When our children were small, taking the bicycles on holiday meant a roof rack, a stepladder borrowed from the garage and a good deal of hopeful lifting. Somebody always caught a knuckle on the gutter rail, and the fuel gauge dropped noticeably faster all the way to the coast. Nobody enjoyed the loading and nobody enjoyed the unloading either.
Towbar-mounted carriers have made that whole business a great deal easier, and grandchildren now arrive with bicycles that are heavier than anything we ever owned. This article covers what a towbar carrier asks of your car, why the lighting board matters in law as well as in practice, what the plug at the back of the car is doing, and the handful of checks worth making before you set off.
Why a towbar carrier suits a family so well
The appeal is simple enough. The bicycles sit at waist height rather than above your head, so loading them does not require a ladder or a strong back. They sit out of the airflow, which means less noise and a smaller effect on fuel or battery consumption than a roof rack. Most platform carriers also tilt away from the car, so the boot can still be opened without taking everything off first, which matters more than you would think when the picnic is at the bottom.
The trade-off is that the carrier sits directly behind the car, covering the number plate and the rear lights. That is where the rules come in, and where a little care saves a great deal of bother.
The lighting board is not optional
If a carrier obscures the car’s lights or number plate, it must carry its own. That means working indicators, brake lights, rear position lights, a rear fog lamp and reflectors, all of which are governed by the Road Vehicles Lighting Regulations 1989. It also means a number plate showing the same registration as the car, made to the proper British Standard rather than something printed at home.
None of this is difficult, because every reputable carrier comes with a lighting board and a plate holder built in. What causes trouble is assuming it will all still work after a winter in the garage. A board that spent six months on a damp concrete floor will often light up beautifully on the drive and then fail somewhere near Scotch Corner.
The plug at the back of the car
The lighting board takes its power from the towing socket, the same one a caravan or trailer uses. On most cars of the last fifteen years or so that is a single 13-pin socket. On older vehicles you may still find the two 7-pin sockets we grew up with, one black and one grey, and adapters are available to join the two arrangements together.
It is worth knowing that the socket does more than supply power. On many modern cars it also tells the vehicle that something is attached behind, which switches off the rear parking sensors and turns off the car’s own rear fog lamp. That only works when the wiring was fitted properly for that model. If you are having a towbar fitted or replaced, ask about the electrics as well as the bar itself, and if a garage is quoting for parts, an Erich Jaeger catalogue or a similar reference listing lets you check that the socket and wiring quoted are the correct ones for your car rather than a rough equivalent.
Weight matters more than people think
Every towbar has a limit for the downward weight it may carry at the ball, and the carrier counts towards it just as much as the bicycles do. A steel platform carrier can weigh fifteen to twenty kilograms on its own before a single bicycle goes on it. Two ordinary bicycles will then be comfortably within most limits.
Electric bicycles are another matter entirely. They commonly weigh twenty-five kilograms each, so two of them plus the carrier may already be at or beyond what the towbar is rated for. The figure you need is in the vehicle handbook and on the towbar’s own plate, and it is worth taking the batteries out and carrying them in the boot, which reduces the weight at the back and keeps them dry into the bargain.
What to check before you set off
A few minutes at the kerb prevents most of the problems people encounter on a long journey. The table below is the one I run through every time, and it has saved us more than once.
| What to check | Why it matters |
|---|---|
| All the lights on the board | Indicators, brake lights, side lights and the fog lamp must all work, and a helper standing behind the car will spot a failure in seconds |
| The number plate | It must show the same registration as the car and be clearly readable, otherwise you risk a fine |
| The weight on the towball | The carrier and the bikes together must stay within the limit set for your towbar, and electric bikes use that allowance quickly |
| The plug and socket | A damp or corroded connection is the most common cause of lights that work at home and fail on the motorway |
| The clamps and straps | Everything should be firm, with the wheels strapped and nothing resting against the paintwork |
It is the sort of check that feels unnecessary right up until the moment it is not. A brake light that has stopped working is invisible from the driver’s seat, and on a busy motorway that is the last thing you want behind you.
Looking after it between trips
Most carrier faults are simply the result of storage. Keep the board somewhere dry rather than on a garage floor, and let it drain and dry properly after a wet journey home before it goes away. Keep the cover on the car’s towing socket closed when nothing is plugged in, and look inside occasionally for the greenish deposits that mean corrosion has started. A small amount of proper electrical contact grease once a year is usually enough to prevent it.
Check the cable where it enters the plug rather than along its middle, because that is where the copper tends to break after repeated flexing. A fault that comes and goes as you drive is nearly always a cable or an earth rather than a bulb.
A calm few minutes at the kerb
Loading bicycles used to be the least pleasant part of any family holiday, and a towbar carrier has taken most of that away. What it asks in return is a little attention before you leave: lights working, plate readable, weight sensible, everything firm.
Do that and the bicycles will travel quietly behind you all the way to wherever you are going, which is exactly as it should be.
