IsoSpeed Black Fire 17 vs Kirschbaum Helix 17

Measured, side by side

Bars are percentile against all 791 strings, and the marked side is the one that measures better, which is not always the one you want. A firmer bed is worse for your elbow and better for your control, and no measurement knows which of those you came for.

Which one wins, by problem

Each string's standing on the site's rankings, out of every measured string in the database. This is where a comparison stops being arithmetic and starts being a decision.

• More spin and shape

  Black Fire 17258th

  Helix 17261st

• Easier on my arm

  Black Fire 17575th

  Helix 17661st

• More control, less launch

  Black Fire 17205th

  Helix 17135th

• More power and depth

  Black Fire 17556th

  Helix 17650th

• Plays the same for longer

  Black Fire 17520th

  Helix 17581st

• Lasts longer before it breaks

  Black Fire 17160th

  Helix 17210th

• Best feel and touch

  Black Fire 17558th

  Helix 17655th

Swapping between them: what tension?

Bed stiffness is published at one reference tension, so the only honest conversion is to scale it. These are starting points from 52 lb, not prescriptions. The calculator takes your own tension.

Hybrid: what if you used both?

Estimated, not measured. No hybrid combination has been tested as a bed. These figures are the two strings' own lab measurements weighted by how much of the bed each one actually is. Treat them as a guide to which way a pairing moves, never as lab data.

Open this in the hybrid builder

Which goes dead first?

Estimated from tension loss, which is the only thing the database measures about ageing. This is when the bed stops playing the way you strung it, not when the string breaks.

Both strings in full

Add a third string Black Fire 17 in full Helix 17 in full