{"$schema":"nativecad-dfm-pack/1","id":"bikes","title":"Bikes -- frames, drivetrain, cockpit, e-bikes, scooters and helmets","sector":"bikes","version":"2026-09-03","summary":"Frame tube and bottom-bracket standards, headset and dropout/axle sizing, disc-mount and boss dimensions, cockpit and seatpost diameters, e-bike/scooter/skateboard geometry, and the ISO/EN/CPSC/ASTM tests a bike, e-bike or helmet is held to.","aliases":["bike","bicycle","e-bike","ebike","scooter","e-scooter","skateboard","dropout","bottom bracket","bike headset","seatpost","handlebar","bottle cage","bike rack","helmet","sporting goods","fitness equipment"],"crossSector":false,"size":"core","sources":[{"id":"iso-4210","title":"ISO 4210 (all parts) Cycles -- Safety requirements for bicycles","url":"https://www.iso.org/search.html?q=ISO%204210","accessed":"2026-09-03"},{"id":"en-1078","title":"EN 1078 Helmets for pedal cyclists and for users of skateboards and roller skates","url":"https://standards.iteh.ai/search?q=EN+1078","accessed":"2026-09-03"},{"id":"cpsc-1203","title":"16 CFR 1203 -- CPSC Safety Standard for Bicycle Helmets","url":"https://www.ecfr.gov/current/title-16/chapter-II/subchapter-C/part-1203","accessed":"2026-09-03"},{"id":"iso-6695","title":"ISO 6695 Cycles -- Saddles -- Concepts, dimensions and symbols","url":"https://www.iso.org/search.html?q=ISO%206695","accessed":"2026-09-03"},{"id":"park-tool-standards","title":"Park Tool -- bottom bracket, headset and frame standards reference pages","url":"https://www.parktool.com/en-us/blog/repair-help","accessed":"2026-09-03"},{"id":"sheldon-brown-glossary","title":"Sheldon Brown -- Bicycle Glossary and technical reference pages","url":"https://www.sheldonbrown.com/gloss_a-c.html","accessed":"2026-09-03"},{"id":"shimano-dealer-manual","title":"Shimano Dealer's Manual (bottom bracket, pedal, chainline, freehub specifications)","url":"https://si.shimano.com/","accessed":"2026-09-03"},{"id":"sram-standards","title":"SRAM Standards -- thru-axle and Boost hub/frame spacing reference","url":"https://www.sram.com/en/service/","accessed":"2026-09-03"},{"id":"matweb-materials","title":"MatWeb Material Property Data (frame steels, aluminium, titanium alloys)","url":"https://www.matweb.com/","accessed":"2026-09-03"}],"entries":[{"id":"frame-tube-steel-diameters","kind":"dimension","tier":1,"title":"Steel frame tube diameters and butted wall gauge","summary":"Steel (chromoly) frame tubes run 25.4, 28.6 or 31.8 mm OD, double-butted to a 0.8-0.9 mm centre wall (thicker at the welded ends) -- the standard top/down/seat-tube sizing for a lugged or TIG-welded steel frame.","applies":["frame","top tube","down tube","seat tube","steel frame"],"value":{"options":[25.4,28.6,31.8],"unit":"mm"},"basis":"Common steel-frame tubeset sizing (Reynolds/Columbus-style) referenced across Park Tool and Sheldon Brown frame-building pages","sources":["park-tool-standards","sheldon-brown-glossary"],"tags":["frame","tube","steel","chromoly","diameter"]},{"id":"frame-tube-alloy-diameters","kind":"dimension","tier":1,"title":"Aluminium frame tube diameters and wall gauge","summary":"Aluminium frame tubes oversize to 34.9 or 38.1 mm OD with a 1.2-1.6 mm wall -- larger diameter, thinner wall, trading steel's stiffness-per-weight for aluminium's lower modulus at similar mass.","applies":["frame","top tube","down tube","aluminium frame","alloy frame"],"value":{"options":[34.9,38.1],"unit":"mm"},"basis":"Common aluminium-frame tubeset OD/wall convention (6061/7005 hydroformed and butted tubing)","sources":["park-tool-standards"],"tags":["frame","tube","aluminium","diameter"]},{"id":"bb-shell-bsa","kind":"dimension","tier":1,"title":"BSA threaded bottom bracket shell","summary":"BSA (English) threaded BB shells are 68 mm (road/gravel) or 73 mm (MTB) wide, threaded 1.37 in x 24 TPI -- right (drive) side left-hand thread, left side right-hand thread, so the cups tighten rather than unscrew under