The early years of riding are as much about inspiring confidence on the bike as they are about enjoyment. In fact, the two things are inextricably linked. So any bike with design features that can tick those boxes is worth considering. The best kids’ bikes can also accommodate growth and remove technical complexity for parents who might not be bike riders themselves. It’s not easy to tick all those boxes though, especially with one eye on keeping price down.
Ridgeback’s Dimension 20 definitely ticks a few of those, and inspired our test rider to try new routes and take on a few more challenges, all while keeping a smile on his face. He started riding this bike – which is aimed at 5.5 to 8.5-year-olds – as a six-year-old on the cusp of growing out of his 16-inch wheel bike. The size guide on the Ridgeback website suggests this Dimension 20 (there are five in the range) suits children from 111cm to 130cm. Which is, on average, around three years of growth.
In truth, the first couple of months of riding this bike it was clearly a bit big for him, but once he’d set eyes on it, there was no going back to his Woom 3 that had served him well until then. We put the saddle down as low as it would go and made sure his toes could touch the floor when straddling the saddle. It was a stretch, but as a confident rider, he made it work.
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A dropped top tube gives a little extra standover height
(Image credit: Future)
One key feature that allowed him to ride this size bike a little earlier than he would normally was the dropped top tube. It comes down from the headtube at a steeper angle before levelling off before it joins the seat tube under the saddle. This gives a little extra standover height when a rider is standing over their top tube, just in front of the saddle. If they can’t do that, they’re more likely to topple over sideways when they come to a stop.
Ridgeback has five 20-inch wheels in its range. The MX20 shares the same frame but comes with knobbly tyres and some cheaper componentry to drop the RRP by £60.
There’s another Dimension 20, which has a straight top tube for a slightly older age range (six to nine years) and comes in £70 dearer thanks to a slightly better quality frame (not that the rider would notice) and a better mix of components.
Finally, a second MX20 and the Harmony both have suspension forks, which we’d probably sway you away from. At this price (both are £349.99) the tech in the forks is unlikely to be up to much, and we’d argue that very few riders between the ages of six and nine would be able to tackle terrain that requires suspension.
A solid aluminium frame and wide, round tyres inspire confidence in young riders
(Image credit: Future)
This Dimension 20 provides adequate components with no unnecessary features that bump the price up. The weakest of the components was the aluminium V-brakes. They took a little while to set up and went out of alignment on a couple of occasions. This could have been down to knocks they received putting it in and taking it out of the car boot, but V-brakes were never the best (in my opinion), so do make sure they’re set up correctly.
Optimum set-up means having the right amount of cable pulled through to give tension, the brake pads toed in, and having them hit both sides of the rim at the same point in the pull. There was a tiny amount of reach adjustment in the brake levers themselves, although I would have liked them set a little closer to the bars.
The Jagwire cables and outers do mean the pull is smooth, and remained so throughout the test. The rims have a machined braking surface and a wear indicator – the black line running around the centre of the brake surface. Any child is going to grow out of this bike before they wear the rims down, but it’s a useful tool if you’re looking at a secondhand one.
The brakes worked as they needed to, they just need checking on regular occasions and adjusting when needed.
V-brakes can go out of alignment, so be sure to check in on them.
(Image credit: Future)
We loved the tyres on the bike, their nice wide, round profile inspired confidence, and the diamond tread with minimal raised profile worked well on all surfaces we covered. We’ve tested bikes with more aggressive treads (essentially knobbles that are raised a little higher and with bigger gaps in between them) but it’s rare to ride through mud wet and deep enough to need such a tread. These worked just fine.
Handlebar grips may not seem important, and you don’t need to spend extra money here, but as the main touchpoint for the rider they are essential. These had a nice, soft, rubbery feel, and there were no complaints from the rider that his hands hurt, or that they were slipping. The lip on the outer edge is there to keep hands from slipping off the side. The reach to the brake levers was 34mm (from the front of the grip to the back of the lever) with the adjuster screw wound in. Ideally, that would be a little closer to the bar.
The grips were nice and tactile, but the reach to the brake levers could come in a little.
