earlier, in the case of sora 9s, 4th and 6th gears are the cues, so remember to shift the front gear when you reach this point.

The tips to remember are as follows.

• At speed up -> 1, 2, 2-1 (rear up twice, rear down twice & front up once)
• At deceleration to stop -> 2, 1, 1 (rear down twice, front down once)

Practice shifting gears in a variety of situations.

The most important thing after understanding how to shift gears without chain slippage is to actually try shifting gears in a variety of situations.

Even if you know what you are doing in theory, when you actually get out on the road, you may start to panic, and depending on the traffic conditions, you may not be able to shift as you expect.

The only way to learn how to shift gears is to practice, so practice in a place where there is little traffic and learn by heart.