Bowling ball core · Roto Grip
Roto Grip Cage Core
Asymmetric Roto Grip core
An asymmetric core with mid-lane rev-up and high flare, built for heavy oil. Balls with this core are no longer available at BowlersMart.
- Asymmetric
- RG 2.520
- Diff 0.054
- MB 0.015
Specs
RG AT 15 LB
2.520
Mid-lane rev-up
62% of the reactive and urethane balls we stock have a lower RG.
DIFFERENTIAL AT 15 LB
0.054
High flare
83% of the reactive and urethane balls we stock have a lower differential.
MASS BIAS AT 15 LB
0.015
Mild asymmetry
22% of the asymmetric reactive and urethane balls we stock have a lower mass bias.
| Weight | RG | DifferentialDiff | Mass biasMB |
|---|---|---|---|
| 16 lb | 2.520 | 0.053 | 0.015 |
| 15 lbUsed on this page | 2.520 | 0.054 | 0.015 |
| 14 lb | 2.530 | 0.054 | 0.015 |
| 13 lb | 2.570 | 0.032 | 0.015 |
| 12 lb | 2.590 | 0.029 | 0.015 |
Source: Roto Grip published specs, as shown on BowlersMart’s original Roto Grip Cage core page (2022). RG and differential change with ball weight; use the row for the weight you throw. The highlighted 15 lb row is the one used on this page.
Looking for a ball like your Roto Grip Cage?
Balls with the Roto Grip Cage Core are no longer available at BowlersMart. These in-stock balls have the closest RG and differential.

Motiv Propulsion MXV Pearl Reactive
Heavy oil

Hammer HK22 C2 Solid Reactive
Medium to heavy oil

Roto Grip RST Hyperdrive Pearl
Roto Grip U-R1 Pearl Reactive
Medium to heavy oil

Hammer HK22 C2 Solid Reactive
Medium to heavy oil

Brunswick Infinity Quest Pearl
Brunswick EVO Pearl HK22C Reactive
Medium to heavy oil

Storm ReX Pearl Reactive
Medium to heavy oil
Balls with the Roto Grip Cage Core
None of the 2 balls with the Roto Grip Cage Core are in stock at BowlersMart right now.
Show 2 balls no longer available at BowlersMart
| Ball | Cover | First seen |
|---|---|---|
| Roto Grip Sinister Bowling Ball | Roto Grip 76H Hybrid Reactive | June 2014 |
| Roto Grip Menace Bowling Ball | Roto Grip 74H Solid Reactive | June 2015 |
Where the Roto Grip Cage sits
Each dot is a core in balls we stock. Cores close together roll alike; the cover and layout decide the rest.
Navy ring = a ball in your bag. Dashed ring = off this chart, or this same core.
Nearest cores, zoomed in
Navy ring = a ball in your bag. Dashed ring = off this chart, or this same core.
This core 1 Nearest cores Other cores
| Core | Brand | Shape | RG | Diff | vs this core |
|---|---|---|---|---|---|
|
|
Motiv | Asymmetric | 2.520 | 0.055 | RG 0.000 · Diff +0.001 |
|
|
Roto Grip | Asymmetric | 2.520 | 0.055 | RG 0.000 · Diff +0.001 |
|
|
Hammer | Asymmetric | 2.524 | 0.053 | RG +0.004 · Diff −0.001 |
|
|
Hammer | Symmetric | 2.520 | 0.052 | RG 0.000 · Diff −0.002 |
|
|
Brunswick | Asymmetric | 2.521 | 0.051 | RG +0.001 · Diff −0.003 |
|
|
Columbia 300 | Asymmetric | 2.510 | 0.053 | RG −0.010 · Diff −0.001 |
Matches use 15 lb RG and differential.
Drilling and tools
When needing midlane motion the Cage Core is exactly what the doctor ordered. With its top and bottom caps sandwiched around the ribs of the core body, this core creates motion like nothing else on the market. The Cage Core, first featured on the Sinister features medium-RG/High Differential/High MB Differential that reads the mid-lane and reacts with a phenomenal motion on the back end. Heads will roll with this kind of motion, making it perfect for the heaviest of oil patterns.
Questions bowlers ask
What is the RG of the Roto Grip Cage Core?
At 15 lb the Roto Grip Cage Core has an RG of 2.520. It ranges from 2.520 to 2.590 across the listed weights.
What is the 14 lb RG of the Roto Grip Cage Core?
At 14 lb the RG is 2.530.
What is the differential of the Roto Grip Cage Core?
At 15 lb the differential is 0.054. The mass bias is 0.015.
Which bowling balls use the Roto Grip Cage Core?
Roto Grip Sinister Bowling Ball, Roto Grip Menace Bowling Ball. 0 are in stock now.
Can I still buy a ball with the Roto Grip Cage Core?
Balls with this core are currently unavailable at BowlersMart. Closest in-stock alternatives by RG and differential include Motiv Apex Jackal Bowling Ball, Hammer Zero Mercy Solid Bowling Ball, Roto Grip RST Hyperdrive Pearl Bowling Ball, Hammer Fallout Bowling Ball, Brunswick Infinity Quest Pearl Bowling Ball, Storm Identity Bowling Ball.
How do the Roto Grip Cage Core specs change by weight?
At 16 lb: RG 2.520, differential 0.053, mass bias 0.015. At 12 lb: RG 2.590, differential 0.029, mass bias 0.015.
How does the Roto Grip Cage Core compare with my ball?
Type the ball you throw into the Compare with your ball box on this page. It shows the RG and differential side by side and saves your bag for every core page.
Sources and method
Specs. Roto Grip published specs, as shown on BowlersMart’s original Roto Grip Cage core page (2022), as published by the manufacturer.
Baseline. The baseline is 265 in-stock, published reactive and urethane balls. Plastic and polyester covers, 2-piece, 3-piece and pancake cores, missing covers and missing RG or differential values are excluded.
Percentiles. Percentiles are the share of baseline balls with a strictly lower or higher value; ties are not counted.
Nearest cores. Nearest cores are ranked by distance on standardized 15 lb RG and differential, with the same symmetric or asymmetric shape preferred among near ties (distance bands of 0.1).
Mass bias. Mass bias is compared among asymmetric balls with numeric mass bias only.
Updated. Catalog and page updated 2026-10-16.


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