BULLS Twenty4 E Review: Kids' Electric Mountain Bike

Written by: Chris Van Leuven | August 17, 2026 | Time to read: 6 min

There are plenty of children’s bikes that look like mountain bikes. The Twenty4 E feels like one. Instead of treating younger riders as an afterthought, BULLS built this bike around the way kids actually ride. The 24-inch wheels, lower standover height, and youth-specific geometry make it easier to control on uneven terrain, while the SR Suntour suspension fork and hydraulic disc brakes provide the kind of performance you’d expect on many adult hardtails.

As for the motor, it uses the Bosch Active Line Plus, which produces 50Nm of torque, noticeably less than Bosch’s Performance Line systems. For younger riders, that’s exactly the point. They don’t need fast acceleration. They need predictable assistance, especially on loose climbs, winding trails, and unfamiliar terrain. The result is a bike that builds confidence instead of simply adding speed.

That same philosophy carries over to the bike’s Class 1 setup. Pedal assist cuts out at 20 mph, encouraging kids to keep pedaling and develop good riding habits instead of relying on the motor to do all the work.

Battery size varies by model year, with most bikes using either a 400Wh or 500Wh Bosch PowerPack. Even the smaller battery was never intended to turn kids into endurance racers. Its job is to make longer family rides realistic without every climb becoming a battle. That’s what separates the Twenty4 E from many youth e-Bikes. It isn’t trying to make younger riders faster than everyone else. It simply gives them enough assistance to enjoy rides that might otherwise feel out of reach.

Anyone who’s spent time riding with kids knows how quickly a group can spread out on a long climb. Before long, everyone is waiting at the next trail junction or shortening the route because the youngest rider is running out of energy. The Twenty4 E doesn’t eliminate that challenge, but it makes the difference between cutting the ride short and finishing what you planned.

Parents often ask when a child is ready for an e-Bike, but I don’t think there’s one answer. It depends on maturity, bike-handling skills, and the riding your family enjoys. But if your rides regularly finish with adults waiting at trail junctions or with the youngest rider changing plans because they're exhausted, this is exactly the sort of bike worth checking out.

BULLS also went with quality components, including Bosch’s Active Line Plus system, Shimano’s 8-speed drivetrain, hydraulic disc brakes, and quality suspension, all of which have long service histories. They’re familiar to bike shops, straightforward to maintain, and durable enough to stay in the family as younger siblings grow into them.

That’s a much better investment than buying a cheaper youth e-Bike that’s likely to be outgrown or worn out in just a few seasons.

Not every child needs an electric bike. If most rides happen around the neighborhood or on the way to school, a traditional mountain bike is probably the better choice. The Twenty4 E makes sense when riding becomes something the whole family enjoys together.

Maybe your weekend plans include forest roads, longer rail trails, or rolling singletrack. Maybe one parent rides an e-MTB while another rides a traditional bike. Or maybe your child enjoys riding but starts fading once the climbs begin. That’s when the Twenty4 E starts earning its keep.

Instead of changing every ride into a race, it helps younger riders stay engaged. The Bosch Active Line Plus motor doesn’t overpower the experience. It simply removes enough of the hardest effort that kids can spend more time looking at the trail instead of wondering how much farther they have to climb.

The bike also leaves plenty of room for younger riders to grow. As their skills improve, the suspension, hydraulic brakes, and Shimano drivetrain won’t hold them back. It rides like a real mountain bike because that’s exactly what BULLS intended it to be.

Since the Twenty4 E is no longer part of BULLS’ current U.S. lineup, buying used is how most families will find one. The first thing I’d think about isn’t mileage; it’s fit. Kids grow at different rates, and confidence on the bike matters just as much as height. That’s why a properly fitting Twenty4 E that’s a couple of years older is usually a better choice than a newer bike that’s too large.

From there, confirm exactly which model you’re looking at. BULLS has produced several versions of the Twenty4 E over the years, and battery capacity, drivetrain components, and other specifications can vary by model year.

When I look at a used Twenty4 E, these are the first things I’d inspect:

• Bosch battery health and diagnostic report
• Suspension fork condition
• Brake pad and rotor wear
• Chain and cassette wear
• Charger, battery keys, and available service records

Cosmetic scratches wouldn’t bother me much. Kids tend to ride hard, and trail bikes naturally pick up marks over time. I’d be far more interested in signs that the bike has been maintained. A clean drivetrain, smooth suspension, and documented service history usually tell you much more than the paint.

Buying a youth e-Bike is different from buying one for yourself. You’re not only thinking about reliability, but you also want to know the bike is safe, works properly, and fits the rider it’s intended for.

That’s one reason buying certified pre-owned through Upway makes sense. Every e-Bike goes through a professional 50-point inspection before it’s listed for sale. The frame, suspension, drivetrain, brakes, wheels, battery, motor, display, and electrical system are all checked, giving you a much clearer picture of the bike’s condition than you would get from a typical private sale.

And, each bike also includes a 1-year warranty and a 14-day test ride, giving families time to make sure the fit and riding position are right before fully committing. For a discontinued model like the Twenty4 E, that extra reassurance is a real advantage.