BMX Expert XL

BMX Expert XL: the last size on 451 rims

The Expert XL class takes riders measuring between 147 and 160 cm, generally aged 12 to 15. It is the longest size offered on 20 inch wheels in the 451 format: straight after it, the move to Pro forces a complete change of wheel format. Choosing this size therefore also decides how long the build will last.

Is it the right size for my rider?

Between 147 and 154 cm, Expert + and Expert XL overlap. The useful marker is inside leg rather than height: a long-limbed rider is already comfortable on a 19.5" top tube, while a more compact build keeps its sharpness on a BMX Expert. Above 158 cm and in the middle of a growth spurt, look straight at the BMX Pro range rather than buying an Expert XL for six months.

The numbers on an Expert XL frame

• Top tube 19.5" to 20", the longest figure in the 451 format
• 20" wheels on 451 rims, 20 x 1-3/8" tyres
• Cranks from 165 to 170 mm, already close to adult lengths
• 6061-T6 aluminium frames, carbon forks common at this level
• Disc tab almost universal, 140 or 160 mm rotor
• Slightly longer chainstays to settle the bike at high speed

451 then 406: what the change involves

Expert XL is the last class on 451 rims, with narrow 20 x 1-3/8" tyres cut for speed and low weight. In Pro you switch to 406 rims and tyres from 20x1.50 to 20x1.75, wider, higher in volume, better matched to the power of an adult rider. The two formats share no tyres, no inner tubes and no rims: a pair of Expert XL wheels will not go back on a Pro frame. That weighs on whether or not to invest in carbon wheels late in the class.

Disc braking: the standard of the class

At this speed, discs are fitted to almost every race bike. Power does not fade in the wet, modulation lets the rider brake late into a berm, and the rim is no longer a friction surface. A few entry-level models keep the V-brake: a coherent choice for training, provided the pads are kept fresh.

The models available in Expert XL

Inspyre offers the Neo on rim brakes at entry level, the aluminium Evo Disk, the Evo-C Disk with carbon fork and wheels, and the Concorde for the most developed builds. Chase runs the Edge Expert XL with a triple-butted 6061-T6 frame, carbon fork and disc brake. Meybo covers the class from the TLNT to the Patron, by way of the Clipper and the Superclass.

Adapting the build to growth

In this age bracket the body changes fast. Three adjustments follow growth without changing the frame: saddle height, headset spacers under the stem, and handlebar rise. Cranks that are too short, on the other hand, limit power out of the gate: that is usually the first component to move on.

The BMX RACING advice

Send us the rider's height, inside leg and season plans: we arbitrate between Expert +, Expert XL and Pro, and confirm cranks and braking before shipping. The full chart is in the BMX bikes and frames section. Dispatched within 24 to 72 hours, you can spread the cost over 2 or 3 payments.

Moving up to Pro also changes the wheel format: our article on BMX race frame sizes spells out what transfers to the new frame and what has to be bought again.