Trek 4300 Disc kids’ bike review

Tiny hardtail has it where it counts

Our rating 
3.5 out of 5 star rating 3.5
GBP £425.00 RRP | USD $682.00
Trek 4300 Disc kids bike

Our review

A deceptively capable singletrack bike for entry-level riders of any size
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Trek’s 4300 Disc is a decent entry-level bike for adults in larger sizes and despite its unprepossessing paintjob, in the 13in size it stands up well as a junior bike.


The fork is one of the best we’ve tested at this price, and the frame has useful features like a lower bottom bracket and big clearances. With shorter cranks and some hand-me-down equipment, this could be a corker.

Ride & handling: Could be lighter, but fork is good and there’s plenty of growing room

The Trek’s RST Gila fork comes with a lockout and fixed rebound damping. While the travel is limited to around 50mm, the movement you do get is fairly plush and controlled. There’s little stiction on the way down and it doesn’t just fire back at you on the way up or have that horrible running-on-a-trampoline feel when you run into repeat hits. “Smoother,” said our young testers.

One of them nearly washed out on a fast corner. That’s a product of two things, both of which are easily changed. First is bar height: the Trek comes set up with a poker chip stack of spacer washers on the top, giving a higher bar and hence a lighter loaded front end. Flipping the step and moving the spacer washers is an easy job, and it’s nice to have the option to run bars either high or low.

Second is the Bontrager Jones XR tyres. Their light tread will do fine for casual street riding or dry summer trails, but when you want tyres that will hook up in a range of conditions you want something with a bit more bite. Panaracer Fire XCs are a good cost/performance compromise if you want to upgrade.

A lower bottom bracket than rivals like the Specialized P1 AM and Saracen Mantra makes the 4300 Disc a better option for kids, while the long seatpost and steerer mean more growing room as they get taller.

Frame: Well-designed chassis with plenty of mud clearance

The testers were sniffy about the paintjob but the ugliness is only skin deep: the pipework is all good. The big down tube is biaxially ovalised to deal with the different stresses at head tube and bottom bracket. At the top there’s a reinforcing curve, like the Specialized ORE bend, while at the bottom it’s squared off to give a good weld area. Because it’s a small frame with chunky tubes, there’s a big welded overlap as the top and down tubes meet at the hourglass head tube.

Since the rear triangle is smaller too, there’s no space for the top part of the wishbone at the seatstays. Space around the tyre, however, has not been compromised, either here or at the chainstays: there’s masses of room. Want to fit a 2.5in tyre? No problem.

A small wedge in the apex of the seatstays carries an eyelet that could be used for a three-point fitting rear carrier. You’ll struggle to fit one or a rear mudguard though, because the cable disc’s calliper obstructs the offside eyelet near the dropouts.

Equipment: Great wheels for a budget bike, but brakes are spongy and cranks are over-long

The ‘TNL’ suffix tells you that you can ‘Turn ’N’ Lockout’ the RST Gila fork. The hydraulic cartridge in one leg damps the rebound and while it can’t be adjusted, it can be locked out completely for roadwork or climbing. You can preload the coil spring in the other leg.

Cranks are too long at 170mm. That’s better than 175mm on a 13in frame, but there’s no excuse not to have 165mm. Shorter would be better still. Gear range is good, though a 34T sprocket at the back would make climbing easier. Big jockey wheels on the Alivio rear mech should turn with less friction when the chain becomes claggy.


The wheels are very nice for a budget bike. Shimano disc hubs are laced to doublewall Bontrager Ranger aluminium rims with brass eyelets – which should make them less susceptible to cracking at the spoke holes. The 4300 is also available with V-brakes and non-disc hubs for around £50 less.

Product Specifications


Name 4300 Disc (10)
Brand Trek

Available Sizes 13 Inches 16 Inches 18 Inches 19.5 Inches 21 Inches 22.5Inches 24 Inches
Headset Type VP-A42E threadless, 1.125in semi-integrated
Weight (lb) 31
Stem SSR, 80mm
Shifters EF50 8-speed
Seatpost SSR aluminium micro-adjust
Saddle Race Lux
Rims Ranger rim, 32 hole
Rear Tyre Size 26x2.0
Rear Tyre Bontrager Jones
Rear Hub RM65
Rear Derailleur Alivio
Pedals Platform
Handlebar SSR aluminium riser, 600mm (23.6in)
Bottom Bracket Cartridge, square taper
Grips/Tape SSR
Front Tyre Size 26x2.25
Front Tyre Bontrager Jones
Front Hub FM65
Front Derailleur Altus
Frame Material Alpha aluminium
Fork Gila TNL coil, 100mm travel
Cranks M311, 170mm, 22/32/42T
Chain HG50
Cassette SRAM PG830 8-speed, 11-32T
Brakes 416 mechanical disc
Brake Levers Shimano EF50