A mother had just bought her son a bicycle. He was going to pay it off by vacuuming the house and cleaning bathrooms weekly. She thought it would be a good lesson about responsibility and working hard to get what you want, and was looking forward to a clean house.
This will not end well.
He's got the bike already. He'll do the chores for a week or two, maybe three. And then what?
The lesson he's learned is that you can have what you want now if you intend to pay for it later. And when he doesn't pay? He'll learn about how easy it is to get out of his responsibilities. He's learned to get into debt, to be a serf to his possessions.
Don't buy the prize first!
Decide in advance how much chore-work the bike is worth. Pay him each week when the work is done. Put the money into a jar, always visible on the counter. Make one of those fundraising thermometer drawings and put it on the fridge. Watch it grow. If he doesn't work, it doesn't grow.
He'll get more and more excited and he'll see the results of his work. Let him go make the purchase.* Let him hand over the cash.
That's the lesson about responsibility and working hard to get what you want: hard work equals results, not I owe, I owe, so off to work I go.
Another suggested approach:
Give him the bike as a gift. Make him earn something else.
*Odd are that by the time he gets the money together, he'll have his eye on some other shiny toy. Or he'll realize he can use some of the money to buy his friend's used bike, and use the rest for something else. Cash is a good thing to have.