Glossary
Cyclocross glossary
28 terms from frame geometry through Di2 shifting to race rules. Each term also shows its Hungarian equivalent. The definitions come from the research behind the Ciklobike emulator.
Frame geometry
- Stack (frame stack height)
- Vertical distance from the centre of the bottom bracket to the top centre of the head tube. More stack means a higher handlebar and a more upright position.
- In Hungarian: Stack
- Reach (frame reach)
- Horizontal distance from the centre of the bottom bracket to the top centre of the head tube. Together with stack, it is the most reliable way to compare frame sizes across brands.
- In Hungarian: Reach
- Trail (steering trail)
- Distance along the ground between where the steering axis meets the ground and the front tyre’s contact point behind it. Head angle, fork offset and wheel size set it: more trail gives steadier steering, less trail gives quicker steering.
- In Hungarian: Utánfutás
- Fork offset (rake)
- Perpendicular distance between the steering axis and the front axle. At the same head angle, more offset means less trail and lighter steering.
- In Hungarian: Villa előrenyúlása
- Head tube angle
- Angle of the head tube (steering axis) measured from the horizontal. A steeper angle sharpens steering and a slacker angle adds stability; cyclocross frames are usually steeper and quicker than gravel frames.
- In Hungarian: Fejcsőszög
- BB drop (bottom-bracket drop)
- How far the bottom-bracket centre sits below the line joining the two wheel axles. Cyclocross frames use less drop than road frames, often roughly 60–70 mm against about 70–75 mm. The higher bottom bracket leaves pedal clearance in ruts and corners.
- In Hungarian: Középcsapágy-süllyedés
Position and bike fit
- Crank length
- Distance from the centre of the bottom-bracket axle to the centre of the pedal axle. Most adult cranks are 165–180 mm (GRX RX820: 170, 172.5 and 175 mm); shorter cranks open the hip angle and add ground clearance.
- In Hungarian: Hajtókarhossz
- Stem (handlebar stem)
- The part that clamps the handlebar to the fork steerer. Its length and angle move the bar forward or back and up or down, so how far and how high the bar sits can be fine-tuned without changing the frame.
- In Hungarian: Kormányszár
- Saddle setback (setback)
- How far the saddle sits horizontally behind the bottom-bracket centre. Seat-tube angle, seatpost offset and where the saddle rails are clamped set it. It decides where the rider’s weight and knees sit relative to the pedals.
- In Hungarian: Nyereg-hátratolás
- KOPS (Knee Over Pedal Spindle)
- A classic bike-fit rule of thumb: with the cranks horizontal, a plumb line from the front of the knee (just below the kneecap) should pass through the pedal axle. It is a starting point for saddle fore-aft position, not a law.
- In Hungarian: KOPS
- LeMond saddle height
- A common starting point for saddle height: inseam × 0.883, measured from the bottom-bracket centre to the top of the saddle. The Ciklobike crash-test dummy computes this value too; the body and the shoe–pedal system refine the final setting.
- In Hungarian: LeMond-féle nyeregmagasság
Drivetrain and shifting
- Chainline
- Sideways distance from the bike’s centre plane to the middle of the chainrings (or to a given cog). A correct chainline keeps chain angles small for quiet, efficient shifting; road cranks are typically about 43.5 mm (for example Shimano 105 FC-R7000).
- In Hungarian: Láncvonal
- Q-factor
- Distance between the outer faces of the two crank arms where the pedals attach. It sets how far apart the feet are; Shimano 105 FC-R7000, for example, measures 146 mm.
- In Hungarian: Q-faktor
- Di2 (Shimano electronic shifting)
- Digital Integrated Intelligence: Shimano’s electronic shifting, introduced in 2009 with Dura-Ace 7970. Buttons send signals and motors move the derailleurs. GRX Di2 is the gravel and cyclocross family; the 12-speed RX825 (2024) uses wireless shift levers and a central battery.
