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You’ve Got Two Kettlebells in Your Cart — Now What?
Your garage gym is dialed in. Barbell, rack, maybe a set of dumbbells. But every time you want to throw in some swings, Turkish get-ups, or a quick conditioning finisher, you realize you’d need five separate kettlebells to cover your working weights. That’s a lot of cast iron eating up floor space you don’t have. So you’ve narrowed it down to an adjustable kettlebell set — specifically, the BowFlex SelectTech 840 and the Polyfit. Both promise to replace a whole rack. But they take very different approaches, and the wrong pick will collect dust faster than a shake weight.
Quick Answer
If you want the smoothest, most compact adjustable kettlebell experience, the BowFlex SelectTech 840 is our top pick. Its dial-based adjustment system lets you swap weight in seconds without interrupting your flow. If you’re training on a tighter budget and need heavier max loads, the Polyfit Adjustable Kettlebell Set delivers up to 50 lbs at a fraction of the cost. Both are solid — but they suit different lifters.
TL;DR
The BowFlex 840 wins on design, ease of use, and compactness. The Polyfit wins on value and top-end weight. Choose BowFlex for seamless transitions during circuits; choose Polyfit if you need heavier loads without breaking the bank.
Key Takeaways
- The BowFlex 840 adjusts from 8–40 lbs with a turn dial — no plates to fumble with mid-workout.
- The Polyfit offers 30, 40, or 50 lb configurations using a plate-loading system, giving you a higher ceiling.
- BowFlex is more compact and lives on a single base cradle; Polyfit requires you to manage loose plates.
- Polyfit costs significantly less, making it the budget-friendly choice for heavier kettlebell work.
- Neither replaces a competition kettlebell for serious sport-specific training, but both are excellent for general home gym conditioning.
Overview: What Is an Adjustable Kettlebell?
An adjustable kettlebell lets you change the weight of a single bell instead of buying multiple fixed kettlebells. Most models use either a dial mechanism, a pin-and-plate system, or removable weight plates to shift between increments.
For home gym owners, the appeal is obvious: one kettlebell replaces four, five, or six individual bells. That saves hundreds of dollars and a serious chunk of floor space. You get the versatility to go light for halos and windmills, then heavy for swings and goblet squats — all without a kettlebell graveyard in the corner.
The trade-off? Adjustable kettlebells are generally bulkier than their fixed counterparts, and the adjustment mechanism adds a layer of complexity. The question is whether that trade-off is worth it — and which design handles it better.
Head-to-Head Comparison Table
| Feature | BowFlex SelectTech 840 | Polyfit Adjustable Kettlebell |
|---|---|---|
| Weight Range | 8–40 lbs | 30/40/50 lbs |
| Weight Increments | 6 settings (8, 12, 20, 25, 35, 40 lbs) | 3 settings (30, 40, 50 lbs) |
| Adjustment System | Turn-dial selector | Plate-loading |
| Max Weight | 40 lbs | 50 lbs |
| Footprint | Compact (sits in cradle) | Moderate (loose plates) |
| Handle Feel | Ergonomic, molded | Standard cast handle |
| Ideal For | Circuits, flows, lighter work | Heavy swings, strength work |
| Adjustment Speed | ~3 seconds | 15–30 seconds |
| Drop-Safe? | No — not designed to be dropped | More tolerant of drops |
| Price Range | Higher | Budget-friendly |
BowFlex SelectTech 840 — Full Breakdown
The BowFlex SelectTech 840 Adjustable Kettlebell is built for the lifter who wants fast weight changes and a clean setup. You turn the dial, lift the bell out of its cradle, and you’re working. Six weight settings from 8 to 40 lbs cover everything from rehab-level halos to moderately heavy swings.
The ergonomic handle is comfortable during high-rep sets, and the compact cradle means it takes up about as much space as a shoe box. It’s ideal for circuit-style training, kettlebell flows, and conditioning finishers where you don’t want to stop and fiddle with plates.
The honest limitations: 40 lbs is the ceiling, which experienced lifters will outgrow on two-handed swings quickly. The internal mechanism means you absolutely cannot drop this bell — one hard slam and you risk cracking the housing. And the non-standard shape takes some getting used to if you’ve only swung traditional cast iron.
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Polyfit Adjustable Kettlebell Set — Full Breakdown
The Polyfit Adjustable Kettlebell Set takes the straightforward approach: a solid kettlebell shell with removable weight plates that let you configure 30, 40, or 50 lbs. It’s a simple, no-nonsense design that prioritizes function and value.
At 50 lbs max, it gives stronger lifters room to actually load heavy swings, cleans, and goblet squats — something the BowFlex can’t match. The plate-loading system is more durable by nature since there’s no delicate dial mechanism to protect. You can train a bit more aggressively without babying the equipment.
