String Project Sirius

Written by: Jonas Eriksson | March 17, 2024

I have several new strings to test. Except for the hyped-up Restring Sync, I will also test String Project Sirius.

What is String Project?

String Project is an Italian brand. Their focus is on arm-friendly strings. We have favorably reviewed some of their strings like Gold and Magic before. Sirius is a round, green control-focused string with “arm-friendly” technology.

What is different and nice about String Project strings is that they always publish data on their strings from lab tests and you can download pdfs on their website on the different strings.

Technologies of String Project strings

Pre-stretch
The idea of pre-stretching the string is to minimize tension loss.

Multiple heating
This process is to make the strings more flexible and elastic.

Liquid Wax
The wax layer is supposed to make the string more durable and makes it easier to string.

Low friction
The idea with low friction is to improve snapback of the string.

Spring load
This is another technology to increase tension maintenance.

Sirius String Characteristics

First impressions

This was a very enjoyable string to string. The wax coating and round profile help the string move easily through fingers and grommets.

My first hit was in a Wilson Blade 98 V8 18/20. The string felt soft to me (like most String Project strings) and I wanted to maintain control, so I went for 53 lbs or 24 kg.

I immediately noticed a nice sensation during warm-up. The string is soft and comfortable despite a medium-high tension in an 18/20 string bed. The sound when striking the ball had a nice “thwack” to it and the string seems to offer decent snapback. It is not going to grab the ball like a shaped string, but compared to other round strings it performed well.

I am curious to see how it plays in a more open string pattern racquet.

More to come about String Project Sirius. You can check out their official website. You get 5% off your string purchase using the code TENNISNERD5.

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Jonas Eriksson

Jonas has been known as "tennis nerd" mainly for his obsessing about racquets and gear. Plays this beautiful sport almost every day.