Most of carry around a lot more cash than we realize. Actually, it's "potential" cash.

The average American has some credit cards and, quite possibly, a checking account. The cards and the checks can be lost or stolen just like money. But, unlike cold cash, there are some ground rules that protect your money substitutes.

One of the most recent rules involves automatic teller machines (ATM) cards that you stick into a wall, push a few buttons -- and money comes out.

If a thief gets your card, he can tap right into your bank or savings account, providing he knows your secret identification number or name.

This is why it's not smart to mention your number to strangers or carry it in your wallet or purse. Don't make it easy for crooks.

Under the law, if you report a lost or stolen ATM card within two days of noticing that it's gone, your liability for loss is only $50.

If you wait longer before reporting, your liability jumps to $500. And if your don't notify the bank within 60 days (after you've seen unauthorized withdrawals in your statement), the sky's the limit. You could be liable for thousands of dollars in losses.

The new debit cards that often look just like a bank credit card are listed in the same category as ATM cards and fall under the same rules.

Government banking authorities put the debit cards in with the ATMs even though they're not the same. A debit card is just like a plastic check. When you use it at a store, the money to cover the purchase is drawn right out of your savings or checking account. No credit is involved. In some cases, a debit card can act as an ATM to get cash from automatic teller machines.

With the regular garden variety credit cards your overall liability for loss or theft is limited to $50 per card. And even then you will probably never have to pay.

Many creditors and card issuers don't take the trouble and expense of notifying you of your rights and providing you with an addressed envelope and phone number for notification.

If your don't get this notification and disclosure statement, you are not liable for any money charged on a stolen card.

And if you notify the card issuer immediately after a card is lost or stolen, before any unauthorized transactions have occurred, your are not liable for any subsequent charges.

There is no specific law coverning lost or stolen checks as there is for credit cards and ATM cards. But common law pretty well covers the situation.

If checks are stolen and are used with forged signatures to get at your money, the bank is ultimately liable. Of course, if a store accepts a forged check, the bank bumps it back to the store. Whoever accepts the forged signature is usually the one who gets stuck.

Even so, you can suffer an awful lot of grief if some crook is running around town using your checks. Creditors might well think it's your fault and start harrassing you. It messes up your accounts something awful and it could even put a black mark on your credit rating. If you have been the victim of a check forger, be sure to make an appointment with your local credit bureau (most merchants know the address). You have a right to set the record straight and remove the bad credit rating.

Q. My son's $200 bicycle was stolen from a shopping center last weekend. He locked it and thought it was safe. What's the best way to protect bicycles from thieves?

A. Bicycle thievery is one of the nation's fastest-growing crime statistics. Crooks now have special tools that can cut through the average bicycle lock or chain in seconds.

Police and insurance agents suggest the following steps to protect your bike:

1. Never leave the bike alone, unguarded.

2. Wherever possible, take the bike inside your home, school, office or place of recreation (some stores even allow bicycles inside now).

3. Record your bike's serial number with police and engrave an I.D. number on the bike's frame.

4. Kryptonite and Citadel U-shaped, case-hardened steel locks are among your best buys. These locks are tough and extremely difficult to pick.