# Stringinging techniques: 4 knots with progressive tension

In this case, we analyzed what happens when you string a racquet with a progressive tension pattern.
In this case, progressively lower tensions were adopted because of the shorter length of the string, both for vertical and horizontal ropes.

The reference tension for the power plants is once again 24kg.

### What do we expect from this kind of stringing?

We consider that this stringing technique, which has its roots in experiments conducted in the 70s and 80s and beyond up to the present day, has among its objectives the maximisation of comfort and the maximum extension of the useful impact area in favour of playability.

The theory behind the progressive stringing is that the deflection stiffness of a string depends inversely proportional to its length.

```Klateral = 4 x tension / length (kg/mm)

Klateral = 4 x 24.0 / 320 = 0.3 (kg/mm) - Klateral = 4 x 22.5 / 300 = 0.3 (kg/mm)

Klateral = 4 x 18.0 / 240 = 0.3 (kg/mm) - Klateral = 4 x 15.0 / 200 = 0.3 (kg/mm)```

By adopting a differentiated pattern of tensions based on the length of the strings, it is therefore possible to expect maximum uniformity in terms of flexural rigidity of the strings installed on the plate and a significant enlargement of the useful impact area.

This type of stringing must be carried out by highly specialised personnel who are familiar with advanced stringing techniques, using machines with 6 fixing points and a constant pull system.

The time needed to string a frame with the “progressive stringing” technique is longer than that used for a “standard” type stringing, since the tension must be changed string by string.

A small note regarding the possibility of customising the scheme, which does not provide for a single mode of differentiation but which can be made unique on the basis of the “art” and expertise of the stringer.

 Advantages Disadvantages greater power ⇨ greater output angle optimum performance on topspin shots ⇨ less friction between strings ⇨ maximum snap-back increased comfort greater tolerance in the game phase less stress and deformation for the frame less control homogenisation of the tensions after a few hours of play shorter dynamic duration when used with high level players complexity of implementation of the stringing scheme

### Sweetspot analysis

 Racket used Babolat Pure Drive 2018 String used Signum Pro Poly Plasma 1.23 Schema 4 knots with progressive tension Tension mains 24-24-24-23.5-23-22.5-22-22 kg (starting from the center symmetrically outwards) Tension crosses 21.5-21.5-22-22.5-23-23.5-24-24-24-24-24-24-23.5-23-22.5-22-22-21.5 kg (from the head down to the throat) Knot overtension +10%
 Real tension of the stringbed detected with pro-t-one chromatic S.T.D. 22 kg Vibration frequency 588Hz Waiting time 4 hours Real tension of the stringbed detected with pro-t-one chromatic S.T.D. 21.6kg ⇨ loss of tension -0.4kg Vibration frequency 577Hz Rated dynamic stiffness of the top of the platter 37 DT-CH ⇨ the middle part of the plate: 33.3 DT-CH

The first element that must be highlighted is the effective homogeneous tension detected of 22kg, which corresponds to -2kg compared to the nominal tension due to the scalar tensions adopted from the centre towards the external areas of the frame.
The feeling of comfort and softness will be characteristic of this type of stringing.

From what emerges from the test it is possible to notice an excellent tensional uniformity in terms of rigidity of the stringbed.
The useful impact area is optimal in the lateral area as well as in the lower area of the stringbed and in the upper part the increase in stiffness is limited to a value equal to 17% to guarantee greater softness in the impact phase and greater comfort.