Befuddled by a technical bike term? Check out our triathlon A-Z bike jargon buster and learn your butts from your bottom brackets!
1in Head Tube
Most road bikes use a 1.125in or larger tapered steerer fork for extra steering stiffness, but some aero bikes use a 1in fork to minimise the frontal area.
Metallic variations on a basic aluminium theme. Bikes normally use 6000 or 7000 series alloys.
Small forward extensions on the handlebar to give an extra hand position.
The profile of a biaxial tube alters along its length. It could be tall and narrow at one end, short and wide at the other.
Spokes which use a flattened centre section to reduce aerodynamic drag.
Threaded inserts on the frame for bolting accessories to.
The bottom section of the frame where the down tube sand seat tube meet and the crank is housed. BB30 bottom brackets are bigger than standard, for greater power delivery.
Screw threaded sections inserted into the cable out for fine adjustment of cable tension.
A sandwich of multiple sheets of woven carbon fibre stuck together with resin, and baked at high pressure to produce a very light, strong structure.
A thin layer of carbon fibre around a metal core. Often just cosmetic.
The two frame tubes which join the bottom bracket area of the frame to the rear dropouts.
A handlebar with a shallower than usual drop and shorter than normal forward reach.
A chainset using smaller (usually 50 and 34 tooth rings) rather than full size 53 and 39 tooth rings, so you’re spinning more than stomping.
Mountain bike-style frame layout using a sloping top tube and long seatpost.
Cross-woven carbon fibre which looks pretty and adds an impact protection layer, but has no actual structural strength.
Short for chromoly. A steel alloy that is stronger than steel. Often used for light tubing.
Winter racing involving reinforced, knobbly tyred road bikes on short off-road courses. Great for off-season training.
Deep Section Wheels
Wheels with a rim deeper than 30mm reduce aerodynamic drag for a faster straightline ride, at the expense of acceleration.
A butted tube has a varied wall thickness to match its strength requirements. A single-butted tube is thicker at one end than in the middle. Double-butted tubes are thicker at both ends.
The slotted tips of the fork and the rear stay that hold the wheel in place.
External Bottom Bracket
Large bottom bracket bearings that sit outside the frame. These work with a hollow axle chainset that’s more convenient to install and lighter and stiffer in use.
Flip Flop Hubs
Where the rear wheel hub is threaded to accept fixed cogs or freewheels on both sides. Enables you to choose between riding fixed or freewheel.
The two main parts of the fork between dropouts that hold the wheel and the crown, which forms the bridge at the top.
Some manufacturers quote frame weight of their smallest size with every fixture removed, but we weight them complete in tested size.
Most frames and forks use alloy dropouts glued into the carbon, but full carbon fibre frames are carbon fibre right through.
The moving components of the bike such as gears and brakes, grouped together based on quality and performance.
Dropouts are the slots in the frame that the wheel axels sit in. Having a horizontal slot rather than the normal vertical one means that you can slide the wheel backwards and forwards.
Shaping frame tubes by squeezing them against moulds with highly pressurised hydraulic oil.
A threaded cable adjuster fitted between sections of the outer cable.
Where the bearings that the fork spins on are housed inside the frame rather than above and below it.
Any structure that carries its stress loads through the outer skin, but often used to describe a frame made of moulded halved rather than glued-together tubes.
Bars designed with a 31.8mm diameter (rather than the standard 27.2mm) to increase stiffness and reduce flex. Must be coupled with an oversize stem.
A metal tube or rod that is the same thickness throughout.
Press Fit BB
Oversized bottom bracket crankset bearings that press directly into the frame to save weight rather than screwing into it.
A skewer with a levered end to hold the wheels in place that can be quickly undone to allow easy wheel removal.
Reversible Seatpost (See also Twin Position Seatpost)
Some frames use a symmetrical seatpost with an offset clamp at the top. By reversing the seatpost front to back you can change the effective seat angle and ride position of the frame quickly and simply.
The angle between the bottom bracket and the saddle. Tri bikes have steep seat angles to help get your back close to horizontal for better aerodynamics.
The removable post upon which the saddle’s rails are bolted and which slides into the seat tube and is fastened by a collar to secure the saddle at the correct height for the rider.
A fork steerer, headset and head tube system where the bottom bearing is larger than the upper bearing, which increases stiffness significantly for a tiny weight gain.
Setting the brakes 1-2mm askew so that the leading edge of the pad hits the rim slightly before the rear.
Screw-on lengths of alloy or carbon that sit on top of the handlebars and allow a more aerodynamic position.
A butted tube has a varied wall thickness to match its strength requirements. Triple-butted tubes have different thickness butts at each end.
Twin Position Seatpost
Gives you the option of either a conventional seat angle – best if you regularly ride conventional bikes – or a steeper seat angle – best for going straight from cycling to running.
Tyres with a wire bead which sits snugly around the rim, encasing an inner tube within.
All-in-one tyres, which don’t require an innertube and must be glued directly onto the wheel’s rim.
A brake that uses a central straddle wire rather than a sidepull configuration.
A curved cut-out on a frame that follows the wheel shape to shield it from the wind.
This is a rear frame design where the two seat stays connect to the frame with a single tube.
Special vibration dampening insets, which Specialized use on their bike frames and other components such as forks and seat posts.