ByK E-350x3i MTR Review

The ByK E350x3i‘s coaster brake and 3-speed internally geared hub are easy to use, but the bike is a challenge to assemble. Read the review below for all the details.

child riding a ByK 350x3i kids bike

ByK E-350x3i Review

RATING: Recommended

MSRP: $319

BEST FOR: Neighborhood riders who need gears at a young age

SEAT HEIGHT: 18.1″ – 23.2″

WEIGHT: 19.4 lb.

GEARS: 3/Internally-geared Shimano Nexus Hub
BRAKE: Coaster brake with Front Hand Brake


  • Easy to use 3-speed internally-geared hub
  • Lightweight for its price range


  • Challenging to assemble, does not come with tools or instructions
  • Quality of components could use improvement
  • Poor quality caliper front brake

ByK E350x3i Review – Results of our Test Rides

With a unique mix of features, the ByK E-350x3i is a fun little bike for 4 to 6-year-olds to ride around the neighborhood.  Not too technical and not too advanced, its internally-geared hub is an effortless introduction to gears, while its coaster brake allows for a stopping mechanism many kids are already accustomed to.

While certainly not a favorite of our young testers, as the smallest geared bike we’ve ever tested, the 350x3i is a notable option for small riders who are riding on terrains where gears will be helpful.

Size and Weight

The 350x3i has a seat height of 18″ – 23″ and is a great fit for kids in size 4T and 5 pants.  We tested the 350x3i with a four-year-old in size 4T pants and a six-year-old in size 5 pants, who both fit great on the bike.  Our seven-year-old tester in size 7 clothes also enjoyed his ride, but he was technically too large for the bike. For more information on how to find the right bike size for your child, check out our bike sizing guide where we walk you through 5 simple steps in finding the best fit.

Weighing in at 17.2 lb., the bike was easily maneuvered up bike ramps and over curbs by our experienced riders.  Due to the gearing and braking system of the bike, however, we do not recommend the 350x3i as a first-time pedal bike for young riders.  The single-speed ByK E-350 would be a better choice for beginning riders as learning to ride a bike is challenging enough without the added complexity of gears.

ByK 350x3i in Action

Young boys riding the ByK E-350x3i kid's bike in silver

Internally Geared Hub

The ByK E-350x3i’s 3-speed internal hub is the bike’s standout feature and main selling point.  We love internally-geared bikes for young riders, especially the Shimano Nexus hub which the 350x3i features.  Internally-geared hubs allow bikes to have gears, but without a derailleur.  Derailleurs are notoriously finicky, need regular maintenance, and sit really low to the ground on kids’ bikes, which causes them to get damaged easily.

Additional Clearance with Internally-Geared Hubs

Comparison showing little clearance with a traditional derailleur on a kid's bike, vs more clearance on a bike with an internally geared hub

With an internally-geared hub, the gears are inside the hub of the bike (where the spokes meet in the center of the wheel), so they are MUCH less likely to get damaged and require very little maintenance.  On the outside of the rear axle, there is a small component (the bell crank unit) that tells the hub which gear to be in, but it is protected by a cage.

Internally-Geared Hub’s Outer Components

ByK E-350x3i's bell crank unit is the part that selects the gear and is surrounded by a protective cage. The internally geared hub is where the gears actually change in the ByK E-350x3i.


Shifting an internally-geared hub is very easy and straightforward.  Kids simply twist the inner portion of the right handlebar grip either forward or backward.  With only three gears to choose from, we found our younger testers prefer the simplicity of 3 gears versus getting lost in 6 or 7 gears.  As an added bonus, unlike traditional shifting systems on bikes, kids can shift an internally-geared hub at any time, even while the bike is at rest, without worrying about causing the derailleur to get out of alignment.

The shifters on the ByK 350x3i have a viewing window that visually shows a 1, 2, or 3 so that kids can easily tell which gear they are in.  The window on the shifter, unfortunately, did crack during a crash but the damage was only on the surface and did not affect the shifter’s performance.

Additionally, our testers found the window view shifter hard to read due to the glare from the sun.  As a result, they preferred a standard view shifter, like that found on the Priority.

Differences in Gearing Indicators on Shifters

1) Window view shifter on ByK hard to read with glare from the sun. 2) Standard view shifter is easier to read on the Priority bike. 3) Window of shifter on ByK E-350x3i cracked during a crash.


