DEAR ABBY: Most of us remember spending many pleasurable summer days riding our bicycles through the neighborhood on the way to a friend's house or to the corner store.

Times have changed. That innocent ride can be very dangerous if children do not wear bicycle helmets. Adults often forget that there are more and faster cars on the road than when they were kids. Many think that because they survived the bumps and bruises of childhood, their children will, too. Unfortunately, that's not always the case.Each year 500 children die and more than 380,000 are seriously injured because of collisions while on bicycles. In the United States, more than 50,000 children suffer head injuries in bike-related incidents.

Adults tend to think of bikes as "toys" and, consequently, they do not teach their children to follow the rules of the road. (Most collisions occur as a result of children riding in the street without first looking or yielding to traffic, riding against the flow of traffic, ignoring the rules of the road or swerving suddenly to make a turn.)

Abby, helmets can prevent 85 percent of serious head injuries - they are crucial to the safety of children. Parents should set a good example by wearing bicycle helmets themselves when they ride - with or without their children. Children need to be taught that a bike is a vehicle - not a toy - and, as such, cyclists must follow the rules of the road. Wearing a helmet should be a condition for riding a bicycle, not an option. No helmet - no bike riding!

Bike helmets save lives. What better reason is there to make sure your child wears one? - HERTA B. FEELY, EXECUTIVE DIRECTOR, NATIONAL SAFE KIDS CAMPAIGN, WASHINGTON, D.C.

DEAR HERTA: Thanks for the alert. Let's hope parents and children take heed.

DEAR ABBY: Why do joggers run in the street instead of on the sidewalk?

I nearly killed one the other day; he was running at night, in the street, wearing dark clothes. - FURIOUS IN FALLS CHURCH, VA.

DEAR FURIOUS: I have dealt with this problem several times in an effort to protect not only joggers, but also the motorists who hit them. This is what one motorist had to say back in May 1985:

DEAR ABBY: This evening I came so close to hitting a jogger, my heart is still pounding. In the first place, this idiot was jogging on a dark street at about 11 p.m. He was wearing a black sweatsuit with a hood, and nowhere did he have any reflectors or luminous tape. You can buy that stuff by the yard in any sporting goods shop and sew (or pin) it on your clothing. There are even reflecting shoelaces that light up in the dark.

People that stupid make me sick. Every day, nuts like that are killed by innocent motorists, who then have to carry the unearned guilt around for the rest of their lives. - STILL SHAKING IN VEGAS

- "How to Be Popular" is for everyone who feels left out and wants an improved social life. It's an excellent guide to becoming a better conversationalist and a more attractive person. To order, send a long, business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Popularity Booklet, P.O. Box 447, Mount Morris, IL 61054. (Postage is included.)