(Image credit: Future)
The open drivetrain was a small step up from the 16 inch Woom 3, our previous test bike, which had a completely enclosed drivetrain, meaning no feet, ankles or fingers could get caught on the chain, spiked on the chainring, or covered in chain grease.
The Dimension has an exposed chain, but the chainring is covered on either side with a plastic guard, so ankles are protected from the teeth. A feature Ridgeback continue on their 24 and 27.5 inch wheel bikes.
The chain ring is covered on both sides to protect feet, ankles and fingers
(Image credit: Future)
Protection, for the bike, comes in the form of a cage around the rear derailleur. No parent will be surprised to read that a kid will happily lie their bike down (AKA drop it) in a flash to run to the toilet, stroke a dog, or pick up a stick that they like the look of.
Rear derailleurs are vulnerable when this happens, as the hanger they’re attached to can get bent with hard or regular impacts, hence the cage. Some other bikes come with a kickstand, which is a better option, but not all children will think to use it when they see a particularly special stick that they desperately want to take home.
A simple cage protects the rear derailleur from any knocks when the bike is left on it’s side
(Image credit: Future)
The Shimano derailleur gives a range of seven gears, controlled by paddle shifters underneath the right-hand brake lever. There’s a good chance this will be your child’s first geared bike, and learning when and how to use them is a key stage in their development.
Don’t be surprised if this takes a few months for them to build up the confidence to use it. The upwards shift into a smaller gear is actuated by pushing in the thumbshifter (away from your body), which has a little more resistance than some little hands can deal with. Changing down the sprockets into a bigger gear is done with the downshift paddle actuated by the rider pulling it toward them with their index finger.
This takes a fair bit of concentration at first, and means the rider is subtly adjusting their grip in order to change gear. Instinct tells me that this should be easier than a gripshift gear change mechanism, but my daughter picked that up quicker when she first moved to a geared bike. It’s hard to say if that’s down to the rider or the tech. I wouldn’t say one is more suitable for developing riders than the other; they’re just different.
Seven speed Shimano gear system is a mark of quality on a kids bike
(Image credit: Future)
Adjustment in the bike for a growing rider
The only adjustment on the Dimension 20 is in the seatpost that has 14cm of vertical movement. (For which you’ll need a 6mm hex key.) Growth spurts aside, this is likely to be more than enough to last at least two years’ of riding, hopefully a bit more. (The 5.5 – 8.5 year age range is a guide to the type of age the bike will fit, not a guarantee that your child will ride it between those ages. Kids vary wildly in their sizes at certain ages and grow at different rates.)
Sadly, there is less adjustment at the front of the bike. There is 22mm of spacers under that stem, so if dropped right down when you first purchase it (get a mechanic to do this if you’re not comfortable doing it) it can then be raised 22mm over time, along with the saddle.
There is however, no adjustment in forward reach with this fixed stem. This means that as the saddle goes up, the riding position will become a little lower and shorter, relative to saddle height. Without increased reach, a rider’s centre of gravity can go a little higher than is ideal. It’s not a massive problem, but it might just knock a few months of use off the bike. This can be countered by swapping out the stem for a longer one, just ensure it matches the fork column and bar diameters.
Any adjustment upfront will require a replacement stem
(Image credit: Future)
Value and Verdict
We’ve really enjoyed our time on the Dimension 20 which was a great transition bike for my six-year-old son as he stepped up to a 20 inch wheel bike for the first time. At £349.99 it’s quite an investment and it’s not hard to find other makes at less than half this price. But by spending more, you’re assured a good quality bike that, if looked after, will last the two to three years this bike should cover, growth-wise. There was nothing on this bike that let it down. The frame, Shimano gears and tyres really stood out, and the contact points are good too.
The brakes needed a little adjustment, but a cheaper bike would have even worse components needing even more adjustment. The lack of inbuilt adjustability at the front is a problem for growing kids, but can be tackled by replacing it with a longer riser stem. That’s a bit more cost both for the part and a mechanics time swapping it out, if you’re not confident, but would be worth it to get more use out of it.
Plus, if you do invest in a good quality bike, and look after it, there’s every chance of passing it down or selling it on when the time comes.
