All the experts we consulted cautioned against buying the cheapest bikes you could find at a big-box store. That’s because many of the mass-market discount bikes are of dubious quality, and the parts aren’t always easily adjustable. That matters because after that initial fitting with your child at a bike shop, you’ll want that store to refine all the touch points when you purchase a bike.
Those changes can include the reach to the bars, swapping out the saddle for one with a better fit, both width- and lengthwise, as well as adjusting seat height, and possibly the brakes and shifting components—all of which matter to the comfortable and safe operation of the bike. A cheap bike that doesn’t have common or adjustable parts will make it difficult, if not impossible, to change or swap these parts. So even if you chance into a bike that works for your kid right now, it won’t be able to grow with your child, and you’ll end up shopping for another one within a year or so.
A high-quality new bike will cost you $400 to $600. That is the rough range of a new kid’s bike that’s adjustable and lighter weight. But a good bike can also return at least part of its value on the resale market. Justin England is the director of business development at the Pro’s Closet, an online retailer that buys and resells bikes. He says big-box store bikes have “zero resale market. They go straight into a dumpster once your kid outgrows them.” But the flipside is that England says his company does resell bikes from well-known, reputable makers, such as Giant, Specialized, Woom, Cannondale, and Trek. England adds that a decent bike for a child will last through generations of kids because “you’ll sell it to a friend or resell it on Craigslist. That also means that it’s a sustainable product, as well as giving you a return on investment.”
That also means that you can save even more money by shopping the used market (more on that below), where a typical high-quality bike can go for $250 to $450.
Children aged 12 or 13 are ready for a small-framed adult mountain bike with 26in wheels. Many manufacturers make frames down to 14 or 15in, and some do 12 or 13in frames. Trials fans and serious off-road riders may want the smallest frame for the extra clearance over the top tube, but most teenagers can go straight to 14 or 15in.
Unless it’s specifically aimed at children, resist the temptation to put your nine- or 10-year-old on a 26in-wheel bike just because he or she happens to be able to reach the pedals. They will be better off on a 24in-wheel bike, which will probably be lighter and easier to control than an adult bike.
The smaller bike should also have more kid-friendly components, such as cranks, whereas even a bike aimed at small adults will typically have average-sized adult cranks (170 or 175mm). Younger teens would be better off on 150 or 160mm.
The bike industry has been dragging its feet on the issue of crank length for years. So if you want cranks that are the right length for your 13-year-old, you’ll probably have to have them shortened. It costs £50 from cycle engineering company Highpath.
An adult bike means adult prices: expect to pay from £400 for a sturdily built aluminium hardtail frame with a basic suspension fork. The closer you get to £500, the more likely it is the bike will have an adjustable suspension fork (for pre-load, at least), an 8-speed rear wheel (hence, 24 gears) and frame mounts for disc brakes. Some even come with cable disc brakes.
Don’t forget, though, that less is usually more when it comes to quality. Avoid full suspension entirely unless you’re spending a serious amount of money.
Remember, teenagers are acutely aware of peer pressure and will want a bike that’s considered cool. So, decide what kind of bike they want to ride.
Dan Joyce recommends Specialized’s Hardrock, which is available in both 12in and 15in frame sizes and has versions for boys and girls. The Saracen Mantra 1, is even burlier, which many teenagers will like, and is available in 15in. It comes with cable disc brakes too. Trek’s frames go down to 13in. The cheapest ‘proper’ mountain bike is probably Decathlon’s Rockrider 5. The XS size is 15in.
Any cheaper and you’re looking at street/towpath bikes. That’s fine, too, so long as you accept that below £300 you’re best off looking for a bike with no suspension, no disc brakes, fewer gears and no gimmicks. That is, ‘a bike’ rather than ‘an off-road bike’.
While adult cyclists may have several bikes, most children will at any given time have just one. The ride to school bike, the off-road bike, the bike for cycling in the lanes – they’re one and the same. No bike is best at everything so there will be compromises to make somewhere. Those may include balancing what your child wants with what your child actually needs.
This isn’t an issue with smaller bikes. A decent pavement bike will do everything its five-year-old owner will ask of it. As your child starts to use the bike for longer and different journeys – an issue for bikes with 24in and larger wheels, typically – the need for a bike that’s versatile enough to tackle all those different trips becomes greater.
A hybrid would be ideal, as the name suggests, but there are few – if any – made for children. The next best option is some kind of mountain bike, which your child will be happier with in any case because off-road bikes are more fashionable. Even those that won’t go off road can be good general-purpose bikes. The bike needs to be versatile. It’s a given that it will go off road, but are there eyelets to fit mudguards for weekday street use? Could you fit a rear carrier rack for a school bag, or for that cycling holiday?
