Summary: Babies must be at least one year old before you try them in a bike trailer or seat. This page highlights what we believe to be the risks of taking your baby along. It discusses advantages of baby seats and trailers. There is an opposing view at the bottom.
Although crashes with an infant could be devastating, nobody expects to crash. But you do know that most bike trails and lanes are not smoothly paved, and shaking your baby is unavoidable. Here is a very informative quote from Dr. Tord Alden of Children's Memorial Hospital in Chicago, found on this BikePortland page:
"Neurodevelopment is critical during the younger years. An infant's brain is a bunch of neurons, uninsulated wires, if you will. During the first year the infant is developing the myelin sheath, which insulates the neurons and sets the stage for all the development and learning that the brain does next. If you had to pick a time when it is most important to protect the brain from excess vibration or bumps and jostling about it would be during that first year after birth."
For some other views, New York state law prohibits taking a child under one year on a bicycle, and most other state laws exclude them as well. The US Consumer Product Safety Commission thinks it is dangerous to take a child under one year on a bicycle, and here is their rationale:
Source: 16 CFR Part 1203 Safety Standard for Bicycle Helmets; Final Rule, page 11726
That 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 online postings by some parents who put their children in baby seats of one design or another and take them along on trailers starting as young as five 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.
For another official US Government view, we have excerpts from the Consumer Product Safety Commission's age-related guidelines for ride-on toys.
Assuming your child is over 12 months, there are some good choices for taking them along on bike rides.
But an alert reader of this page notes:
We would recommend that you do two things before using a trailer: ask your pediatrician if the child is ready. Then if you can find one that accommodates your weight and size, ride in a trailer yourself for at least 10 miles, at the speed you expect to travel. At least put a jar of milk in a trailer and ride as you will with the baby, checking the foam level when you stop.
Most parents have no idea how rough a ride it can be in a trailer. The wheels are directly under the passenger, so bumps are transmitted more directly: one inch rise in wheel = one inch rise in trailer. The same analysis applies to a child carrier that is located directly over the rear wheel of a bicycle. We have no idea how hard you can jiggle a baby's brain without provoking injury. Trailer owners report good experience, but it seems difficult to know if a child is suffering harm back there. They normally cry if stressed, but can a baby whose brain is being bruised or neck is being over stressed communicate that? While asleep? We often pass trailers whose occupants are crying, and always wonder: wet diaper, or shaken brain?
Another reader points out that lowering trailer tire pressure can reduce the small vibrations to the infant. Check the manufacturer's instructions for the lower end of the recommended tire pressure range. You could of course fit lower pressure tires if necessary as long as they are recommended for the trailer's rims and don't affect stability. Lower pressure usually means more rolling resistance.
Trailer arrangements can be better if you support the child's head on both sides with padding so it cannot bobble around too much, particularly when they doze off and you are not aware of it. But seated upright or reclining in a trailer the baby also needs a pillow behind them to provide clearance for their helmet in the back. Without the pillow their chin is forced down toward the chest by the thickness of the back of the helmet. Even if you use a child carrier that keeps the baby perfectly stable, the child will be subjected to a rougher ride than you will be on your bicycle, where your wheels are not directly under you.
Trailers with low-mounted hitches are generally more stable than the ones that attach to the seatpost, and most of them are made that way now. But they do turn over. Unless the wheels are shielded they can snag on obstacles as you pass. Any trailer can be turned over by hitting a bump or big pothole too fast with one wheel. Some of them turn over with surprising ease if one wheel rides up on something like a curb, or if you unexpectedly have to take a turn too sharply. The better brands test that on new designs to make sure they meet the requirements of the ASTM standard described below.
You might also want to make sure that the trailer is constructed to protect the child in a rollover, which some users report is a common occurrence for them. Does the trailer have protection for the child's bottom when a rock or obstacle passes between the two wheels? It can be tricky to avoid that. particularly if you are distracted by traffic or fail to see the obstacle in twilight. See below for a discussion of dirt and grit protection.
Steve Grant asked six trailer users with three different brands how often they had tipped their trailer over. Half had tipped, half had not. An interview with one mom revealed that her Chariot Cheetah had tipped over three times. Two were due to turning too sharp, to the right, at very low speed. The rear bike tire caught the tow bar with sufficient force to tip the trailer. (The back of the wheel is coming upward when it contacts the bar. Nubby mountain bike tires would increase the lift.) The third tip was due to going over a large rock with one of the trailer wheels. No harm done in any of the events. It is interesting that none of these turnovers was due to cornering too fast, but that can provoke a tipover too. One father who tows his kids to daycare every day says that when they turn over his kids laugh. He puts the trailer upright and they go on their way.
