We headed to Bellingham, Washington, to put the Transition Regulator SX — their newest lightweight eMTB — through a full day of climbing, descending, and jumping. With a claimed weight just over 41 lbs and a 400Wh battery paired to Bosch’s Performance Line SX motor, this bike promises analog-like handling with the benefits of pedal assist.
We rode the higher-end $9,500 build featuring:
- TRP EVO Pro brakes
- RockShox Lyrik Ultimate fork (160mm)
- RockShox Super Deluxe Ultimate shock (150mm)
- OneUp Carbon 35mm rise bar
- Bosch SX motor with 400Wh battery (optional range extender to 650Wh)
First Impressions & Geometry
The Regulator SX feels immediately familiar — nimble, well-balanced, and surprisingly easy to get airborne. Compared to its full-power sibling, the Regulator CX, the SX has a slightly steeper 64.5° head tube angle and no flip chip. While we missed the option to slacken it to 64° for ultra-steep trails, the steeper front end makes the bike more playful and poppy.
Reach, seat tube angle, and cockpit setup are spot-on. Climbing position is excellent — upright, efficient, and comfortable. At 448mm, the chainstays are slightly longer than some other lightweight eMTBs, giving a stable, planted feel through corners and chunder.
Climbing Performance
We rode 22 miles with 4,336 feet of climbing over 4.5 hours, mostly in Bosch’s Blue and Purple modes (eco and trail equivalents). In these modes, we were still working — think Zone 2-3 heart rate — but covering ground at about twice the speed of an analog bike.
For singletrack climbs, Purple mode (eMTB) offered more than enough power without feeling over-assisted. Boost mode was reserved for forest service roads or short, high-output sprints. The range was impressive for a 400Wh battery, and with a range extender, 6,000 feet of climbing seems realistic.
Descending & Handling
This is where the Regulator SX shines.
Jumping
Hands down, this is the best jumping eMTB we’ve ever ridden. It pops naturally off lips, bunny hops easily, and never feels like you’re wrestling extra weight mid-air. Unlike other eMTBs that require altered timing to get airborne, the SX feels identical to a well-balanced analog enduro bike.
Steep & Technical
While the SX handles steep, chunky terrain well, the lack of a slacker head tube option means it’s slightly less forgiving than the CX in plow mode. Where it gives up a bit in stability, it gains in agility — hopping over roots and rocks instead of blasting through them.
Cornering
That long rear end lets you push the front wheel into corners with confidence, keeping the bike composed and hooked up. It’s nimble enough for tight switchbacks but rewards an aggressive rider who likes to load the front end.
Component Highlights
- TRP EVO Pro brakes – powerful, consistent, and confidence-inspiring.
- Bosch SX motor – strong support in Trail/Purple mode, minimal lag. Unfortunately, it’s noisy on descents with a distinct rattle.
- Suspension – balanced, but heavier riders (~195-200 lbs) might notice some flex in the Lyrik vs. a Zeb.
- Tires – stock spec works fine, but softer compounds would better match the bike’s descending prowess.
Downsides
- Motor Noise – The Bosch SX rattle is noticeable, especially on rough descents. It’s a buzzkill on an otherwise dialed bike.
- No Flip Chip – Limits head tube adjustability for steeper terrain.
- Price – At $9,500, it’s premium, but you’re paying for a highly refined ride feel.
Comparisons
We’ve tested the Santa Cruz Heckler SL, YT Decoy SN, and Mondraker Dune. Here’s where the Regulator SX stands:
- Jumping – Best of the group.
- Playfulness – More like an analog bike than any other eMTB tested.
- Steeps – Mondraker Dune still has the edge for ultra-steep descents.
- Motor Preference – Bosch SX over Fazua Ride 60 (used in Heckler SL & Decoy SN) for more natural climbing power.
Who’s the Transition Regulator SX For?
The Transition Regulator SX is for riders who:
- Want an eMTB that feels just like their analog enduro bike.
- Value playfulness, jumping, and cornering agility over raw plow power.
- Are okay putting in some effort and riding mostly in mid-assist modes.
It’s not for:
- Riders who want full-boost laps all day without recharging.
- Those seeking a self-shuttle replacement for maximum vertical in minimal time.
Final Verdict
The Transition Regulator SX is the most intuitive, most jump-happy eMTB we’ve tested to date. It offers an incredibly fun ride for those who prioritize handling over battery size, and its geometry, suspension feel, and component choices make it ready to shred right out of the box.
Just be prepared for the Bosch SX’s motor rattle — if Transition and Bosch could quiet that down, this bike would be near-perfect.
Checkout the Regulator on Transition’s website here
Find our 2025 Best eMTB’s here
Leave a Reply