pedalling.","applies":["bottom bracket","bb shell","crank"],"value":{"options":[68,73],"unit":"mm","table":[{"field":"thread","value":"1.37in x 24 TPI"}]},"basis":"BSA (British Standard Cycle) threaded bottom bracket shell width and thread convention","sources":["park-tool-standards","shimano-dealer-manual"],"tags":["bottom-bracket","bsa","threaded","shell-width"]},{"id":"bb-shell-pf30","kind":"dimension","tier":1,"title":"PF30 press-fit bottom bracket shell","summary":"PF30 press-fit shells bore to 46 mm ID over a 68 mm shell width, pressing the bearing cups directly into the frame shell rather than threading them -- wider bearing spacing than BSA for a stiffer, lower-friction bottom bracket.","applies":["bottom bracket","bb shell","press fit"],"value":{"table":[{"field":"boreID","value":46},{"field":"shellWidth","value":68}],"unit":"mm"},"basis":"PF30 press-fit bottom bracket standard bore and shell width","sources":["park-tool-standards"],"tags":["bottom-bracket","pf30","press-fit"]},{"id":"bb-shell-t47","kind":"dimension","tier":1,"title":"T47 threaded bottom bracket shell","summary":"T47 threads a 47 mm ID cup directly into a PF30-width (68 or 73 mm) shell -- combining PF30's wide bearing stance with a threaded interface that avoids press-fit creak.","applies":["bottom bracket","bb shell","t47"],"value":{"value":47,"unit":"mm","table":[{"field":"shellWidth","value":"68 or 73"}]},"basis":"T47 threaded bottom bracket standard cup ID and shell width options","sources":["park-tool-standards"],"tags":["bottom-bracket","t47","threaded"]},{"id":"bb-shell-bb86-92","kind":"dimension","tier":1,"title":"BB86/BB92 press-fit bottom bracket shell","summary":"BB86 (road, 86.5 mm shell) and BB92 (MTB, 89.5-92 mm shell) press-fit bearings directly into a 41 mm ID shell bore -- narrower bore than PF30 because the bearings press straight into carbon-moulded cups rather than into an aluminium insert.","applies":["bottom bracket","bb shell","bb86","bb92"],"value":{"value":41,"unit":"mm"},"basis":"Shimano BB86/BB92 press-fit bottom bracket shell bore specification","sources":["shimano-dealer-manual","park-tool-standards"],"tags":["bottom-bracket","bb86","bb92","press-fit"]},{"id":"headset-steerer-diameters","kind":"dimension","tier":1,"title":"Fork steerer diameters: 1-1/8 in straight and 1.5 in tapered lower","summary":"A standard 1-1/8 in steerer is 28.6 mm; a tapered fork's larger lower bearing race seats a 1.5 in (39.8 mm) steerer section, giving the head tube more stiffness where steering loads are highest.","applies":["headset","fork","steerer"],"value":{"table":[{"field":"steerer1-1/8in","value":28.6},{"field":"taperedLower","value":39.8}],"unit":"mm"},"basis":"Standard 1-1/8 in threadless steerer OD and the tapered (1-1/8-to-1.5 in) fork's lower steerer-race diameter","sources":["park-tool-standards","sheldon-brown-glossary"],"tags":["headset","steerer","fork","tapered"]},{"id":"headset-cup-id-table","kind":"dimension","tier":1,"title":"Integrated headset cup/head-tube ID by standard (ZS44/ZS56/IS42/IS52/EC34)","summary":"Head tube or cup ID by integrated headset standard: ZS44 44 mm, ZS56 56 mm, IS42 42 mm, IS52 52 mm, EC34 34 mm -- get the wrong ID and the bearing cup either falls through the head tube or never seats.","applies":["headset","head tube","integrated headset"],"value":{"table":[{"standard":"ZS44","id_mm":44},{"standard":"ZS56","id_mm":56},{"standard":"IS42","id_mm":42},{"standard":"IS52","id_mm":52},{"standard":"EC34","id_mm":34}],"unit":"mm"},"basis":"Common zero-stack (ZS) / integrated (IS) / external-cup (EC) headset head-tube-ID naming convention","sources":["park-tool-standards","sheldon-brown-glossary"],"tags":["headset","zs44","zs56","is42","is52","ec34"]},{"id":"dropout-qr-old","kind":"dimension","tier":1,"title":"Quick-release dropout over-locknut distance and axle diameter","summary":"Quick-release hubs space to 100 mm over-locknut distance (OLD) front, 135 mm rear, on a 9 or 10 mm skewer/axle