BMX Expert

BMX Expert: the pivotal size, between Expert and Expert +

The Expert class covers riders measuring between 135 and 154 cm, generally aged 10 to 13. This is the size where growth accelerates and where the bike has to be chosen precisely: across a span of nearly 20 cm two frame lengths coexist, and getting it wrong costs a season of approximate position.

Is it the right size for my rider?

Many models exist in both lengths. Between 147 and 154 cm, the overlap with Expert XL is settled on inside leg and build: a long-limbed rider already at ease in a moto gains from the longer frame, while a more compact rider keeps handling on the Expert +. Under 138 cm and in a first race season, a BMX Junior at the top of its range stays more forgiving.

The numbers on an Expert frame

• Top tube 18.5" to 19.5" depending on the Expert or Expert + version
• 20" wheels on 451 rims, 20 x 1-3/8" tyres, as in Mini and Junior
• Cranks from 155 to 165 mm, chosen on leg length and not on age
• 6061-T6 aluminium frames on premium models, carbon forks common
• Disc tab present on the majority of frames in the class
• Euro or Mid bottom bracket shell and a three-piece crankset

Why disc braking takes over at this level

From Expert onwards, speed at the bottom of the hill and the number of motos per weekend change what the brake has to do. A disc gives consistent power in the wet, finer modulation, and does not wear a braking surface on the rim, which matters on carbon rims. Rim brake models stay in the entry-level range, for a controlled budget or mostly recreational use. A 140 or 160 mm rotor and a compatible rear hub are part of the initial choice.

The models available in Expert

Inspyre covers the whole range with the Neo on rim brakes, the aluminium Evo Disk and the Evo-C Disk with carbon fork and wheels. Chase offers the Edge Expert with a triple-butted 6061-T6 frame and disc brake, plus the RSP builds at the top end. Meybo runs the Clipper, the Superclass, the Patron and the HSX builds. Position One holds the entry level on V-brake. At equal top tube, compare bottom bracket height and actual weight: that is where the difference in behaviour sits.

Preparing the move to the Pro classes

Expert and Expert XL are the last sizes on 451 rims. Above 160 cm the rider moves to a BMX Pro on 406 rims, with wider tyres from 20x1.50 to 20x1.75 and a top tube of 20.5" and up. Wheels therefore do not carry over from one class to the next, which is worth knowing before investing in a high-end pair late in Expert.

The BMX RACING advice

Send us the rider's height, inside leg and race class: we settle Expert against Expert +, and confirm crank length and brake type before shipping. The whole sizing chart sits in the BMX bikes and frames section. Dispatched within 24 to 72 hours, you can spread the cost over 2 or 3 payments.

The Expert to Expert XL boundary comes down to a few centimetres; we work it through, tape measure in hand, in our method for choosing a BMX race size.