Spark & Anvil Privacy
A tidy bicycle workshop with a bike on a repair stand, big and small chain gears hanging on a pegboard, wrenches and a sunny open garage door

🚲

SpokeForge

One push of your legs, four spins of the wheel. A bicycle is a machine made of ratios.

🔮 Open the workshop console →

The whole bike is one ratio

Count the teeth on the front gear, count the teeth on the rear, and divide: that’s the gear ratio — how many times the wheel turns for one turn of the pedals. Change it and you change everything a rider feels.

  • ⚙️ Ratio = front ÷ rear. 48 teeth front over 12 rear = 4, so the wheel spins 4 times per pedal. Bigger ratio = harder + faster; smaller = easier + slower.
  • 📏 Distance = ratio × wheel size. A road wheel rolls about 2 metres per turn, so ratio 4 carries you ~8 metres for every push of your legs.
  • 💨 Speed = distance × cadence. Spin those pedals 60 times a minute in that gear and you’re doing about 29 km/h — no motor, just multiplication.

Everything runs on your device — no internet, no accounts.

Meet the crew — the parts that make a bike a machine

  • Chainring is the big front gear — the more teeth it has, the harder and faster the gear it sets.
  • Cog is the little rear gear — the more teeth it has, the easier the gear, for spinning up hills.
  • Cadence (mentor) is the rider’s spin, and reminds the crew that speed is only ever distance-per-pedal times how fast you turn.
  • Brake trades a small pull at the lever for a big squeeze at the wheel — another ratio, working the opposite way.

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