Nobody in the injury prevention field recommends taking an infant of less than 12 months in a bicycle child seat, trailer, sidecar or any other carrier. Nobody. And we do not either.

That statement explains why you will not find a child helmet on the market sized for a tiny tot. You certainly do not want to ride with a bare-headed child, and in some places it is illegal. In fact, several states have laws against taking children under one year of age on a bicycle, even with a helmet.

Parents love their babies and love their bicycles, so it is natural to want to put the two together. That thought occurs to every bicycling parent, generally before the child is born. We see messages on the Internet indicating that some parents do put their children in baby seats of one design or another and take them along on trailers starting as young as six weeks. Others use a baby backpack. At slightly older ages, people use front or rear-mounted child seats. A few (mostly in the UK) use sidecars. Each has its advantages and disadvantages. A disclaimer: our purpose here is to cover the risks, so you know what you are getting into. We are hearing more these days about undiagnosed brain injuries, with symptoms too subtle for doctors to detect, but very real to families. And that comes to mind whenever someone asks us about babies and biking. We worry about your six-week-old entering the first grade six years from now with a mental handicap. That is alarmist; this is an alarmist page.

Trailers

Trailers are perhaps the safest way to take a very young child along. They are lower to the ground, so when you crash the baby will fall a shorter distance, even when you turn the trailer over. We would recommend that you do two things before using a trailer: ride in a trailer yourself for at least 10 miles, and take baby and seat to a pediatrician to ask if it is ok. Most parents have no idea how rough a ride it can be in a trailer. How hard can you jiggle your baby's brain without provoking "shaken baby syndrome?" Although trailer owners report good experience, how will you know instantly if your child is suffering harm back there? Probably they will cry, but can a baby whose brain is being bruised or neck is being overstressed communicate that quickly enough? While asleep? Trailer arrangements can be better if you wedge the child's head in on both sides so it cannot bobble around. But seated upright in a trailer the baby also needs a pillow behind them to provide clearance for their helmet in the back. Without the pillow their head is forced down by the back of the helmet.

Trailers with low-mounted hitches are generally less wobbly, but the wheels can snag on obstacles as you pass, and many trailers can turn over with surprising ease if one wheel rides up on something like a curb, or if you just have to take a turn too sharply. Any trailer can be turned over by hitting a bump too fast with one wheel -- ask the manufacturer. You might also want to ask if the trailer is constructed to protect the child in a rollover, which users report is a common occurance. How about protection for the child's bottom when you hit a rock that passes between the two wheels? ASTM is working on a trailer standard that will cover most of those points, but it is years from final publication.

Child Carriers

Child carriers are child seats mounted in front or in back of the adult rider. The front mounted ones let you look at the child while riding, and let you fall on the child when you crash. They balance better than the rear-mounted carriers, but many parents find that front-mounted seats also obstruct their riding.

At about the age of one year the neck development of some babies approaches the point where they can tolerate the weight of a helmet while awake. But a baby seated upright in a child carrier seat will go to sleep frequently. When that happens, the parent must stop and wait for the child to finish napping. Most parents don't have that much patience. It is common to see parents still riding, with the child's head lolling around with every bump and wobble of the bike. Ask your pediatrician: that is not healthy for the child! Again, the best advice we can give is take child and helmet to a pediatrician. They often give surprisingly good advice, and can take into account the stage of development your own child has reached.

Parents often have no idea how many jolts and shocks are delivered to the child's body in a normal, slow, careful bike ride. Rear-mounted child carriers are located directly over the rear axle of the bicycle. When you hit a one inch bump, the tire indents a little but essentially the wheel suddenly rises one inch, and the axle rises one inch, and the baby rises one inch. The bicycle saddle, on the other hand, is located well forward of the rear axle, so it rises much less than an inch. (If the abstract principles are not clear, think of a very long bicycle with a ten foot distance between the rear wheel and the saddle as the rear wheel rises one inch. The saddle will rise very little. Or better yet, you can measure the effect using a real bicycle ) In motion that makes the shock to a child carrier much sharper than it is at the saddle. In addition, the saddle is normally padded and partially suspended on rails that have some spring to them. And the rider normally compensates for bumps without it even registering by placing more weight on the pedals. Babies in child carriers can't do that. They take every jolt and jiggle.

Before you ride with a baby seat, check out this medical journal article. It has ten basic rules for using child seats. More than a third of the injuries to children in baby carriers occur when the bicycle falls over while standing still. Typically the bicycle is leaning against something, and the parent has put the child in the carrier, then turns to put on their own helmet, put the groceries in the panniers, unlock the chain, make an adjustment, put on sunglasses or something else normal. One wiggle and your child can be crashing to the pavement before your horrified eyes. On the road or trail, the same wiggle can send you careening into another rider coming the other way, or something even more solid like a car. With a child carrier your baby's weight is located entirely above the center of gravity of the bicycle, and the rear-mounted ones put the weight far back where it exerts extra leverage. Be sure your carrier meets the ASTM child carrier standard, since that requires means to prevent the child from getting fingers and toes in the spokes of the rear wheel.

Sidecars

We don't know much about sidecars, which seem to be a British specialty. They have been around in the UK for a long time. Some have elaborate protection from the elements. They probably affect basic bicycle handling more than the other commonly-used baby carriers, since they make your bicycle a tricycle and would affect cornering in strange ways. Consult a Brit if you are really interested.

Some More Cautions

The final question is what will happen when you crash. Certainly with your precious cargo you will be as careful as a bicycle rider can possibly be, and that will reduce the risk considerably, won't it? You will ride slowly, be extra alert for cars, be ready to swerve to avoid other riders, watch for bad pavement, compensate for side winds, watch out for overhanging tree limbs, avoid turns on patches of wet leaves, gravel, sand or ice, be careful in wet spots, test your brakes carefully before every ride, inflate your tires before every ride to the correct pressure and inspect them for nicks or sidewall bulges, inspect your bike periodically for cracks in the frame or any component, avoid rocks or other obstacles, watch out for dogs, warn roller bladers before passing them, deal with bees or other stinging insects, and ... did we miss some? Of course we did! There are 5,280 ways to fall in every mile, and if you ride long enough with your baby, you will too.

The normal risks of cycling, which are manageable under normal circumstances by normal careful riding and wearing a helmet, are considerably worse with the extra distraction and destabilizing weight of a child carrier and child, or even with a trailer. Nobody offers safety training for users of trailers or child seats, so you just gear up and ride. It is not enough to put a helmet on the child and blithely go riding. Even if the brain survives your crash, it seems unfair to subject a tiny body to that kind of trauma when the child might well have chosen not to ride if they had the intellect to consider the possible consequences. So the answer to the question "at what age is a child ready to be taken cycling" is "at the age when you are ready for the child to crash." And at the age when you are ready to explain injuries to the baby's grandparents or your neighbors, who will all think after a crash that you were crazy to take your baby on a bicycle.

If you are a hard core cyclist, nothing in the stuff above will likely deter you. And we may be just way too cautious, but that's your judgment to make, and we wanted you to know the downside, since you already know the upside to any family activity. We do hope you will wait until your child is at least one year old or robust enough to handle the bumps. And we would just repeat at the end the best advice to anyone considering taking a child on a bike: consult your pediatrician first. You owe that to the child.