- In Hungarian: Di2
- Shadow RD+
- Shimano’s low-profile rear derailleur design, which tucks closer under the cassette so it is less exposed to impacts. The “+” adds a switchable chain stabiliser (clutch) that keeps the chain tense so it does not slap or drop on rough ground; GRX RX825 has an on/off switch.
- In Hungarian: Shadow RD+ hátsó váltó
- Cassette (rear cogs)
- The stack of rear cogs that slides onto the hub’s freehub body. A cog with more teeth gives an easier gear; GRX Di2 12-speed uses, for example, 11–34T or 11–36T cassettes.
- In Hungarian: Fogaskoszorú
- Shift-brake lever (STI)
- A drop-bar unit that combines brake lever and shifter (STI: Shimano Total Integration). On GRX Di2 it holds the shift buttons and, with hydraulic brakes, the master cylinder; its hood is the rider’s most-used hand position.
- In Hungarian: Fékváltókar
Brakes, wheels, tyres
- Hydraulic disc brake
- A brake in which fluid (mineral oil in Shimano systems) carries lever force to caliper pistons, which clamp pads onto a rotor at the hub. Strong, easy to modulate and unaffected by mud on the rim; allowed in UCI cyclocross since 2010.
- In Hungarian: Hidraulikus tárcsafék
- Flat mount (caliper mount standard)
- A disc-brake caliper mounting standard developed by Shimano for road, gravel and cyclocross frames. The caliper sits flat on the chainstay or fork and is bolted from below, a compact, clean fit for 140 and 160 mm rotors.
- In Hungarian: Flat mount
- Thru-axle
- An axle that passes through the hub and threads into the frame or fork instead of a quick-release skewer. It is stiffer and keeps the rotor precisely aligned; typical cyclocross and gravel sizes are 12×100 mm front and 12×142 mm rear.
- In Hungarian: Átütőtengely
- Tubular tyre (tub)
- A tyre whose casing is sewn closed around an inner tube and glued or taped onto a dedicated tubular rim. It was long the pro cyclocross standard because it grips at low pressure, rides supple and can still be ridden when flat; tubeless is now a common alternative.
- In Hungarian: Csőgumi
Racing and rules
- UCI 33 mm tyre rule
- UCI equipment rule 1.3.018: in cyclo-cross a tyre may be at most 33 mm wide, measured at its widest point, and may not have spikes or studs. In force at UCI-sanctioned races since 2010.
- In Hungarian: UCI 33 mm-es gumiszabály
- Pit (bike exchange)
- A technical zone on a cyclocross course, reached once or twice per lap. Riders swap to a clean spare bike there while mechanics pressure-wash the muddy one.
- In Hungarian: Depó
- Drop bar (road handlebar)
- A road-style handlebar whose ends curve forward and down, giving the rider three hand positions: tops, hoods and drops. Standard on cyclocross bikes; gravel bars often also flare outwards.
- In Hungarian: Hajlított kormány
Drawing and modelling
- Exploded view
- A technical illustration in which an assembly’s parts are pulled apart along their assembly axes while keeping their relative position and order. It shows what each part is and how it fits.
- In Hungarian: Robbantott ábra
- Procedural modelling
- Creating 3D geometry with code (functions, parameters, curves and sweeps) instead of sculpting or scanning. When a parameter such as frame size or tooth count changes, the model rebuilds consistently.
- In Hungarian: Procedurális modellezés
- Emulator
- A program that reproduces how a real system works and behaves. Ciklobike emulates the bike’s mechanics (drive, freewheel, shifting, braking) but does not compute full vehicle physics the way a simulator does.
- In Hungarian: Emulátor
- Crash-test dummy (Hybrid III)
- The standard human-sized dummy used in crash tests. Ciklobike uses three Hybrid III sizes (5th percentile female, 50th and 95th percentile male), so a bike set-up can be judged against known body dimensions.
- In Hungarian: Töréstesztbábu