Work it out.
Calculators
Displacement (engine size)
Geometri (cylindervolumen)
Gear development (metres per pedal revolution)
Forholdsregning + cirkelomkreds
Speed at cadence
Forholdsregning + enhedsomregning
Chain length
Branchestandard (kædelængdeformel, Park Tool / Sheldon Brown)
Compression ratio
Geometri (motorteknik – kompressionsforhold)
Mean piston speed
Motorteknik (middel stempelhastighed – standardformel)
Chain wear in per cent
Branchestandard (kædeslidsmåler, fx Park Tool CC-3.2/4.2 — målt over 12 tommer/304,8 mm)
Speedometer and legal deviation
UNECE R39 / EU-typegodkendelse (hastighedsmålertolerance: 0 ≤ V1−V2 ≤ 0,1×V2+4 km/t)
E-bike range
Fysik (energiligning W = U x I) + producentdata (forbrug Wh/km)
Gear ratio spread (range)
Branchestandard (drivline-udvekslingsspredning, fx SRAM/Shimano kassettemarkedsføring)
Saddle height (LeMond method)
Cykel-fitting (LeMond-metoden)
Brake disc wear limit
Producentdata (min. tykkelse stemplet på bremseskiven)
Power-to-weight ratio (A2 licence)
Kørekortbekendtgørelsen / EU-direktiv 2006/126/EF (kategori A2: maks. 35 kW og 0,2 kW/kg)
Tread depth and legal requirements
Lovkrav (Bekendtgørelse om køretøjers indretning og udstyr, BEK nr. 855/2020 — min. 1,0 mm for motorcykel/knallert)
Brake fluid — boiling point and margin
SAE J1703/J1704 + FMVSS 116 / ISO 4925 (DOT-bremsevæskeklasser, tørt/vådt kogepunkt)
Spindle length
Geometry (cosine law same formula as DT Swiss and Sheldon Brown spoke calculators)
Steering geometry: trail
Geometry (overhang = (R × cos steering angle − offset) ÷ sin steering angle)
Hydraulic brake: pressure and brake torque
Physics: p = F ÷ A (Pascal's law) · braking torque = 2 × µ × F × r
Tools that work in all subjects
Whatever your programme is called, these tools calculate the same — Pythagoras, area, percentages and units are not tied to one trade.
- Pythagorasa² + b² = c²Find the missing side, set out a right angle, check whether a room is square, and find the space diagonal.
- Area and perimeterm²Rectangle, triangle, trapezium, circle and composite shapes — area and perimeter.
- Volume and surface aream³ · lBox, cylinder, cone, sphere, pyramid, prism, pipe and frustum — also in litres.
- Percent%Percentage of, how many per cent, percentage change, discount and VAT.
- Scale and ratios1 : 50From drawing to reality, area and volume to scale, the rule of three and dividing in a ratio.
- Unit convertermm ↔ mFrom mm to km, Pa to bar and kB to GB — with the unit staircase.
- Time calculations and the clockt : minTime between two clock times, add time, and 1.75 h = 1 h 45 min for the timesheet.
- Slope and fall% · ° · 1:xFall from level to level, in per cent, per mille, degrees and mm per metre — and the height difference.
- Material consumption including wastem² + %Boards, paint, battens at c/c spacing and packs — for a composite surface or a whole room, with waste.