This need for versatility will dictate some kind of hardtail – either with a suspension fork or a rigid fork. It’s worth changing the tyres, or at least getting an extra pair. Knobbly off-road tyres might look cool but they are slow and hard work on tarmac.
You could fit semi-slicks – tyres with some tread but not the tractor tyre knobblies of true off-road tyres. Your local bike shop may even be happy to swap them over at point of purchase. Semi-slicks will roll better on the road and will still be okay off road when it’s dry. A more effective option, but one that’s a bit more hassle, is to fit slick tyres to the bike for everyday use and then switch them for off-road tyres the night before singletrack excursions.
Size and weight need scaling down to suit a child. That sounds obvious but Cycling UK has tested tiny bikes for seven-year-olds that were heavier than adult ones. Bike weight is always a bigger proportion of a child’s bodyweight than an adult’s, often as much as a half or a third instead of around a seventh. That only makes it even more important to reduce it. Weight impacts on the fun and manoeuvrability of a child’s bike. Imagine strapping a couple of breeze blocks to your own bike. That’s the kind of extra weight we’re talking about, in relative terms, on some child’s bikes.
The trickle down of aluminium tubing into the lower price brackets means that many children’s bikes are finally getting lighter. While aluminium isn’t inherently better than steel, the way children’s bikes are built nowadays – cheaply, sturdily, with over-size and odd-shaped tubes – it’s a lot lighter. To check a bike’s weight before you buy, you don’t need to take a set of scales to the shop. Just pick the bike up. Then, with careful supervision, see how easily your child can lift it.
Standard cycle components are made to fit the average-sized man. Components for children’s bicycles clearly need shrinking down to suit a smaller rider. Frames and wheels always are, to some extent. With other components, it’s hit and miss.
In particular, cranks are almost always too long. Over-long cranks are ungainly and inefficient. They force the bottom bracket to be higher off the ground to avoid pedal strikes, and this makes it harder to get a foot down from the saddle. As a rule of thumb children need cranks that are roughly one-tenth their overall height, just like adults. So a child 1.2m tall needs 120mm cranks.
You can get a more accurate figure using 20% of leg length instead. To measure that, don’t use trouser size. Instead, subtract height when sitting against a wall from height standing against a wall. That’s your leg length. A fifth of this figure is the required crank length. The cranks don’t need to match to the exact millimetre but the measurement is a good guide. If in doubt, it’s better to err on the short side than long. The problem is that most manufacturers fit children’s bikes with, at best, whatever cranks ought to be on the next bike size up.
The handlebar should be narrower than the 60cm riser handlebar that you might use on a mountain bike, but this isn’t so critical. A wide handlebar is good for control and in a fairly upright riding position isn’t usually uncomfortable. If it is, you can easily cut the bar shorter with a hacksaw.
Brake levers must be within easy reach and the brakes must be easily operable: children have much weaker grip strength than adults. Check that you can reach and work each brake with one little finger. Hydraulic disc brakes are best, but generally cost too much to be fitted to anything but high-end children’s mountain bikes. Smoothly functioning V-brakes are OK. Grip shift-style twist shifters require less thumb strength than Rapidfire levers, and younger children in particular seem to find them more intuitive.
One measurement that doesn’t scale well to children’s bikes is reach – the distance between the saddle and the handlebars. Most children are happier in a riding position that’s both shorter and more upright than you would adopt, so they need the bars higher and closer. BMX handlebars are excellent on bikes with 20-inch or smaller wheels for that reason.
Optimum bike fit comes by progressing in stages, rather than fitting your child onto the biggest bike they can pedal. For safety’s sake, your child must be able to get a foot down easily when sitting on the saddle – both feet for learners – and able to stand with both feet flat on the floor while straddling the top tube in front of the saddle. Otherwise there’s an accident waiting to happen.
Children’s bikes can be divided by wheel diameter into five sizes: under 16 inches, 16 inches, 20 inches, 24 inches and 26 inches. These sizes correspond to approximate age ranges, but you might find your child is ready for (or outgrows) a given size a year or two earlier. Also, bear in mind that the use of different frame designs means that one manufacturer’s 24in-wheel bike might be slightly bigger or smaller than another’s.
You don’t have to buy your child a bike at every wheel size, although that would be ideal. Just be aware that a bike with significantly bigger wheels than those your child is used to will make the bike control harder. While a larger wheel will roll over bumps better, it will also be heavier and the steering will be less responsive. The reach to the bars will likely be greater and the bottom bracket will be higher.
Conversely, there will come a time when your child is just too big for that old bike. Two or three years per bike is fairly typical. You can recoup some of your costs by selling on a used bike, or you can extend its use by handing it down to a younger sibling.
Avoid the temptation to buy something cheap and nasty: a bike that barely gets used isn’t a bargain, however inexpensive it is.