Dead Spot Score Explained (part 2)

Hello, I’m Fukuma from LEOMO. In the previous article, I shared the concept behind DSS (Dead Spot Score), a metric that measures the smoothness of your pedaling motion using LEOMO’s TYPE-R portable motion analysis device.

If you haven’t read it yet, please check it out. After reading the previous article, you will have a better understanding of what we’re discussing today; the movement of the actual pedaling motion that contains a dead spot, compared to one without any dead spots.

What sort of movement causes dead spots?

Previously, I highlighted the key difference in a cyclists’ pedaling movement: the smoothness of acceleration and speed of the foot as it pedals. What does this look like in terms of movement?

First, let’s review the graph of the foot angular speed showing dead spots, introduced in the previous article:

LEOMO DSS Part 2

As you can see, there is a “dent” on the top of the curve, this shows that the rate of acceleration has a wobble, which means that the pedaling motion of the foot isn’t smooth. That’s a dead spot. This dead spot is located where the foot reaches the fastest rotational speed at 150 degrees/sec, occurring around the 6 o’clock position.

In this video you can see the pedaling motion with dead spots occurring at the 6 o’clock position:

As with general heel-up / heel-down pedaling movements, the heel-up motion starts around 4 o’clock. The heel stays up as it passes through the 6 o’clock position, and continues all the way to the 10 o’clock position. After that, the heel starts to move down as the foot moves towards the 3 o’clock position.

The difference between smooth and non-smooth pedaling motions in this example lies specifically in the movement right before the 6 o’clock position. In this example, the cyclist is performing a smooth pumping motion with their feet, yet between the 5 and 6 o’clock position, they start to “stretch” their toes downwards. This causes the heel to move up more than what’s natural since the motion is in addition to the heel-up motion that’s already occurring. The heel then moves higher than what is natural (sometimes high enough it can’t move it any higher mechanically), causing the movement of the foot to lock momentarily as the foot slides over the 6 o’clock position. The heel then shifts to a heel-down movement at 10 o’clock. This sort of non-smooth motion causes dead spots, raising the overall Dead Spot Score.

In comparison, this video shows a smooth pedaling motion with no dead spots. 

Can you spot the differences between the two videos? Remember that in the example we just went over, the 6 o’clock position is where the dead spots are occurring. The differences are very subtle and are pretty tough to catch by eye, but some can see that the overall movement is not smooth, though they have a hard time pinpointing where that non-smooth motion is occurring exactly. The TYPE-R can help out with that.

Question time!

The two videos above show pedaling motions with and without dead spots. We pointed out the non-smooth pedaling motion that occurs at the 6 o’clock position. However, there are actually other positions that have dead spots. Can you find them?

In part 3, we will share the correct answer. Read Dead Spot Score Explained, Part 3.

For more information on the TYPE-R portable motion analysis lab, please visit leomo.io.


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