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Bicycle Helmet Safety Institute

Trailbikes




Summary: Steve Grant's safety ideas and operating procedures for the kids' trailer-bikes that attach behind a parent's bike.




Note: Trail-A-Bike is a registered trademark, so we
have used the term trailbike as a generic equivalent.
Either way, it refers to a one-wheel child bike extension
complete with pedals added to the back of an adult's bike.



As our child has grown, we've recently switched from the trailer to a trailbike. This graduation conceals some very real changes in safety considerations. I realize that trailbike safety is getting some distance from your organization's focus on helmets, but it flows naturally from child carrier/trailer issues and is something I've not seen addressed elsewhere.

I'd start by suggesting children should not be carried on a trailbike until they've ridden, and fallen off, their own bicycle. Whether or not their own bike has training wheels, this will allow them to grasp the consequences of coming off.

Agree on a mount/dismount method with your child, so they never try to get on or off without you having control of the bike. Our child once dismounted in a most agile fashion with the bike still rolling along, and was told not to repeat the stunt.

Trailbikes are used only a short time during the transition from the trailer to a child's own bike. Thus, they are typically bought used. When buying a used one, they must be carefully inspected for proper operation. Both the ones I've been involved with came with safety issues. The trailbike should have a fender and must have a chain guard. In fact, I believe they should have european-style wheel guards. The hitch should be tight enough to keep the trailbike from swaying, but loose enough to pivot without binding. Either will destabilize the towing bike, with severe consequences in traffic or tight quarters. Loose hitches have to be replaced.

Kids like to experiment. On our first ride, our child got her runner caught between the frame and spokes of the trailbike. Fortunately we weren't going fast, and ground to a halt with the trailbike's wheel jammed and no injury. Later, she tried rubbing her runner against my bike's rear wheel. Then we noticed she was standing up, even while pedalling. (I guess she saw me standing up to pedal a lot of the time while towing her in the trailer!) The most astonishing discovery was finding her jacket, which she had been wearing, draped over the trailbike's handlebar! I was towing her, completely unaware she was removing it, and I don't even know how she did it.

Another parent reports that his sons repeatedly fell asleep on the trailbike! On the positive side, as descendants of tree-dwellers, probably our offspring have an innate reflex to grab small round things like branches or handlebars when they fall asleep. But you can't depend on it, and I hardly need to mention the importance of the child wearing a proper helmet, properly fitted, in case they fall asleep and fall off.

The safety flags supplied with the trailbike can themselves be a hazard due to the flimsy holders. Twice, with two different models, bumps have dislodged the flag, which then caught in the wheel. The towing bike should either have an extended rear fender, or the trailbike should have a bmx-style guard to keep debris from being thrown up into the child's face.

Most trailbikes attach to the towing bike using a seatpost clamp. Burley uses a specialized rear rack with a ball joint like a car's hitch. Both of these approaches have implications for braking. With the attachment point high above the ground, the weight of the trailbike during heavy braking will tend to lift the rear wheel of the towing bike, leaving the braking of all this weight to be done by the front wheel. This greatly destabilizes the towing bike, and lengthens stopping distances already increased by the additional weight.

Trailers with seatpost hitches have the same problem, which probably resulted in the adoption of the rear dropout hitches. Perhaps trailbike makers should follow suit.

Lastly, I'll talk about speed. trailbikes weigh about the same as trailers, but have less wind resistance and the child can contribute to propulsion. So speeds are higher than with a trailer. A bike towing a trailbike will coast downhill faster than a single bike. Speed builds easily and rapidly. But if you review some of the worrisome scenarios I've already mentioned, it would caution keeping the speed down while towing a trailbike. I've seen parents flying down steep hills with trailbikes, leaving me visualizing what would happen if, for instance, the child came off or they needed to stop suddenly.

Whether towing a trailer or a trailbike, the parent has to put themselves in the frame of mind of a semi-truck driver with a heavy, unstable and invaluable load.

Parents switching from trailer to trailbike will immediately notice how much kids move around on the trailbike. It seems like they never stop moving, and do not yet have any concept of balancing. All this unbalanced, random movement transfers to the towing bike, with the result that you will be continuously countering unexpected forces. To make it worse, the trailbike, most of which have only one gear, will always be out-of-synch with the towing bike as the child pedals, and this contributes additional destabilizing movement. A child who stands up to pedal will amplify this effect.

The result is that a bike towing a trailbike needs a lot of road space because of the resulting weaving. For instance, if the child decides to look around you on one side, and pedals down hard on the same side as you are just doing a pedal stroke on that side, the bike can veer before you know what's happening. This can easily result in going off the shoulder, or swerving in front of motor traffic. Though the trailbike is great because it's a step up for the child, you will sorely miss the stability of towing a trailer."

Steve Grant


Our page on trailers, trailbikes and child carriers.

Our page on taking a very young child along.


This page was last revised on: August 22, 2006.

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