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Kirschbaum

Black Shark 17 (1.25)

Polyester Gauge 17 1.25 mm In production

Lab measurements for Kirschbaum Black Shark 17 (1.25), ranked against all 789 strings in the database. Every figure below is a testing-machine result at a fixed reference tension, not a playtest opinion.

Measured values

Stiffness

217lb/in

lower = softer, kinder on the arm

Tension loss

38%

lower = stays where you strung it

Energy return

88%

higher = livelier, more free power

Spin potential

5.8

higher = more spin off the string bed

Ball bite

0.421COF

higher = grabs the ball harder

Snapback

0.072COF

lower = strings slide and snap back

How it ranks against all 789 strings

Stiffness 217 lb/in · 85th pct

Stiffer than 85% of strings tested.

Tension loss 38 % · 65th pct

Sheds more tension than 65% of strings tested.

Energy return 88 % · 48th pct

Livelier than 48% of strings tested.

Spin potential 5.8 · 76th pct

More spin potential than 76% of strings tested.

Ball bite 0.421 COF · 38th pct

Grips the ball harder than 38% of strings tested.

Snapback 0.072 COF · 7th pct

More string-on-string friction than 7% of strings tested — slides and snaps back freely.

Strings that play like this

Closest matches across stiffness, tension loss, energy return and spin potential.

Tecnifibre Ice Code 16 (1.30) 95% match Prince Tour XC 17L 94% match Prince Tour XC 16L 93% match Gamma IO Soft 15L (1.40) 93% match Luxilon ALU Power Rough 16L (1.25) 93% match Luxilon Element 16L (1.25) 93% match

More from Kirschbaum

What these numbers mean

Stiffness · lb/in

How much the string bed resists deflection. Higher plays firmer and more controlled; lower plays softer and easier on the arm.

Tension loss · %

Share of the reference tension the string sheds under a fixed test protocol. Lower means the bed stays where you strung it for longer.

Energy return · %

Share of impact energy handed back to the ball. Higher plays livelier and more powerful.

Spin potential

Ball friction divided by string-on-string friction. Higher means better bite with a cleaner snapback, so more spin.

Ball bite · COF

String-on-ball friction. Higher grabs the ball harder through the brush.

Snapback · COF

String-on-string friction. Lower lets the mains slide and snap back into place after impact.

Compare Black Shark 17 (1.25) against 789 strings Find the right string for me