Measured values

Stiffness

167lb/in

lower = softer, kinder on the arm

Tension loss

62%

lower = stays where you strung it

Energy return

79%

higher = livelier, more free power

Spin potential

4.0

higher = more spin off the string bed

Ball bite

0.362COF

higher = grabs the ball harder

String friction

0.090COF

lower = strings slide and snap back

How it ranks against all 791 strings

Stiffness 167 lb/in · 35th pct

Stiffer than 35% of strings tested.

Tension loss 62 % · 98th pct

Sheds more tension than 98% of strings tested — goes dead fast, expect frequent restringing.

Energy return 79 % · 1st pct

Livelier than 1% of strings tested — very muted and low-powered.

Spin potential 4.0 · 30th pct

More spin potential than 30% of strings tested.

Ball bite 0.362 COF · 5th pct

Grips the ball harder than 5% of strings tested — slick against the ball.

String friction 0.090 COF · 46th pct

More string-on-string friction than 46% of strings tested.

Like Classic 17 (1.20), but…

Almost nobody looks a string up out of curiosity. You are here because something about your current setup is wrong. Each list below keeps the rest of this string's profile as close as it can while moving decisively on the one thing you picked, so these are swaps rather than merely different strings.

SofterKinder on the arm

FirmerMore control, less launch

More spinBites and snaps back harder

More powerHands more back to the ball

Holds tensionStays where you strung it

What Classic 17 (1.20) is actually good for

Its standing on each of the site's rankings, out of every measured string in the database. Same arithmetic as the finder, not a separate opinion.

How long it lasts, and how far it stretches

Playable life

~11hours

Estimated from tension loss, on a scale running from 40 hours for the best-holding strings in the database down to 10 for the worst. At four hours a week that is about 3 weeks.

Estimated, not measured. This estimates when the bed goes dead, not when the string snaps. If you break strings before you notice them going dull, you are a breaker, and thickness and material matter far more to you than tension hold does.

Track this in a setup

Elongation under load

This stringDatabase median

How far the string stretches when tensioned to a given load. A string that elongates more absorbs more of the impact itself and feels softer; one that barely moves passes more of it on to the frame and the arm.

Measured at every tension and swing speed

The figures at the top of this page come from one test condition: 51 lb at fast swing speed. There are nine in total, and all of them are below. Tension moves the bed more than the choice between two similar strings does, so this is the table that actually answers "what will it feel like for me".

Bed stiffness against tension · Fast swing

Measured at 3 tensionsFitted response

Measured at three tensions, with the fitted response drawn across the whole stringable range. The line does not pass through the origin: this bed carries about 5 lb/in that does not come from tension at all, and gains roughly 3.3 lb/in for every extra pound you string it at.

Convert a tension with this

What that means

Stringing Classic 17 (1.20) at 30 lb gives a bed of about 103 lb/in; at 70 lb it is about 234 lb/in. That range is wider than the gap between most pairs of strings on this site, which is the single most useful thing this page can tell you.

Stiffness lb/in lower = softer, kinder on the arm

Strung at	Slow swing	Medium swing	Fast swing
40 lb 18.1 kg	189	159	138
51 lb 23.1 kg	220	189	167
62 lb 28.1 kg	261	232	210

Tension loss % lower = stays where you strung it

Strung at	Slow swing	Medium swing	Fast swing
40 lb 18.1 kg	65	65	65
51 lb 23.1 kg	61	62	62
62 lb 28.1 kg	52	52	52

Energy return % higher = livelier, more free power

Strung at	Slow swing	Medium swing	Fast swing
40 lb 18.1 kg	87	80	74
51 lb 23.1 kg	90	84	79
62 lb 28.1 kg	94	90	85

The highlighted cell is the condition every other figure on this site is quoted at.

What else the machine recorded

Further measurements from the same test, given at the reference condition of 51 lb, fast swing.

Dwell time

38.9ms

How long the ball stays on the string bed. Longer dwell is the physical basis of what players call hold or pocketing.

Bed deflection

34.5mm

How far the string bed moves at impact. More deflection means the bed is doing more of the work of stopping the ball.

Peak force

30lb

The highest force perpendicular to the string bed during impact. The spike the frame and the arm actually receive.

Tension at impact

19.9lb

What the bed is actually pulled to by the time the ball arrives, after it has settled. Always lower than the tension it was strung at.

Loss: settling

10.3lb

Tension lost simply from being strung and left alone, before a ball is hit.

Loss: bedding in

20.5lb

Tension lost while the bed settles over its first impacts.

Loss: impact

0.4lb

Tension lost to the impact itself. Frequently negative, because a bed often gains tension across an impact rather than losing it.

Loss: total

31.3lb

The three losses above added together, in pounds.

Strings that play like this

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

Poly Star Energy 17 (1.20) 99% match Polyfibre TCS 16L 97% match Poly Star Energy 16 (1.30) 97% match Polyfibre Poly Hightec 16/1.30 96% match Poly Star Energy 16L (1.25) 96% match Polyfibre Hightec Premium 16/1.30 95% match

Head to head: Classic 17 (1.20) vs Energy 17 (1.20) · Classic 17 (1.20) vs TCS 16L · Classic 17 (1.20) vs Energy 16 (1.30)

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.