Frames

Choosing a BMX race frame: material, geometry and standards

Buying a bare frame means knowing three things: the top tube size that suits the rider, the material that suits how they ride, and above all the mechanical standards that decide whether your current components will bolt back on. That last point is the one that causes the most unpleasant surprises.

7005 aluminium, 6061-T6 or carbon

6061-T6 aluminium is the most widespread alloy in BMX Race. It can be heat-treated after welding, which allows thin, worked tubing — triple-butted tubes, with wall thickness varying along their length. 7005 aluminium is stiffer for the same wall thickness. Carbon drops weight significantly and filters vibration, but it demands torque-wrench assembly and copes poorly with point impacts. In practice: aluminium while the rider is still growing or riding club level, carbon once performance becomes the main criterion.

How to read a frame geometry

• Top tube: the number that names the size, from 15" in Micro to 22" and over in Pro XXXL
• Chainstay length: short for a bike that is lively out of the corners, long to keep the front wheel down out of the gate
• Head angle: slacker stabilises at high speed, steeper makes the bike sharp in a berm
• Bottom bracket height: it sets ground clearance when running long cranks
• Head tube: its length influences the usable rise of the handlebar

Two frames with the same top tube can behave very differently. That is the whole point of a multi-brand catalogue: comparing the real numbers before you buy.

The bottom bracket shell: check this first

Four standards coexist in BMX Race: Euro BB (68 mm threaded), Mid BB (pressed bearings, 41 mm), Spanish BB (pressed bearings, 37 mm) and American BB (51 mm), rarer today. The standard is fixed by the frame: it dictates the bottom bracket you order, never the other way round. Crank spindle diameter, 19 or 22 mm, is then chosen to match.

Dropouts, axle and tensioners

The dropouts set the rear spacing and the axle diameter accepted, 10 mm or 20 mm depending on the level of the frame. Thick machined dropouts hold up better under the torque of a heavy rider. Also check for chain tensioner slots and, if you run a disc, for a disc tab to the right standard. A frame built for V-brake only cannot be converted to disc.

Fork, headset and seat post

The frame dictates the headset type: integrated or semi-integrated, in straight 1"1/8 or tapered. A straight-steerer fork will not fit a tapered head tube. At the front wheel, the fork defines the axle accepted, 10, 15 or 20 mm. Finally, note the seat post diameter expected — 25.4, 27.2 or 31.6 mm — and the matching clamp, which is often not supplied with a bare frame.

The frame brands we stock

Inspyre develops and manufactures its frames in France, with several levels from Junior to Pro. Chase builds its series around triple-butted 6061-T6 aluminium. Meybo, the Dutch reference, runs from club frame to full race frame. Supercross defends geometries oriented towards the gate start. Tangent and Stay Strong complete the offer. All the numbers are broken down size by size in the BMX bikes and frames section, from Mini to Pro XXL.

The BMX RACING advice

Tell us which frame you are replacing and which components you intend to keep: we check compatibility of the bottom bracket shell, headset, rear axle and seat post before shipping, and we tell you what will have to be changed. Dispatched within 24 to 72 hours, you can spread the cost over 2 or 3 payments.