The ByK comes with dual-hand brakes as well as a coaster brake.  While the coaster brake would normally be duplicative, we found it to be necessary as the handbrakes on the ByK were challenging to use for our 4 and 6-year-old testers.  The main issue is that the placement of the shifter causes the brake lever to be set further in on the handlebars.

To reach the brakes, the child has to reach at an angle, which was a stretch for small hands.  The brake lever can be adjusted closer to the handlebars, but it still required our testers to loosen their grip on the handlebars to reach the levers.

Long Reach for Brake Levers

Brake lever on ByK E-350x3i is a bit difficult for small hands to reach.

The front brake on the bike was also problematic because it’s a lower performing caliper brake versus a v-brake.  While some caliper brakes do a decent job, in general caliper brakes are not nearly as effective as v-brakes and rarely stay properly aligned.  The main problem is that caliper brakes only mount to the top of the fork, not the sides, so they easily shift side to side and get out of place.  Even with proper adjusting, we were not able to get the front caliper brake to work nearly as well as the rear v-pull brake on the 350x3i.

V-brakes (like the rear brake on the ByK) mount on both sides of the fork and are much less prone to shifting out of place and are much more reliable than caliper brakes.  Due to the special mounts required on a fork to mount a v-brake, caliper brakes are often used to save on costs.

Caliper Brakes vs. V-Brakes

Front caliper brake on ByK E-350x3i is attached only at the top of the fork, which rarely stays properly aligned. Front V-Pull brake On Priority Start attaches to both sides of the fork, and is rarely out of alignment. The rear v-pull brake on the ByK E-350x3i is higher quality than its front caliper brake.


With a garage full of kids’ bikes, we’re pretty confident in our bike assembly skills, but the ByK was a bit challenging for us to assemble.  Not only did the bike come without tools or any real instructions, but it also appeared to be shipped directly from the factory without final tuning or tightening of bolts. 

A lack of tuning is common with other low and mid-range brands such as Schwinn or Diamondback, but this is first time tools for assembly as well as proper instructions have not been included. As a result, if you’re not familiar with assembling a bike (including adjusting brakes), or if you don’t have tools, we recommend having the bike assembled at a bike shop.

Various Tools are Needed (and not included) to Assemble the ByK

Headset, wheel axle, and brake require special tools (not included) for assembly of ByK E-350x3i.

For those ready to tackle assembly, here’s the list of required tools as listed in the owner’s manual: 5-10cm and 32 cm adjustable wrenches, 15mm flathead screwdriver, 15mm Phillips screwdriver, 2-8 mm Allen wrench set, set of open end spanners 7-17mm, set of tire levers, chain link remover, wire cutters, and a torque wrench.


The ByK E-350x3i is a unique bike and doesn’t have a direct comparison (that is widely available).  Several kids bikes are available with internally-geared hubs, but they are on larger 20″ or 24″ bikes.  As we mentioned previously, if your young rider needs gears, the ByK E-350x3i is really your only option.  If you’re open to a single-geared bike, the ByK E-350 single-speed and the Priority Start 16 are similar in size and price.

ByK E-350x3i: Best for young riders who need the flexibility of gears.

ByK E-350: Geared slightly higher than other bikes its size, the ByK is best for riding on pavement without much change in elevation.

Priority Start 16:  By far the best quality for the price.  Offers more upright body positioning, which timid or beginning riders prefer.

ByK E-350x3i Comparisons

Model (link to review) ByK 350x3i ByK E-350 Priority Start 16
Price $349 $309 $329
Gearing 3-speed Internal Single Single
Seat Height 18" - 23" 18" - 23" 19" – 23.5"
Weight 19.4 lb. 17.2 lb. 17 lb.
Front Brake Caliper Caliper V-brake
Rear Brake V-brake, coaster V-brake, coaster V-brake, no coaster

ByK 350x3i Bike Bottom Line

The ByK E-350x3i is a uniquely small geared bike that is certainly fun for ages 4 to 6, but its difficult assembly and lower quality front brake limit its appeal.

FTC Disclosure: Affiliate links are included in this review.  No monetary compensation was provided for this review, however, the reviewed product was supplied by the manufacturer or distributor to help facilitate this review. All opinions and images are that of Two Wheeling Tots LLC.  All content and images are copyrighted and should not be used or replicated in any way. View our Terms of Use.

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