Why Does a Good Bicycle Sell Cheap?

Your child listens; you read. This page is here so you can answer the questions that come after the story. The script itself is available from the script button while the audio plays.

What this episode covers

What happens in a market when the seller knows something the buyer does not.

If good and bad items are mixed together and look identical, buyers offer only a middling price. Owners of good items refuse to sell and withdraw, leaving only the poor ones behind. Nobody in this story is dishonest, and the market still breaks.

The episode closes on two things: this paper was rejected several times before winning a Nobel Prize, and why second-hand markets have not actually collapsed.

What actually happened

• George Akerlof (1940– ), a young economist fresh from his doctorate.
• In 1970 he published "The Market for 'Lemons': Quality Uncertainty and the Market Mechanism" in the Quarterly Journal of Economics. In American usage, a lemon is a used car that keeps breaking down.
• The logic: buyers who cannot judge quality pay only an average price → that price shortchanges good items → good items leave the market → average quality falls → the price falls further. Repeat, and the market shrinks or disappears. This is information asymmetry.
• The paper was rejected by several journals. One rejection amounted to "too trivial"; another, in effect, to "if this were true, economics would have to be rewritten."
• In 2001 Akerlof shared the Nobel Prize in Economics with Michael Spence and Joseph Stiglitz.
• The paper contains a section on remedies — the table of contents lists IV. Counteracting institutions: guarantees, brand reputation, licensing and the like.

Questions your child may ask

"If nobody is bad, why does it get worse?" This is the heart of the episode. Everyone made the choice that suited them, and the result was worse for all. The owner of a good bicycle keeping it, and the buyer offering a middling price, are both perfectly sensible. This is a chance to shift from "who is at fault" to "how is this set up."

"So we shouldn't buy second-hand?" The opposite. Second-hand markets work precisely because people built ways of making quality visible — guarantees, reviews, certification, shop reputation. Star ratings on a resale app are the version your child already knows.

"Why does a guarantee help?" Because someone selling a bad item cannot afford to offer one. So being able to offer a guarantee is itself evidence that the item is sound. Economists call that a signal.

"If a paper gets rejected, doesn't that mean it's wrong?" A good question. Peer review is done by people, and people get it wrong. Akerlof's paper was rejected repeatedly and later won a Nobel Prize. Papers that are published are sometimes later shown to be mistaken. Review is not a perfect filter — it is one filter among several.

"Does this happen at school?" It does. In group work, if nobody can see who did how much, the person who worked hardest loses out. That is why teachers ask for role sheets or progress notes. Naming that connection brings the idea into your child's own world.

Ideas inside the story

• Information asymmetry — one side knows, the other does not.
• Adverse selection — the good side leaves first, and what remains gets worse.
• Signals and institutions — guarantees, reputation and certification make the unknown knowable.

What is evidence, and what is received story

Verifiable in the paper Publication in QJE 84(3), pages 488–500, the model built on automobiles, and the fact that section IV addresses counteracting institutions. This paper has no abstract — in our own Shoulders of Giants entry the abstract field contains only the table of contents. So this episode draws on the argument of the paper and on well-established accounts, and quotes no abstract.

Widely reported anecdote The rejections and the reasons given have been recounted by Akerlof himself on several occasions and are widely cited. But which journal used exactly which words varies between retellings, so no journal is named in the story.

Simplified Used cars became bicycles — far closer to a child's world. "Lemon" is an American expression, so the story explains it as it goes.

Sources and what followed

Original paper — George A. Akerlof, "The Market for 'Lemons': Quality Uncertainty and the Market Mechanism," Quarterly Journal of Economics 84(3), 1970. Listed in Paperis' Shoulders of Giants under economics.

What this paper led to

• The economics of information — Spence's signalling theory (why a diploma is a signal) and Stiglitz's screening theory, bundled together in the 2001 Nobel Prize.
• Everyday institutions — certified used cars, product warranties, online reviews and ratings, licences and qualifications. All of them exist to narrow the information gap.
• Insurance and finance — the same structure appears when an insurer cannot tell who is risky, and it is used in analysing financial crises.

Try this together

• Play the lemon market at home. Put a sweet under three of six upside-down cups. Ask your child how much they would pay for one cup. Then repeat with see-through cups. The effect of information on price appears immediately.
• Open a resale app together and talk about why reviews and star ratings are there.
• The next time your child sells or gives something away, ask: "How will the other person know this is good?"