The Common Misconception: "More Gears = Better Bike"
When most people see "21 speeds" on a bike spec sheet, they assume it's superior to a "9-speed" model. After all, more is better, right?
Not on an e-bike.
The number on the spec sheet ("21" or "9") simply counts the total possible gear combinations. What actually matters for how the bike rides is:
- The lowest gear ratio — how easy it is to climb steep hills
- The highest gear ratio — how fast you can pedal on flat ground
- The spacing between gears — how smooth shifting feels
- The mechanical reliability — how often things go wrong
When you compare a modern 1×9 system to a traditional 3×7 (21-speed) system on these four metrics, the 1×9 wins on most of them — especially when paired with an electric motor.
What "1×9" and "21-Speed" Actually Mean
Traditional 21-Speed (3×7)
- 3 chainrings at the front (typically 28-38-48T)
- 7 cogs at the rear cassette (typically 14-28T)
- Two derailleurs (front + rear)
- Two shifters (left hand for front, right hand for rear)
- 21 theoretical gear combinations (3 × 7 = 21)
Modern 1×9
- 1 chainring at the front (typically 38-42T)
- 9 cogs at the rear cassette (typically 11-32T or 13-32T)
- One derailleur (rear only)
- One shifter (right hand)
- 9 gear combinations
The KINDYMA TITAN X (K01) and AURORA S (K02), for example, use a 42T front chainring × 13–32T 9-speed cassette — a setup that has become the new standard for mid-range e-MTBs across Europe.
Doing the Math: Gear Ratios Compared
A gear ratio tells you how many times the rear wheel turns for each turn of the pedals. Lower ratios = easier pedaling on hills. Higher ratios = more speed on flats.
KINDYMA 1×9 (42T × 13–32T)
| Rear Cog | Gear Ratio | Use Case |
|---|---|---|
| 13T | 3.23 | High-speed cruising |
| 15T | 2.80 | Flat road pace |
| 17T | 2.47 | Slight incline |
| 19T | 2.21 | Gentle climb |
| 21T | 2.00 | Moderate climb |
| 24T | 1.75 | Steeper climb |
| 28T | 1.50 | Steep climb |
| 32T | 1.31 | Climbing gear |
Traditional 3×7 (28-38-48T × 14-28T)
A typical 21-speed bike offers ratios ranging from about 1.00 (28T × 28T, the easiest climbing gear) to 3.43 (48T × 14T, the fastest gear).
What This Means in Practice
The 3×7 system has a slightly easier lowest gear (1.00 vs. 1.31). On a muscle-powered bike, that difference would matter on a 20% grade.
On an e-bike with 500W of motor assistance and 80Nm of torque, the motor closes that gap completely. The 1.31 ratio of the 1×9, combined with the motor, climbs more easily than the 1.00 ratio of the 3×7 without motor assistance.
This is the key insight: the motor changes the math.
Why E-Bike Drivetrains Are Different
Traditional multi-chainring systems exist because human leg power is limited and inconsistent. To stay in a comfortable cadence (around 70–90 pedal revolutions per minute), riders need many small steps between gears to match every terrain change.
An electric motor doesn't have those limitations:
- It produces maximum torque almost immediately
- It maintains consistent power output regardless of pedaling speed
- It compensates for gear ratio gaps by adjusting its own contribution
So while a muscle-powered cyclist genuinely benefits from 21 finely-spaced ratios, an e-cyclist with motor assistance can comfortably ride with only 9 — because the motor fills in the gaps.
This is why every major e-bike motor manufacturer — Bosch, Shimano STEPS, Brose, Bafang — now recommends single-chainring drivetrains in their published technical guidelines for e-MTB design.
The Five Real Advantages of 1×9 on an E-Bike
1. Far Fewer Mechanical Problems
The front derailleur is the most failure-prone component on a traditional drivetrain. It requires precise alignment, gets clogged with mud, and is prone to dropping the chain during shifts under load.
A 1× system eliminates it entirely. One derailleur instead of two. One shifter instead of two. Half the cable runs. Half the adjustment points.
