This is the question people really mean when they ask me whether a bike is any good. Nobody wants to spend fifty quid and then worry every time their child rides off down the road.

So here is the honest answer, and then everything behind it.

Is a cheap bike less safe than an expensive one?

No. Price and safety are different things. What makes a bike safe is whether the frame is sound, whether the brakes stop it, and whether it fits the person riding it. An expensive bike with worn brake pads is more dangerous than a cheap one with good ones. Age and price tell you almost nothing on their own.

A bike is a simple machine. Almost everything on it can be put right, and the parts that wear out are the cheap ones. That is the whole reason second-hand bikes are worth buying.

What actually makes a bike unsafe?

Three things, in order.

A cracked or bent frame, which cannot be repaired and makes a bike dangerous at any price. Brakes that do not stop it, which is the most common real fault and also one of the cheapest to fix. A bike that is the wrong size, which is the one people never think of, and the reason a lot of children come off.

Everything else is maintenance. A rusty chain, soft tyres, gears that will not change, a wobbly saddle: all annoying, none of them dangerous on their own, and all of them cheap.

If you are looking at a bike and want to know how to check those three things, we have written about what to check before you buy. For children, size matters more than anything else on this page, and the right size is measured from the inside leg, not the age. If it is their first bike, weight is the next thing to look at.

What does the law say a bike must have?

Less than most people think, and not quite what they think either.

Required by law

A white light at the front. Lit between sunset and sunrise. Flashing is allowed.
A red light and a red reflector at the back. Both, not one or the other.
Two independent brakes. Front and rear, if the saddle sits 635mm or more above the ground. Below that, one is enough.
Amber reflectors on the pedals. Unless the bike was made before October 1985.

Not required, despite what people think

A helmet. The Highway Code says you should wear one. No law says you must, at any age.
A bell. Recommended, not required. New bikes must be sold with one; second-hand bikes are exempt.
A front reflector. Not on the list at all, though plenty of people think it is.
Anything at all in daylight. Lights and reflectors only have to be fitted between sunset and sunrise.

The rules in England, Scotland and Wales. Northern Ireland differs: a working bell is required there, and the pedal reflector date is different.

Three things worth knowing, because nearly everybody gets them wrong.

“Two brakes” is not a blanket rule. The requirement for two independent brakes applies where the saddle sits 635mm or more above the ground. Below that, which covers most small children’s bikes, one braking system is enough. The line is the saddle height, not the wheel size and not the rider’s age.

The lights rule runs sunset to sunrise, not “when it gets dark”. In daylight a bike does not legally need to have lights or reflectors fitted at all.

Flashing lights are legal. They have been since 2005, and there is still a lot online saying otherwise.

If you want to read the rules themselves, the brake requirements are in the Pedal Cycles (Construction and Use) Regulations 1983, and the Highway Code’s rules for cyclists cover lights, helmets and the rest in plainer English.

Do you have to wear a helmet?

No. There is no law in the UK requiring a cycle helmet, at any age. The Highway Code says you should wear one, and a “should” rule in the Highway Code is not an offence to break. It can still be raised in a civil claim if you are hurt, so it is not quite nothing.

My dad makes me wear one. That is a different kind of rule.

What rights do you have if something goes wrong?

This is the part that actually answers the question, and it has nothing to do with the price of the bike. It depends entirely on who you buy it from.

Buy from a business and the Consumer Rights Act 2015 applies. The bike has to be of satisfactory quality, which expressly includes being safe, judged against its description and its price. If it is not, you have 30 days to reject it and get your money back. Buy privately from a stranger and none of that applies. Private sales carry no such protection.

That is the real difference between a bike on a driveway and a bike from a business, and it is worth more than it sounds.

Two honest qualifications, because the law cuts both ways. A second-hand bike is judged as a second-hand bike: nobody can expect a used bike to be as good as new, and the price is part of the test. And if a fault is pointed out to you before you buy, or you would have seen it on a reasonable look over the bike, it is not covered. That is why every bike we list says what is wrong with it as well as what is right.

You can read section 9 of the Act if you want the exact wording.

How often do accidents actually happen because of the bike?

I wanted to give you a number here and I am not going to, because there is not an honest one.

The Department for Transport publishes the factors police record at cycling collisions, and there is no reliable figure for how often a mechanical fault was the cause. What its figures do show is that the factor recorded most often in serious cycling collisions is nobody seeing anybody: ineffective observation, and cyclists being hard to see. Equipment faults do not appear near the top.

Treat that carefully. The police record an opinion at the roadside, not the result of an investigation, and a bike that fails and tips somebody off on a quiet lane never gets recorded at all.

But the shape of it is clear enough. Being seen matters more than almost anything, which is why the lights are the bit of the law worth caring about.

The short version

Price and safety are not the same thing
The frame is the only fault that cannot be put right
Brakes, tyres, chains and cables are all cheap
A bike that does not fit is a bike that is unsafe
In daylight the law requires nothing. After sunset, lights and reflectors
No helmet law in the UK, at any age
Buying from a business gives you rights. Buying privately gives you none

If you want a bike somebody has already been through properly, that is what we do to every one we sell, and you can see what we have in and try it before you pay.

Are cheap second-hand bikes safe?