Hybrid builder
Two strings,one string bed.
The mains carry most of the load, take most of the deflection and are the only strings that snap back. A hybrid is not the average of its two strings, and which one you put in the mains changes the answer more than which two you picked. Pick both and see where the bed lands.
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.
RPM Blast 16 mains / Poly Speed Spin 1.28 crosses
Babolat RPM Blast 16 (Polyester) in the mains, Signum Pro Poly Speed Spin 1.28 (Polyester) in the crosses. Every figure below is estimated from the two strings' own lab measurements.
Where the bed lands
Percentile against all 788 measured strings, as if this bed were one of them.
The bed against its own two halves
A hybrid is only worth the extra work if it lands somewhere neither string reaches on its own. This is where you find out whether yours does.
| Measurement | RPM Blast 16 alone | This hybrid | Poly Speed Spin 1.28 alone |
|---|---|---|---|
| Stiffness lower = softer, kinder on the arm | 233 | 238 | 246 |
| Tension loss lower = stays where you strung it | 46 | 44 | 41 |
| Energy return higher = livelier, more free power | 85 | 85 | 85 |
| Spin potential higher = more spin off the string bed | 4.5 | 4.5 | 4.3 |
| Ball bite higher = grabs the ball harder | 0.406 | 0.417 | 0.480 |
| Snapback lower = strings slide and snap back | 0.090 | 0.096 | 0.112 |
What the crosses change
Against a full bed of RPM Blast 16. Moves are in percentile points, and "better" always means more of the good thing whichever way the raw number points.
- Snapback −10 pts 0.090 → 0.096 COF mains weighted 75%
- Ball bite +8 pts 0.406 → 0.417 COF mains weighted 85%
- Tension loss +5 pts 46 → 44 % mains weighted 65%
The other way round
Poly Speed Spin 1.28 in the mains and RPM Blast 16 in the crosses is a different bed, not the same one described differently. Worth a look before you commit.
How this is worked out
Each measurement is a weighted average of the two strings, with the mains carrying the larger share. The share is not the same for every metric: bed stiffness is close to 60/40 because the crosses genuinely soften the bed, but spin is nearer 80/20 because snapback is a mains phenomenon and the crosses barely participate in it.
These splits are the conventional stringer figures, not measurements. Nobody has put a hybrid bed on the machine and published the result, so this cannot be validated against anything. Treat it as a guide to which direction a pairing moves, and never as lab data. The full methodology →
Shareable link: https://stringspec.com/hybrid/?mains=babolat-rpm-blast-16&crosses=signum-pro-poly-speed-spin-1-28