diameter -- the legacy hub-spacing pair that thru-axle standards replaced.","applies":["dropout","hub","quick release","axle"],"value":{"table":[{"field":"frontOLD","value":100},{"field":"rearOLD","value":135},{"field":"axleDia","value":"9 or 10"}],"unit":"mm"},"basis":"Standard quick-release front/rear over-locknut spacing and skewer diameter","sources":["sheldon-brown-glossary","park-tool-standards"],"tags":["dropout","quick-release","old","axle"]},{"id":"dropout-thru-axle-sizes","kind":"dimension","tier":1,"title":"Thru-axle diameter x OLD combinations and thread pitches","summary":"Thru-axles run 12x100 (front road), 12x142 (rear road/gravel), 12x148 Boost (rear MTB) and 15x110 Boost (front MTB), threaded M12x1.0, M12x1.5 or M12x1.75 depending on brand -- diameter x OLD must match the frame/fork exactly, thread pitch only has to match the axle's own nut.","applies":["dropout","thru axle","hub","boost"],"value":{"options":["12x100","12x142","12x148","15x110"],"unit":"mm","table":[{"field":"threadPitch","value":"M12x1.0 / M12x1.5 / M12x1.75"}]},"basis":"Common thru-axle diameter/OLD combinations and the thread-pitch variation across axle brands","sources":["sram-standards","park-tool-standards"],"tags":["dropout","thru-axle","boost","old"]},{"id":"dropout-hanger-derailleur","kind":"fastener","tier":1,"title":"Derailleur hanger bolt hole","summary":"A rear derailleur hanger mounts on a dia10 mm hole tapped M10x1, threaded into the dropout's replaceable hanger tab -- the hanger is meant to bend or snap before the derailleur or frame does in a chain/spoke strike.","applies":["dropout","derailleur hanger","rear derailleur"],"value":{"value":"M10x1","unit":"mm","table":[{"field":"holeDia","value":10}]},"basis":"Standard replaceable derailleur hanger mounting bolt and hole diameter","sources":["park-tool-standards","sheldon-brown-glossary"],"tags":["dropout","derailleur-hanger","m10"]},{"id":"disc-mount-standards","kind":"dimension","tier":1,"title":"Disc-brake caliper mount standards (IS, post mount, flat mount)","summary":"IS mounts on two M6 bolts 51 mm apart; post mount bolts direct on a 74 mm M6 spacing; flat mount bolts to the frame/fork face on 140 or 160 mm rotor-matched spacing -- an adapter converts between them but never swaps rotor size.","applies":["disc brake","caliper","frame mount","fork mount"],"value":{"table":[{"standard":"IS","spacing_mm":51,"bolt":"M6"},{"standard":"post mount","spacing_mm":74,"bolt":"M6"},{"standard":"flat mount","spacing_mm":"140 or 160"}],"unit":"mm"},"basis":"Common disc-brake caliper mounting standards and their bolt spacing","sources":["park-tool-standards","sram-standards"],"tags":["disc-brake","is-mount","post-mount","flat-mount"]},{"id":"bottle-cage-boss","kind":"fastener","tier":1,"title":"Bottle-cage boss thread and spacing","summary":"A bottle cage bolts to two M5 threaded bosses spaced 64 mm apart on the frame -- the universal bottle-cage mounting standard across steel, aluminium and carbon frames.","applies":["bottle cage","frame boss"],"value":{"value":"M5","unit":"mm","table":[{"field":"spacing","value":64}]},"basis":"Universal bottle-cage boss thread size and hole spacing","sources":["park-tool-standards","sheldon-brown-glossary"],"tags":["bottle-cage","boss","m5"]},{"id":"handlebar-diameters","kind":"dimension","tier":1,"title":"Handlebar grip and clamp diameters","summary":"Handlebar grip area is 22.2 mm; the stem clamp area is 31.8 mm (standard) or 35 mm (oversize, higher-torque MTB stems) -- a stem sized for the wrong clamp diameter cannot torque to spec and will slip.","applies":["handlebar","stem","grip"],"value":{"table":[{"field":"gripDia","value":22.2},{"field":"clampDia31_8","value":31.8},{"field":"clampDia35","value":35}],"unit":"mm"},"basis":"Standard handlebar grip and clamp diameter convention","sources":["park-tool-standards","sheldon-brown-glossary"],"tags":["handlebar","grip","clamp","diameter"]},{"id":"seatpost-diameters","kind":"dimension","tier":1,"title":"Seatpost