Different bar widths - explained!



Today I’m going to talk about an interesting topic that continues to cause controversy - even amongst myself and colleagues at DUOTONE - the width of a kite bar.

As you may have noticed, there is no standardised bar width within the kite industry. So let’s explore why and try to find the right setup for you.


Does a narrow bar make your kite slower?


The biggest misconception is that a narrow bar automatically makes a kite turn slower.

If you look at the picture below, you’ll see the small (42cm) and the standard (49cm) DUOTONE Click Bar.


In order to conclude which is better for you, we first must understand the maths behind the different bar widths. As an example I have illustrated a typical steering scenario. Both bars are turned 45°. The difference in the back line length is 2.5cm. That means, the wider bar shortens the back lines 2.5cm compared to the shorter Bar, on a similar turing angle.

To achieve a similar reduction of the steering line length on the shorter 42cm bar, you have to pull the bar 10° more.


Why does the bar width have to vary?

Mainly there are two variables to look at:

  • The kite size.

  • The stall point.

If you scale a 10m² kite up to 15m² without changing any of its design parameters, you would automatically increase the steering length. This is easy to understand as the 15m² kite has a much wider tip area than the 10m² kite and therefore has to be bent more to reach the same level of deforming.

Does this mean the bigger the kite, the longer the bar has to be?


Not necessarily. For example, the EVO comes in 11 sizes and all of them have different aspect ratios and tip geometries that offset the steering input length. However, this change in parameters does have a certain limitation called the stall point.



Every kite reaches a stall point when you pull on the steering lines too much. This stall point sets the lower limit of the steering line length and forces the designer to either, increase the tip area or choose a smaller bar width. The overall steering line length between the 42cm and 49cm bar is 3.5cm. This sounds marginal but it makes a huge difference on a 4m² kite.


Does the width change the bar feedback?

The clear answer is yes. A wider bar on a small kite - like an 8m² - will give you an imprecise feeling under strong and turbulent conditions. This is due to the fact that there is always a certain movement between the rider and the kite, especially in rough sea conditions. This movement results into a shaking bar which will give you the feeling of being disconnected from the kite. It’s a bit like having power steering that’s too soft in your car. It’s not precise enough around the middle axis.


Conclusion.

Smaller kites do require smaller bars. At DUOTONE we have agreed on having two different bar widths that perfectly capture all sizes from 4m² to 17m². This works because we are changing and adapting the design parameters on every single kite and size.


I highly recommend the following rules for all kite models:

Use the small bar on kites 4m² to 10m². Use the wider bar on kites 11m² to 17m². Since the wider bar also comes with 2m longer lines than the small bar, the low-wind abilities are noticeably improved. In my eyes, a 49cm bar should not be flown with an 8m² kite as the steering input and precision is not on the same handling level as it would be on the 42cm version.

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