By bike · Kids
Kids' bike parts matched by ISO size, because "20 inch" means two different rims.
Kids bike parts for 12, 14, 16, 20 and 24 inch wheels: tyres, tubes, complete wheels, coaster brake parts, 1/8 in chains and thread-on freewheels. A 20 inch kids bike wheel is ISO 406 most of the time, and 451 the rest. We read the sidewall number before we quote. Tyres from $22, tubes from $7, both indicative.
- 12 in · ISO 203
- 16 in · ISO 305
- 20 in · ISO 406
- 20 in · ISO 451
- 24 in · ISO 507
- 1/8 in chain
- Coaster brake arm
Sizing
Wheel size by age and inseam, with the ISO number that actually fits.
Age is a rough guide. Inseam is better: stand the child in socks against a wall, book between the legs, measure to the floor. Then read the small number on the tyre.
| Wheel | ISO bead seat | Typical age | Inseam | Usual brakes |
|---|---|---|---|---|
| 12 in | 203 | 2 to 4 | 35–45 cm | Coaster, or none on balance bikes |
| 14 in | 254 | 3 to 5 | 40–50 cm | Coaster, some hand brake |
| 16 in | 305 | 4 to 6 | 45–55 cm | Coaster plus front V-brake |
| 20 in | 406 or 451 | 6 to 9 | 55–65 cm | V-brakes, some disc |
| 24 in | 507 | 8 to 12 | 60–72 cm | V-brakes or disc |
Most kids' bikes sold as 20 inch roll on ISO 406. A few run 451. Read the sidewall. The small number is the one that matters. On a tyre marked 20x1.75 you'll find 47-406 somewhere nearby; on a narrower 20x1-1/8 it'll read 28-451. They are not interchangeable. A 451 tyre falls straight off a 406 rim, and a 406 tyre will not stretch onto a 451 rim at all.
Valve type is the second trap. Kids' rims are mostly drilled for Schrader, the same valve as a car tyre. Some lighter kids' bikes come drilled for Presta. A Presta tube in a Schrader hole rocks and tears at the valve base within weeks. A Schrader tube won't go through a Presta hole at all. Look at the valve before you order.
We do not quote a 20 inch tyre, tube or wheel without the ISO number from the sidewall or a clear photo of it. It's the single most common wrong order on kids' bikes.
Asked for most
What wears out on kids' bikes, and what we send.
Kids bike parts, 16 inch tyres and tubes
ISO 305. Tyres from $22, tubes from $7.
Driveway skids flatten a rear tyre faster than any adult commute. We match 16 in tyres by width, usually 1.75 to 2.125 in, and tubes by valve. A tube a size range too wide folds inside the tyre and pinches on the first kerb.
20 inch kids bike wheel, ISO 406
Wheels from $140 a pair, indicative.
Complete wheels are matched by ISO size, axle nut or quick release, hub spacing, and whether the rear hub is a coaster, a freewheel or a cassette. Coaster wheels need the brake arm and its frame clip. More on rims and spokes on the wheels page.
Coaster brake parts
Arm, strap, shoes. Quoted after a hub photo.
A coaster brake stops the bike when the child pedals backwards. The brake arm must be clipped to the chainstay; if the strap is missing, the arm rotates and the brake fails. That's the part we send most, and it's cheap. Worn internal shoes are a workshop job; we can supply them, but we'll tell you which hub first.
1/8 in chains
From $24 with master link.
Single-speed and coaster kids' bikes use a 1/8 in wide chain, wider than any derailleur chain. Do not fit a 3/32 in derailleur chain to a coaster cog: it rides up the teeth and throws. Length is set by axle position, so send the current link count or use the single-speed mode on the chain calculator.
Thread-on freewheels and V-brake pads
Freewheels from $35, pads from $12 a pair.
Geared 20 and 24 inch bikes often run a 6 or 7-speed thread-on freewheel, not a cassette. Pads for kids' V-brakes are threaded and short. Small hands mean short-reach levers; we can send those too, sized for the bar diameter.
Process
How a kids' bike inquiry runs.
Photograph the sidewall and the valve
Those two pictures settle the tyre and tube. Add the rear hub if the brakes are the problem.
We check ISO, valve, hub type
Every check is listed beside the part in the reply.
Reply within one business day
Target, Mon to Fri. Indicative prices held for seven days.
Confirm and we ship
Chains are length-checked against your numbers before they go.
Parents ask
Questions we hear from the driveway.
Should I fix the old bike or size up?
If the child's inseam has passed the top of the range in the table, size up. Don't spend $60 on parts for a bike that fits for three more months. We'll say so.
Can I remove the coaster brake?
Only by swapping the rear wheel, and only if the frame has rear brake bosses. Without them, the bike loses its rear brake. We won't supply a conversion for a frame without bosses.
Do you sell whole kids' bikes?
No. Parts only. That's the one thing this page isn't for.
Kids' bike inquiry
Send your bike's details.
The ISO number off the tyre, the valve type, and what's broken. We reply with the parts and the check run on each.
- Phone+1 (565) 555-2353
- Email[email protected]
- Desk68 Cedar Court, Office 12, Austin, Texas 28613