The trade-offs: changing weight means unscrewing and swapping plates, which takes 15–30 seconds and interrupts flow workouts. You’ve also got loose plates to store. And with only three weight settings, the jumps between loads are significant — there’s no light option for Turkish get-ups or single-arm presses if you’re still building strength.
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Category-by-Category Verdict
Ease of Use
BowFlex wins here, and it’s not close. Turn a dial, lift, and go. The Polyfit’s plate-swap system works fine, but it kills momentum during supersets and circuits. If you’re doing timed intervals, that 20-second plate change adds up fast.
Winner: BowFlex SelectTech 840
Weight Range & Versatility
The Polyfit takes this one. Its 50-lb max gives you 10 more pounds to work with at the top end, and that matters for two-handed swings, heavy goblet squats, and loaded carries. The BowFlex’s lower increments (8 and 12 lbs) are nice for warm-ups and lighter movements, but most lifters will crave more top-end load over time.
Winner: Polyfit
Build Quality & Durability
Both are well-constructed, but the Polyfit’s simpler plate-loading design has fewer parts that can break. The BowFlex’s internal dial mechanism is a potential failure point, especially if you accidentally drop it. For a garage gym that sees rough use, the Polyfit is the safer long-term bet.
Winner: Polyfit
Space Efficiency
The BowFlex sits neatly in its cradle and takes up minimal floor space — roughly one square foot. The Polyfit itself isn’t huge, but you’ve got extra plates to stash somewhere. If your home gym is a corner of a bedroom or a tight apartment space, the BowFlex’s tidiness matters.
Winner: BowFlex SelectTech 840
Value for Money
The Polyfit delivers more total weight for less money. If your main concern is getting the heaviest possible kettlebell training without spending a premium, this is the clear choice. The BowFlex commands a higher price for its convenience features.
Winner: Polyfit
Who Should Buy Which?
Buy the BowFlex SelectTech 840 if you:
- Train with kettlebell circuits, flows, or HIIT-style conditioning
- Need quick weight changes during supersets
- Value a compact, tidy setup in a small space
- Work primarily in the 8–40 lb range for kettlebell-specific movements
- Treat your equipment carefully (no drops)
Buy the Polyfit Adjustable Kettlebell Set if you:
- Need heavier loads (40–50 lbs) for swings, cleans, and squats
- Want the best bang for your buck
- Prefer a simpler, more durable design with fewer breakable parts
- Don’t mind spending 20–30 seconds between weight changes
- Train in a garage or dedicated gym space with room for extra plates
FAQs
Can you do Turkish get-ups with the BowFlex 840?
Yes. The 8-lb and 12-lb settings work well for get-ups. The shape is slightly wider than a traditional bell, so practice the overhead lockout position before loading heavier.
Is the Polyfit kettlebell safe for one-handed swings at 50 lbs?
It can handle one-handed swings, but make sure the plates are securely fastened before every set. Check the locking mechanism periodically — loose plates mid-swing are a safety hazard.
Will the BowFlex break if I drop it?
Likely, yes. The internal dial mechanism isn’t designed for impact. Always set it down — never release it from overhead or let it slam. This is its biggest drawback for aggressive training styles.
Can I use either kettlebell for kettlebell sport training?
Neither is ideal for competitive kettlebell sport. Both have non-standard shapes and handle profiles. For sport-specific training, you’ll want a fixed competition kettlebell with a 33mm handle.
How loud are these during workouts?
The BowFlex is quiet since the weights lock internally. The Polyfit can produce some plate rattle if the fit isn’t perfectly snug. A thin rubber washer between plates helps eliminate noise.
Do I need a mat under either kettlebell?
A horse stall mat or thick rubber tile is smart for both. It protects your floor from accidental drops and reduces vibration during heavy swings. According to the American Council on Exercise, proper flooring also helps maintain joint-friendly footing during dynamic movements.
Which one is better for beginners?
The BowFlex, thanks to its lighter starting weight (8 lbs) and easy adjustments. Beginners can focus on form without wrestling with plates. The Polyfit’s lightest setting (30 lbs) is too heavy for most people learning basic kettlebell patterns.
Final Verdict
Both the BowFlex SelectTech 840 and the Polyfit earn their spot in a home gym — they just serve different lifters. If your training revolves around kettlebell flows, quick conditioning circuits, and you value a sleek, space-saving design, the BowFlex SelectTech 840 is the smarter buy. It’s the adjustable kettlebell set that stays out of your way and lets you focus on the work.
But if you’ve outgrown the 40-lb range, want a tougher build, and care more about value than convenience, the Polyfit Adjustable Kettlebell Set is hard to beat. It’s a workhorse that rewards strength-focused lifters without punishing their wallets.
Our overall pick? The BowFlex 840 — for most home gym owners, the speed and simplicity of the dial system makes every workout better. Grab the one that fits your training style, and start swinging.
Research from the National Strength and Conditioning Association (NSCA) confirms that kettlebell training improves both cardiovascular endurance and functional strength, making either of these a high-value addition to any home setup.
