May 2003

Carrying Children on Bikes - Trailer versus Kid Seat

New parents who want to cycle with their infant, toddler, or young child have two basic choices. A seat which attaches to the bike behind (usually) the rider, or a trailer which tows behind the bike.

This article is definitely colored by my opinion, which favors the trailer, and some of the safety issues below can sound scary. But ultimately, you have to like your choice, not me. If you feel better with one choice over another despite what I say, then by all means go with your gut. Both choices offer reasonable protection (when used with a helmet) and there's no point in buying something you won't use. Accidents are rare enough that you shouldn't let your fear prevent you from sharing cycling with your small child.


Psychologically, most parents react negatively to the trailer. It makes it feel like the child is more exposed, because they are farther away from you, "sticking out" into traffic. However most cyclists more familiar with the issues feel that the trailer is safer. I know of no studies that compare the safety issues, so we'll have to rely on anecdotal evidence, and my experience.

Parents typically worry about the worst-case scenario: "What if someone runs over the trailer?" This relates to the feeling that the trailer is more exposed. However consider this: what if someone runs over your bike? Is the child in a bike seat any better protected in this case? The answer isn't at all clear. The trailer may be more likely to be directly struck by the car in such an accident, but the seat is more exposed when your bike bounces away and into something else. In both cases, an impact from a car is likely to cause significant harm.

But so what, doesn't the trailer make an accident more likely, because you take up more space (or you're a bigger target, etc.)? As I said, I know of no statistics on this subject. But anecdotally, riders say that most cars give bikes with trailers a much wider margin when they pass, which would seem to indicate a lower risk of accidents. This also seems to indicate that trailers are more visible, not less.

However the worst-case scenario may not be the best standard. Minor accidents on bikes are much more common than the worst-case scenario. Worrying about that accident is much like worrying about a lightning strike. The largest chunk of bicycle accidents do not involve cars at all. Bike-bike, bike-pedestrian, and bike-road hazard accidents are all more common.

Simply falling over is an extremely common bike accident. Any well-designed trailer will stay upright if your bike falls over, whether moving or standing still. The bike seat on the other hand will fall with the bike, and your child will be falling to the ground from higher than they could ever stand (hopefully with a helmet on).

It should also be noted that child seats can be awkward without help. You have to load the child onto the bike before you get on yourself, at which point the bike becomes very unstable, and the odds of accidentally letting the bike fall go up sharply. If you have help, you should always be on the bike first, and let someone else load and unload the child to avoid this situation. If you are alone, hold onto the bike both at the handlebars and at the back. If you hold only one end, the bike can pivot at the handlebars and fall (yes, this can happen if you are holding just the handlebars).

Of course, if you do fall over while riding at speed there is the initial impact when you fall, but then you will slide on the pavement, and possibly slide into something hard. Arms and legs trapped under the bike can be very seriously scraped to the point of needing skin grafts in some cases. Even your face can be badly scraped as the helmet doesn't protect you there. On the other hand, a trailer completely surrounds the child, and straps them in place. Most of the time, the trailer will remain upright in such a case, and the child will be fully protected. If the trailer does tip, scrapes are still possible, but there won't be the weight of the bike (or the parent) on the child, and there will be a layer of fabric offering some protection. Depending on the harness, the cage may completely keep them from contacting the road.

If you slide into a hard object, there's no telling what might hit first. Bikes typically spin around somewhat while they slide. This exposes your child to the possibility of impacting first with whatever you slide into, with your momentum added to the impact if you are sliding with the bike. The cage of the trailer offers much better protection for impacts with hard objects.

Another very common accident is to flip over the handle bars due to over-zealous emergency braking, hitting something in front of you, or getting your front wheel trapped in a road obstacle (like a drainage grate with the slots oriented the wrong way). A child seat in a bike seat may reduce the tendency to flip just slightly, however a flip may still occur, and you will be flat on the pavement, with your bike following behind, upside-down. A trailer on the other hand sets the weight much farther back, and this leverage will almost certainly prevent the bike from completely flipping over. In any event, the trailer will not follow the bike over, and while it may get tumbled around, the child is strapped inside of a roll-cage frame (hopefully with a helmet on), and very well-protected. Also, note that there are child seats available that put the child on the handlebars. Those seats seem to be particularly at risk in these types of accidents, as the handlebars may hit the ground while you still have your weight behind the child.

Handling and Maneuverability

Both child seats and trailers can affect the handling and maneuverability of a bike. Handling here refers to your ability to control the bike, i.e. to keep it on track and keep it from swerving, to keep it from going somewhere that you don't want it to go. Maneuverability refers to your ability to go anywhere you like.

Trailers have a significant impact on maneuverability. The trailer is usually a bit wider than you are, so if you are used to riding through a tight space, you may want to be more careful -- you may not even fit at all. Likewise, you don't want to pass as closely to obstacles as you usually might. You won't be able to make a u-turn as easily. And you take up more length.

Trailers also have some impact on handling. Different trailers affect handling in different ways, depending on how they connect to the bike. I've found the bike handles a bit more sluggishly with a trailer.

Child seats cause a bigger impact on handling. That extra weight high up can make the bike feel a bit more unbalanced. The way it feels while turning, particularly at low speed, can be quite different. And when your child moves around, you can find that your bike wants to squirm around too, and suddenly you can find yourself drifting left or right. Child seats have a lesser impact on maneuverability. Your bike will pretty much fit anywhere that it could fit before. The only changes you find in maneuverability will be a result of the change in handling.


There are other day-to-day advantages and disadvantages of each choice.

Trailers off you additional storage space. They can generally carry up to 80 or 100 pounds, (most seats stop at 40-50 pounds) so you can use them longer, especially if your child grows faster than average. Most models can carry two children (at least one can carry three). Trailers also provide better shelter from wind, rain, and sun.

I hesitate to mention this because it is not recommended by any manufacturer (as far as I know), but some parents also choose to put car seats into the trailer (and I assume they find a secure way to strap the seat in place). This lets them use the trailer even for infants.

The seat's big advantage in utility is that it is on the bike. Once you park your bike, you are done. If you need to carry your bike up the stairs, you have a bit more weight, but that's it. If you need to go through narrow doorways, you still can. Another significant advantage is that since you are closer to your child, you can talk to them without yelling so loudly. And a possible advantage is that the seat is generally much less expensive, although this is not an advantage if you will get a trailer anyway when they outgrow the seat.

My Opinion

For almost any application, I recommend a trailer over a child seat. I suppose if most of your riding is in heavy traffic and you like to zip in and out between the cars, then a trailer won't work for you, but at this point, the primary safety issue is your riding choices, not the seat/trailer choice. If you simply don't have room to store the trailer, then use the seat.

I'm going to reiterate part of my introduction here. Ultimately, you have to like your choice, not me. If you can't get past your psychological discomfort with a trailer, and the child seat "feels" better to you, then by all means get the child seat. There's no point in buying something you won't use. And child seats do offer reasonable protection when used together with a helmet -- accidents are rare enough that you shouldn't let your fear prevent you from sharing cycling with your small child.

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  • Child Trailer Buyer's Guide
  • My Cycling Page
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