Fusing pets in Bike For Egg!: the Fuse Lab guide

The rules, exactly as documented

How a fusion runs

Open the Fuse Lab menu and click three pets of one species. The menu shows the Money cost at the bottom before anything is final. Press Fuse, and the three pets leave your collection at once while the 60 second timer runs. Collect the egg when the timer ends, place it in your pen, and hatch it like any stolen egg. The Lab works at any point in the in game day and night cycle.

Why fuse at all

Fused eggs usually hatch big, and bigger pets earn more, because size multiplies income in this game. Three small duplicates, each earning a trickle, become one heavier pet with a real rate. The mutation rule sharpens the play: one mutated input plus two plain duplicates still produces a mutated egg, so a single lucky roll upgrades a whole fusion instead of being sold or wasted.

Fuse or sell: the duplicate decision

The Sell stall next door pays cash for the same duplicates, and for low earners that cash is small: a recorded bundle of seven low earners returned $86.58K in total. By mid game your placed pets usually earn more than that while you decide, so fusing is normally the better use of Common, Uncommon, Rare and Epic duplicates. Sell when you are short of a specific purchase today; fuse when you are building tomorrow's pen.

The two warnings

First, deletion is permanent. Nothing that enters the Lab comes back, so never fuse a pet your pen depends on for income, and never fuse your only copy of a species you have not yet logged and claimed in the Index. Second, big is usual, not promised: a small hatch from a fused egg is a documented possible outcome. Treat fusion as a strong bet with a known downside, and learn it cheaply first with three Chickens at 1,000 Money, exactly as the game's own coverage suggests.