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We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-27 · 7 min read · Independent comparison
• HAKII Light 2 — biggest strength: an open-ear air-conduction design plus a 180° ultra-bright beacon string with three lighting modes, so you're both aware of traffic and visible to it. That's a rare combination in cycling audio.
• HAKII Light 2 — biggest trade-off: open-ear designs trade isolation for awareness, so wind noise and road rumble stay audible, and the 16-hour battery is solid but not extreme.
• Acjohtin Earbuds — biggest strength: up to 90 hours of total playback with the charging case, IPX7 waterproofing and over-ear hooks that hold a seal through sweat and rough surfaces.
• Acjohtin Earbuds — biggest trade-off: the in-ear seal and 45dB ENC noise reduction block out more of your surroundings, which is the opposite of what a road cyclist usually wants.
• Choose HAKII Light 2 if you ride on roads, at dawn or dusk, and want to hear cars while being seen by them.
• Choose Acjohtin Earbuds if your "cycling" is mostly indoor trainer sessions, long solo gravel grinds or multi-day rides where battery life is the whole game.
The HAKII Light 2 is built around a single idea: you should never be cut off from the world around you while you ride. That's the open-ear, air-conduction approach. Nothing goes into your ear canal, so traffic, bells, tyre noise and a riding partner's voice all come through naturally. HAKII's own framing contrasts this with bone conduction, which it argues needs heavy clamping force and vibrates against the tragus — the Light 2 sidesteps that by firing sound directionally toward your ear from outside it. Whether or not you buy the hearing-health argument, the practical benefit on a bike is real: situational awareness is a safety feature, not a compromise.
The second half of that safety story is the 180° ultra-bright beacon string. Three lighting modes make you visible to drivers approaching from behind and the sides, which matters far more on a bicycle than on a treadmill. Add IPX5 water resistance for sweat and rain splashes, Bluetooth 6.0 for a stable 10-metre connection with low latency, and dual AI noise-cancelling microphones for calls, and you have a headset designed for outdoor movement rather than a desk.
Buy it if you ride outdoors in mixed traffic, at dawn or dusk, or in low light; you want to hear your surroundings; or you dislike things sitting inside your ears for long periods. Skip it if you mostly train indoors and want heavy noise isolation, or you want a single charge to last a week of long sessions.
Acjohtin Earbuds: Who It's For
The Acjohtin Earbuds take the opposite philosophy: seal the ear, lock the fit, and outlast everything. The headline number is 90 hours of total playback with the charging case, plus 8 hours from a single charge. For a cyclist doing long rides, back-to-back training days or a multi-day trip, that changes how you pack — you're not hunting for a socket every evening. The LED digital display on the case shows battery levels for both the buds and the case, which is a small thing that saves you from a dead-bud surprise mid-ride.
Instead of an open design, Acjohtin uses flexible over-ear hooks with S/M/L interchangeable silicone tips, so the buds stay mechanically locked to your ear rather than relying on friction alone. On rough surfaces, that hook is what stops a bud from bouncing out. IPX7 waterproofing is a step beyond splash resistance — it handles sweat, rain and getting rinsed off afterwards without drama, which suits outdoor workouts and daily commuting alike.
Sound comes from 16.2mm dynamic drivers, slightly larger than the HAKII's 16mm, tuned for punchy bass and a balanced midrange — good for workout playlists and podcasts. Connectivity is Bluetooth 6.1 with a 33ft range and low latency, and Acjohtin claims it outperforms Bluetooth 5.4 in stability and data transmission. Four HD microphones with ENC noise reduction block up to 45dB of background noise for calls. Controls are touch-based rather than physical buttons, and the buds are compatible with mainstream phones, tablets, laptops and wearables. Warranty is two years.
Buy it if battery life and a secure in-ear seal top your list; you ride indoors or on quiet routes; or you want one pair for cycling, gym work, commuting and calls. Skip it if you ride in traffic and need to hear what's coming — that noise reduction is working against you there — or you simply prefer nothing inside your ear canal.
• Best for on-road safety and visibility → HAKII Light 2. The open-ear design plus the 180° beacon string is purpose-built for being seen and staying aware.
• Best for battery life → Acjohtin Earbuds. Up to 90 hours total with the case versus the HAKII's 16 hours per charge.
• Best for secure fit during hard efforts → Acjohtin Earbuds. Over-ear hooks plus three tip sizes physically lock the bud in place.
• Best for hearing traffic and ride partners → HAKII Light 2. Air conduction leaves your ear canal open, so ambient sound comes through.
• Best for rain and heavy sweat → Acjohtin Earbuds. IPX7 is a higher water-resistance rating than the HAKII's IPX5.
• Best for long, low-light outdoor rides → HAKII Light 2. The three-mode lighting is a genuine differentiator once the sun drops.
• Best for call clarity in noisy places → Acjohtin Earbuds. Four mics with ENC rated to block up to 45dB of background noise.
• Best for all-day comfort without ear pressure → HAKII Light 2. 26g with a flexible titanium frame and no in-ear insertion.
• Best for one pair across many activities → Acjohtin Earbuds. Wider use-case coverage from commuting to gym to travel.
For cycling specifically, I'd buy the HAKII Light 2. In my opinion, the deciding factor isn't sound or battery — it's that the open-ear design and the beacon string solve the two problems that actually matter on a bike: hearing traffic and being seen by it. The 16-hour battery, 26g frame and IPX5 rating are all adequate for real rides. I'd only steer you to the Acjohtin Earbuds if your riding is mostly indoors or on car-free routes, where its 90-hour battery and IPX7 sealing become the smarter buy. Check the current price on Amazon before deciding, since that can shift which one looks like the better deal.
The HAKII Light 2, clearly. Its open-ear air-conduction design keeps your ear canal clear so you hear cars, and the 180° beacon string makes you visible. The Acjohtin's in-ear seal and 45dB ENC noise reduction work against you in traffic.
The HAKII Light 2 gives 16 hours of playback per charge with a one-hour charge time. The Acjohtin Earbuds give 8 hours continuous from a single charge, up to 90 hours total with the charging case.
They carry an IPX7 rating, which covers sweat, splashes and light rain — a higher water-resistance level than the HAKII Light 2's IPX5. For cycling in the rain, the Acjohtin has the edge on paper.
Not necessarily worse, just different. The HAKII Light 2 uses 16mm drivers and the Acjohtin uses 16.2mm drivers, so both aim at strong bass. The real difference is isolation: the Acjohtin seals your ear for fuller low-end, while the HAKII deliberately lets outside sound in.
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