diameters and frame clamp sizes","summary":"Seatposts run 27.2, 30.9 or 31.6 mm OD to match the frame's seat-tube ID; the external seat-tube clamp collar closes on 31.8 or 34.9 mm -- post diameter and clamp diameter are two different numbers, don't confuse them.","applies":["seatpost","seat tube","seat clamp"],"value":{"options":[27.2,30.9,31.6],"unit":"mm","table":[{"field":"clampDia","value":"31.8 or 34.9"}]},"basis":"Standard seatpost OD sizes and the external seat-clamp collar diameters they pair with","sources":["park-tool-standards","sheldon-brown-glossary"],"tags":["seatpost","diameter","clamp"]},{"id":"saddle-rail-dimensions","kind":"dimension","tier":1,"title":"Saddle rail diameter and spacing","summary":"Standard round saddle rails are dia7 mm, spaced 44 mm apart -- the pair every two-bolt and single-bolt seatpost clamp is machined to grip; carbon/titanium oval or bladed rails deviate and need a matching clamp.","applies":["saddle","seatpost clamp","rails"],"value":{"table":[{"field":"railDia","value":7},{"field":"railSpacing","value":44}],"unit":"mm"},"basis":"ISO 6695 standard round saddle rail diameter and spacing convention","sources":["iso-6695"],"tags":["saddle","rail","iso-6695"]},{"id":"pedal-thread-size","kind":"fastener","tier":1,"title":"Pedal spindle thread: 9/16-20 TPI","summary":"Bicycle pedal spindles thread 9/16 in x 20 TPI into the crank arm -- an inch thread because ISO 4210-8 and pedal manufacturers still publish it that way; the right pedal is right-hand thread, the left pedal is left-hand thread to resist unscrewing under pedalling.","applies":["pedal","crank arm"],"value":{"value":"9/16-20","unit":"in"},"basis":"ISO 4210-8 pedal thread specification, published in inches","sources":["iso-4210","shimano-dealer-manual"],"tags":["pedal","thread","9-16","crank"]},{"id":"helmet-impact-en1078-cpsc","kind":"test","tier":1,"title":"Bicycle helmet impact test (EN 1078 / CPSC 1203)","summary":"Drop the helmeted headform 1500 mm onto flat and kerbstone anvils; EN 1078 and CPSC 1203 both cap transmitted acceleration at 250 g, and CPSC additionally requires the retention strap to hold 500 N without more than 25 mm of extension.","applies":["helmet","bicycle helmet"],"value":{"table":[{"field":"dropHeight_mm","value":1500},{"field":"maxAccel_g","value":250},{"field":"strapLoad_N","value":500}]},"basis":"EN 1078 and CPSC 16 CFR 1203 helmet impact-attenuation and retention-system test requirements","sources":["en-1078","cpsc-1203"],"tags":["test","helmet","impact","en-1078","cpsc-1203"]},{"id":"frame-material-chromoly-4130","kind":"material","tier":1,"title":"4130 chromoly steel frame tubing","summary":"4130 chromoly is the standard steel frame-tube alloy: yield ~460 MPa in the normalized/drawn condition, density 7.85 g/cm3, weldable and butts thin without cracking -- the baseline steel-frame material this pack's tube sizes assume.","applies":["frame","tube","steel"],"value":{"table":[{"property":"yield","value":460,"unit":"MPa"},{"property":"density","value":7.85,"unit":"g/cm3"}]},"basis":"MatWeb 4130 chromoly steel (normalized) property data, the standard bicycle frame steel","sources":["matweb-materials"],"tags":["material","4130","chromoly","steel"]},{"id":"frame-material-aluminum-6061-7005","kind":"material","tier":1,"title":"6061-T6 and 7005 aluminium frame tubing","summary":"6061-T6 (yield ~276 MPa) needs post-weld heat treatment to reach full strength; 7005 (yield ~290 MPa) age-hardens naturally at room temperature after welding -- 7005 is the more common as-welded aluminium frame alloy for exactly that reason.","applies":["frame","tube","aluminium"],"value":{"table":[{"material":"6061-T6","yield_MPa":276},{"material":"7005","yield_MPa":290}]},"basis":"MatWeb 6061-T6 and 7005-T6 aluminium property data, the two common welded bicycle frame alloys","sources":["matweb-materials"],"tags":["material","6061","7005","aluminium"]}]}