ASTM has published a trailer standard that covers some of those points. If you buy a new trailer, be sure it has a label stating that it meets the ASTM F-1975 bicycle trailer standard. The standard addresses rollover tendencies with a static test and a dynamic one where one wheel of the trailer is towed over an obstacle. A well-designed trailer and hitch will at least minimize the tendency to crash from those causes.
A reader who has a stable trailer and strongly disagrees with the above cautions on tipping and rough ride contributed this:
Your mileage will vary. Your trailer's design may be optimal, your riding style careful, the surfaces of the streets or trails may be very smooth, and your child may have a vibration-resistant brain. Nobody can judge any of that but you. Nobody has measured the risks scientifically, either. This page is just designed to give you an idea of the possible pitfalls.
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 usually goes to sleep frequently. When that happens, pediatricians usually advise that the parent must stop and wait for the child to finish napping. Most parents don't have that much patience, or may be unaware that the child is napping. 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 if that is healthy for the child. They give good advice, and can take into account the stage of development your own child has reached.
Parents sometimes 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 you are sitting on, 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 you sit on is normally padded and partially suspended on rails that have some spring to them. And the rider normally compensates for bumps automatically 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. In fact, their weight will dampen the shock you feel at the saddle.
Before you ride with a baby seat, you may want to check out this medical journal article. It can prepare you to avoid the most common hazards. 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 normal wiggle and the child can be crashing to the pavement. On the road or trail, the same wiggle might
send the bicycle careening into another rider coming the other way, or into something even more solid like a car. A
Japanese survey published in the Daily Yomiuri reported that 49 percent of injuries occurred when children fell
off their seats as bikes driven by their parents were being parked, 17 percent were injured when children fell off
bicycles while in motion, and 13 percent were hurt in collisions with cars, other bicycles or pedestrians.
A 2023 European study by Ptak et al tested a fall over with a 3-year-old dummy. They reached some very interesting conclusions. One of the authors is the founder of Cocoon Airbag Protection of Sweden, manufacturers of a system attempting to protect the child in the baby carrier. We saw a similar concept from a German manufacturer at Eurobike, but have not seen it on the market.
With a child carrier, a 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 destabilizing leverage. The ASTM child carrier standard requires the manufacturer to put a label on the carrier that says it will affect the stability of the bicycle. Be sure your carrier meets that ASTM child carrier standard, since it requires a shield to prevent the child from getting fingers and toes in the spokes of the rear wheel, and requires testing for fatigue resistance of the materials. And finally, this medical journal article has some sobering injury lists. Ask other parents, and you will find that many have used child carriers without problems, though. It's still your call.
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 and child carrier, or even with a trailer. Nobody offers safety training for users of trailers or child seats, so you just gear up and ride. We are not telling you to leave the child at home, but are suggesting that some thought is useful before you go.
The answer to the question "at what age is a child ready to be taken cycling" might be "at the age when you are ready for the child to crash if that should happen." And at the age when you are ready to explain injuries to the baby's grandparents or your non-bicycling neighbors, who will probably think after a crash that you were crazy to take your baby on a bicycle.
We may be just way too cautious, but as the parent, that is your judgment to make. We wanted you to know the down side, since you already appreciate so well the up side 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.
We would just repeat at the end the best advice to anyone considering taking an infant or toddler on a bike: take
child and helmet to your pediatrician first.
Tom Fine's page on why he prefers trailers.
A Consumer Reports page on riding with babies. Consumer Reports trailer buying advice.
Our page titled Why Can't I Find an Extra Small Helmet?.
Our page on child safety stuff with more links.
I wish that you would update your website so it is not so scary and making people feel that riding their bike with
their baby before 12 months is incompatible with responsible parenthood. Children are too cottonwooled in our
communities. We are so risk averse and actually the biggest problem is probably inactivity and rising obesity-The best
thing we can do for mums and children is encourage them to be active always. Bike riding is a relatively gentle activity
that mums can do with their babies and actually still get places and carry the baby and all their stuff (and even a
toddler or older child on a trailer bike as well). Do we really want mums to get out of the habit of riding for 12
months??? Your website might be safer from lawsuits if you are absolutely cautious, but this is not necessarily in the
community's best interests. You'll be more horrified to know that I also rode thousands of kilometres with my son on a
trailer bike and sometimes at 50km/hour-way over the recommended '15 km/hr' that the manufacturer was prepared to
confirm. He wore gloves and BMX protective pants most of the time. Yes we could have had a terrible accident, but life
has risks and we had wonderful adventures....and now he is easily the strongest bike rider in his school ......(although
he likes riding with his mates not mum anymore!!!). Your website needs more balance. Providing a link to an article
people have to pay for, 'that makes you wince' is not helpful. Incidentally, how much more bounced are babies that are
carried by their mothers in a sling all day compared to babies on bikes? Thanks for responding to my grizzles and it is
great that you have a website encouraging people to wear helmets.