2. No More "Bad Gear Combinations"
On a 3×7 system, certain gear combinations are mechanically harmful — known as cross-chaining. Using the smallest front chainring with the smallest rear cog (or vice versa) bends the chain at extreme angles, accelerating wear on the chain, chainrings, and cassette.
A 1× system has no cross-chaining problems. Every gear combination is mechanically clean.
3. Better Chain Retention
Modern 1× drivetrains use narrow-wide chainrings — chainring teeth alternate in thickness to interlock with the chain's links. This design dramatically reduces chain drops, especially on bumpy terrain.
On a traditional 3× system, hard impacts can throw the chain off the front chainrings, leaving you stranded mid-trail.
4. Less Weight, More Simplicity
Removing the front derailleur, front shifter, two cables, and two extra chainrings saves roughly 300–500 grams. It also simplifies the cockpit (left shifter no longer needed) and reduces visual clutter.
5. Lower Maintenance Cost Over Time
Fewer moving parts means:
- No front derailleur adjustments
- Less cable replacement
- Less frequent chain replacement (no cross-chaining wear)
- Easier home maintenance
For an e-bike owner who rides daily, this translates to real savings — both in service costs and in time spent at the bike shop.
Quick Comparison: 1×9 vs. 3×7 (21-Speed)
For readers who want the summary at a glance:
| Category | 1×9 | 3×7 (21-Speed) |
|---|---|---|
| Mechanical failure rate | Low | High (front derailleur prone to chain drops) |
| Maintenance frequency | Low | High (front derailleur requires adjustment) |
| Chain wear | Even | Uneven (cross-chaining accelerates wear) |
| Weight | Light | Heavier (extra derailleur + shifter + cable) |
| Modern trend | ✅ Industry standard | ❌ Largely phased out on new e-MTBs |
| Beginner-friendly | ✅ Simple (one shifter) | Complex (requires understanding cross-chaining) |
| Pairing with electric motor | ✅ Optimized | Adequate, but not designed for it |
When Does a 21-Speed Still Make Sense?
To be fair, traditional 21-speed drivetrains aren't obsolete in every context. They still have a place on:
- Touring bikes carrying heavy loads on long unpaved tours, where the absolute lowest possible gear matters
- Vintage restorations and entry-level muscle-powered commuter bikes
- Specialty cargo bikes without electric assistance
But for a modern electric mountain bike — designed for daily commutes, weekend trail rides, and moderate off-road exploration — the 1×9 configuration is more reliable, easier to live with, and perfectly capable of handling the steepest grades you're likely to encounter.
What This Means for Your Buying Decision
If you're shopping for an e-MTB and comparing models, here's what we'd suggest looking for instead of obsessing over the gear count:
✅ A wide-range rear cassette — at minimum 32T at the largest cog for climbing capability
✅ A reputable derailleur and shifter brand — Shimano (Altus, Acera, Alivio, Deore tiers) or SRAM (NX, GX) are reliable choices
✅ Motor torque and assistance levels — these have far more impact on climbing than gear count
✅ Matching the bike to your terrain — a 32T cog plus a 500W motor handles 95% of European trail riding without breaking a sweat
❌ Don't be impressed by "21-Speed" as a marketing claim. On an e-bike, it often signals an older drivetrain design carried over from muscle-bike platforms, not a performance advantage.
The Bottom Line
Drivetrain technology in cycling has been moving toward simplicity for over a decade. Professional mountain bikers have ridden 1× systems since the early 2010s. Now, with the rise of electric assistance, that same logic has reached the consumer e-MTB market.
A KINDYMA TITAN X or AURORA S equipped with a 1×9 Shimano drivetrain (42T × 13–32T) and a 500W motor with 80Nm of torque delivers everything most riders actually need: agile climbing, smooth cruising, and reliable, low-maintenance shifting that just works.
Fewer parts. Fewer problems. More riding.
Explore the Models
- KINDYMA TITAN X K01 — 500W motor, 1×9 drivetrain, full suspension. Designed for serious trail riders.
- KINDYMA AURORA S K02 — Step-through frame, 500W motor, 1×9 drivetrain. Built for everyday confidence.
- KINDYMA K03 RANGER — Dual motor, 7-speed wide-range cassette, fat tires. For riders who need maximum torque on the most challenging terrain.
