Hammerhead
Hammerhead Karoo 3
$524.99
Released 2024-05
Best Bike Computers · head-to-head
Hammerhead Karoo 3 vs Sigma ROX 12.1 Evo
A sourced, side-by-side comparison. Sigma ROX 12.1 Evo is cheaper at $379.95. Every spec and price links to its source.
Sigma
Sigma ROX 12.1 Evo
$379.95Cheaper
Released 2023-06
Which is better: the Hammerhead Karoo 3 or Sigma ROX 12.1 Evo?
The Sigma ROX 12.1 Evo wins 1 of the 1 specs we compare head to head; the other wins 0. The Sigma ROX 12.1 Evo is the cheaper at $379.95. The Sigma ROX 12.1 Evo both leads on specs and costs less — the straightforward pick.
As an Amazon Associate we earn from qualifying purchases. Prices verified at capture; live price may differ.
Full spec sheet
✓ marks the stronger figure where "more" — or "less", for price and weight — is unambiguously better.
| Spec | Hammerhead Karoo 3 | Sigma ROX 12.1 Evo |
|---|---|---|
| US price | $524.99 | $379.95 MSRP, basic set (device + mount) |
| Brand | Hammerhead | Sigma |
| Released | 2024-05 | 2023-06 |
| Display size (in) | 3.2 in | 3.0 in |
| Touchscreen | Yes | Yes |
| Battery life hours | 15 | 14 |
| Preloaded maps | Yes | Yes |
| Multiband gnss | Yes | No |
| Connectivity | ANT+, Bluetooth, Wi-Fi | ANT+, Bluetooth, Wi-Fi |
| Weight (g) | 118 | 112 |
| Release | 2024-05 | 2023-06 |
Sources — Hammerhead Karoo 3: shop.sram.com (verified 2026-06-19). Sigma ROX 12.1 Evo: sigma.bike (verified 2026-06-19).
What's the difference between the Hammerhead Karoo 3 and Sigma ROX 12.1 Evo?
Where the two actually differ on the specs we track (4 of 7). Matching specs are omitted.
- Display size (in): Hammerhead Karoo 3 3.2 in vs Sigma ROX 12.1 Evo 3.0 in
- Battery life hours: Hammerhead Karoo 3 15 vs Sigma ROX 12.1 Evo 14
- Multiband gnss: Hammerhead Karoo 3 true vs Sigma ROX 12.1 Evo false
- Weight (g): Hammerhead Karoo 3 118 vs Sigma ROX 12.1 Evo 112
What reviewers say
Sourced tester consensus for each — the "what people who used it think" layer, not just specs.
Hammerhead Karoo 3
Both whitelisted testers reviewed the Karoo 3. DC Rainmaker ran multi-month, side-by-side testing against the Garmin Edge 840 and Wahoo ROAM V2 (GPS/elevation data plots, battery-burn charts). Cycling Weekly did a hands-on but qualitative test on a Morocco ride, with no measured metrics. Both praise navigation and user-friendliness and call it a legitimate Garmin/Wahoo rival. Both note it is not meaningfully faster / slow to power up despite the new processor and RAM. On battery they diverge: Cycling Weekly found the 15+hr claim falls short in real use, while DC Rainmaker found the claimed ~30% improvement roughly holds (about 12-13hr realistic). No RTINGS or lab-benchmark source exists for this model. (2 sourced reviews, 2 lab-tested.)
Praised: Class-leading mapping and navigation (best-in-class per CW; top-2 and a core strength per DCR); Superior high-resolution 3.2-inch display; Standout user-friendliness and setup.
Flagged: Not meaningfully faster / slow to power up despite the new processor and RAM; Battery life is the weak point vs Garmin/Wahoo (15+hr claim fell short in real use); Weak structured-workout player / interface needs improvement.
Sigma ROX 12.1 Evo
Only one whitelisted tester (BikeRadar) published a hands-on review of this exact model. BikeRadar rated it 2/5, praising easy route-following and rich training data but panning meagre battery life (10h with a heart rate monitor only; 4.5h navigating with sensors), a rain-triggered touchscreen, cheap build and an uncompetitive £379.95 price. (1 sourced review, 1 lab-tested.)
Praised: Easy-to-follow turn-by-turn navigation and clear routing; Data-rich training metrics with a capable companion app.
Flagged: Meagre battery life, far below the claimed 14 hours; Touchscreen misbehaves in rain, skipping pages and changing settings; Uncompetitive £379.95 price versus Garmin/Wahoo rivals.