It finally happened - after talking about the next bike for 6 months, we finally got a new (to them) bike for our kid.
Why buy the next size up kids bike?
What is the next size up?
Our kid was riding a bike with 20" wheels, and we opted to go the next size up, which is a bike with 24" wheels. I've found that a bike with 20" wheels seems to work for most kids aged 6-9 or so. And 24" bikes work for most kids aged about 8-11. So there's some overlap around the 8-year-old mark. This all depends mostly on how tall your kid is and how long their legs are (their inseam is the critical measurement). Kids who are 8 and on the taller side might need to size up sooner. One of our friends' kids had to do this earlier than expected, because their 20" bike had a surprisingly short seat post, and they could not raise it any higher.
For reference, here are approximate age ranges vs tire sizes for kids bikes, in my experience:
- 14" bike: 2-4 years old
- 16" bike: 4-6 years old (our kid used one from age 5-6)
- 20" bike: 6-9 years old (our kid used one from age 6-8)
- 24" bike: 8-11 years old
- 26" bike: 10 years and older
Treat the above as general guidelines. This will depend a lot on how tall your kid is, how long their legs are, and how comfortable they are riding a bike. Kids who are more comfortable on the bike will probably need to have their seatpost higher so that their pedaling is more efficient. This comes at the expense of feeling comfortable at slow speeds or while stopped. They may need to use tiptoes to reach the ground if their seat is higher.
The range also depends on the bike itself. Some bikes have tubes that are more sloped and provide for a greater range of seat height adjustment. Or they will have longer seat posts so that a taller kid can still ride them.
Inseam and standover height
One way to understand which bike will fit your child is to measure their inseam - put a book between their legs, measure the height of the top of the book at their crotch - and then compare that to the standover height of the bike you are looking at. 99spokes has a lot of bike size data on their website, and you can also find numbers from the manufacturer's website. Once I found that our kid's inseam was about an inch higher than the standover height listed for a bike, I knew they'd fit.
Try a test ride
It also helped to test ride the next size up. We went to the Bay Area Bike Swap (which was amazing), where Woom had a bunch of bikes that we could try. My kid loved the Woom Now, which is a kids bike that has a front rack for carrying a backpack or other things. The kid fit on all of the 24" inch bikes that they had, so we were confident that they were ready for that size.
A friend also happened to purchase a 24" bike at that swap. Our kid tried it out and was able to zoom away on the bike immediately.
Better bikes generally go faster / farther
We are a car-free family and use our bikes for transportation. Sometimes it's tough to need to rush somewhere but still move at your child's pace. I suspected that a more performance-oriented next size up bike would be a little easier to ride than our current bike, and having a more efficient bike would make our commutes a little easier. I also think that there's less rolling friction with larger tires and wheels both at the tire and the road, and at the hub and chain.
Social pressures (from kids)
I did not want to give in to social pressures, but when our kid saw other kids in the same grade get new bikes, it was hard for them to not feel some envy. But there's also the next section...
Social and internal pressures (for adult)
New bike day is always fun, and it's especially fun for you and your kid if it's new bike day for your kid. I'd been looking for the next bike for a while, and I thought we were ready.
Buying the bike
We purchased the new (to us) bike from someone who had been selling it on Craigslist. The Craigslist marketplace is pretty robust in the Bay Area. Facebook marketplace is also sometimes a good place to find a new used bike. Be prepared to take it to a shop for a tune-up, or do some of the work yourself if you are able.
Our kid took the new 24" bike on a short test ride up and down the block and seemed to figure it out pretty quickly.
What was different about the new bike? What did our kid need to adjust?
Bike type differences - drop vs flat bars, different shifters/brakes
Their old bike had flat handlebars and trigger-shifting (which I had upgraded from a grip-shift, because I think it's hard for small hands to grip shift). The new bike had drop-style bars and integrated shifter/brake levers. I had to explain the 3 general hand positions for drop bars (tops, hoods, drops) and how to shift and brake. The new bike also has a front derailleur, which is a new thing to try out for the kid. I rarely use mine on my own bike, if it has one, and I don't expect my kid to use it too often either.
I had forgotten that smaller hands have less strength and reach, so braking was hard for my kid in the hoods. They chose to ride in the drops to be able to brake more easily. I had to make some adjustments to make braking easier. The old shifters on their bike accept shims to reduce the lever pull distance, and I made some (3D printers can be amazing) to reduce the pull distance.
Were there fit/size issues?
The new bike seems to fit okay. Our kid looks at home on a 20" bike, and they look a hair small for the 24" bike. The 24" bike has longer cranks, so the pedaling motion looks a little.. large.. but it doesn't seem to be too big of a problem. The standover doesn't seem to be too bad. It's a little high, and with the seatpost nearly all of the way down, my kid is on their tiptoes to balance when stopped. But we already had the seat post pretty high on their 20" bike and this was already the case.
Common used bike issues - this bike had them
The bike had been left outside for a while, so it had some obvious sun damage to plastic components, some rust on the steel parts, and spiderwebs here and there. Nothing too bad. The spiderwebs are easy to clean off. Nothing structural was damaged by the sun, though the shifter name plates were pretty busted and I replaced/made new ones.
There's a little bit of rust on the chain ring, but it's not too bad. I added some chain lube and the drivetrain felt pretty good.
The main issue was that the cables were old and probably had a good amount of internal corrosion. They will probably need replacement at some point not too long from now. The brakes were hard to pull due to friction, and the brakes were already a bit of an issue because of the small hands/hand strength/STI integrated brake lever issue mentioned above.
I removed the cable from the housing, lubricated it, and put it back in and the brakes were way easier to use. I should still replace the housing and cables in the future though.
Handling is different
Our kid switched from a mountain-style 20" bike to a 24" more road-oriented cyclocross type bike. The bike handles a little differently and our kid commented about how much harder it was to ride without hands on the handlebars, or to ride with one hand on the handlebars. I think the main reason is due to where their hands rest on the handlebars.
How has the new kids bike worked out overall?
It's way faster
For fun, I rode with the kid and asked them to sprint. I had to sprint to keep up. The new bike is way faster.
We haven't tried many hills yet, but will see how it performs on the way up and on the way back down.
My kid seems to really like the new bike. They still fit on the old one, so we are keeping it for the time-being so they have a choice of riding either. The older bike has wider tires, so if we do any off-road stuff, we'd probably take that bike. And it has fenders as well, so we'd take that bike if it rains.