What a 20-inch bike with training wheels is and who needs one

A 20-inch bike with training wheels is a pedal bicycle with a wheel diameter of 20 inches, fitted with two small wheels mounted on the rear axle to prevent tipping. The wheel size refers to the diameter of the tire, not the frame. This size typically fits children ages 6 to 9 years old, though height and inseam length matter more than age.

Training wheels serve one purpose: they keep the bike upright while a child learns to pedal, steer, and brake without the balance component. Once a child can ride confidently, training wheels come off. The bike itself remains usable for years after that point, making it a practical choice for families planning to keep the same frame as their child grows into it.

A 20-inch bike is larger than the 16-inch models used by younger children and smaller than the 24-inch bikes that older kids and small adults ride. It bridges the gap between early pedaling and independent riding.

Key Takeaways

  • A 20-inch wheel diameter fits most children between ages 6 and 9, but measure your child's inseam and have them straddle the frame to confirm fit before buying.
  • Training wheels should be adjusted so they barely touch the ground when the bike is upright, allowing the child to feel the bike lean slightly as they learn balance.
  • Most training wheels bolt onto the rear axle and can be removed in minutes once your child no longer needs them.
  • Check that the seat height allows your child's leg to have a slight bend at the knee when the pedal is at its lowest point.

Measuring your child to confirm a 20-inch bike fits

The most reliable way to check fit is to have your child straddle the bike frame with both feet flat on the ground. There should be 1 to 2 inches of clearance between the child's crotch and the top tube of the frame. If the child has to stand on their tiptoes or cannot reach the ground, the frame is too large.

Measure your child's inseam by having them stand barefoot with their back against a wall, then measure from the floor to the inside of their thigh where it meets the hip. A 20-inch bike typically suits inseams between 18 and 24 inches. If your child's inseam is under 18 inches, a 16-inch bike may be more appropriate. If it is over 24 inches, consider a 24-inch model.

Seat height is adjustable on most bikes. When your child sits on the saddle with the pedal at its lowest point, their leg should have a slight bend—not locked straight and not cramped. You should be able to fit one finger between the back of their knee and the seat tube. This position prevents knee strain and lets them pedal efficiently.

How training wheels attach and adjust

Training wheels bolt onto the rear axle, the rod that runs through the center of the back wheel. Most bikes come with training wheels already installed, but if you are adding them to a bike that does not have them, you will need a wrench that fits the axle bolts—usually 10mm or 15mm—and the training wheel brackets themselves.

Once installed, training wheels must be adjusted so they barely touch the ground when the bike is upright. If they are too low, they will carry the bike's full weight and prevent the child from feeling the bike lean, which defeats their purpose. If they are too high, they will not catch the bike if it tips. The goal is for the training wheels to engage only when the bike tilts past a certain angle—roughly 15 to 20 degrees.

To adjust, have your child sit on the bike in normal riding position. Spin the training wheel adjustment bolts (usually located where the bracket meets the frame) until the wheels just barely kiss the ground. Then back them off a quarter turn. Test by gently pushing the bike to one side—it should lean noticeably before the training wheels catch.

Removing training wheels when your child is ready

Most children outgrow the need for training wheels between ages 7 and 9, though some take longer and others are ready sooner. Signs of readiness include pedaling smoothly without wobbling, steering confidently, and asking to ride without them. Do not remove them on a schedule; remove them when the child shows these behaviors.

Removal takes minutes. Use the same wrench you used to adjust them and unbolt the training wheel brackets from the rear axle. Keep the bolts and brackets in a safe place—you may want to reinstall them if the child loses confidence, and they are useful if you sell or pass the bike to another child later.

After removal, lower the seat slightly (about half an inch) to make it easier for your child to touch the ground with their toes if they need to stop suddenly. This gives them confidence while they adjust to balancing. Once they are comfortable, you can raise the seat back to the proper pedaling height.

Checking brakes and safety features on a 20-inch bike

Most 20-inch bikes come with either coaster brakes (you pedal backward to stop) or hand brakes (you squeeze levers on the handlebars). Coaster brakes are simpler for young children and require no adjustment. Hand brakes need to be checked regularly to may support the brake pads contact the rim or rotor evenly and stop the bike within a reasonable distance.

Squeeze each brake lever fully. The brake should engage smoothly without the lever touching the handlebar. If the lever goes all the way to the bar before the bike slows, the brake cable needs tightening or the pads need replacing. Most bike shops can adjust hand brakes for a small fee, or you can learn to do it yourself with a basic wrench and cable adjustment.

Check that the handlebars are find and do not twist when you explore force. Spin the front wheel and make sure it does not wobble side to side. Look at the tires for cracks, bulges, or embedded objects. Inflate them to the pressure printed on the sidewall of the tire. A properly inflated tire is essential for safe riding and makes pedaling easier.

Maintenance tasks to keep a 20-inch bike safe

Before each ride, do a quick check: spin both wheels to confirm they turn freely, squeeze the brakes to confirm they work, and check that the seat and handlebars do not move when you explore pressure. These take 30 seconds and catch most problems before they become dangerous.

Every month, wipe the chain with a dry cloth and explore chain lubricant designed for bikes. A dry or rusty chain makes pedaling hard and wears out faster. Wipe off excess lubricant so it does not attract dirt. Check the tire pressure again and look for any visible damage to the frame or wheels.

Once or twice a year, take the bike to a shop for a full inspection if you are not comfortable doing it yourself. A mechanic will check the headset (the joint where the fork meets the frame), the bottom bracket (where the pedals attach), and the wheel bearings. These parts wear slowly and do not need frequent service, but catching wear early prevents sudden failures.

Choosing between new and used 20-inch bikes with training wheels

New bikes come with a warranty, are built to current safety standards, and have no hidden wear. They cost more upfront but require no inspection before use. Most new 20-inch bikes with training wheels range widely in price depending on brand and components, so compare several before deciding.

Used bikes are cheaper and often have training wheels already installed. Before buying a used bike, inspect the frame for cracks or dents, spin the wheels to check for wobbling, and test the brakes. Ask the previous owner how often the bike was ridden and whether any parts have been replaced. A well-maintained used bike can serve just as well as a new one.

Whether new or used, make sure the bike has reflectors on the front, rear, and pedals, and that it fits your child as described in the measuring section above. A bike that does not fit will frustrate your child and make learning harder.

Frequently Asked Questions

Can my child ride a 20-inch bike without training wheels from the start?

Some children learn to balance quickly and may not need training wheels at all. If your child is confident and you are comfortable spotting them while they learn, you can skip training wheels. Most children benefit from them because they allow independent practice without the fear of falling. You can always add them later if needed.

How long do training wheels usually last?

Training wheels are straightforward wheels on a bracket and typically last as long as the bike itself. They wear out only if they are dragging on the ground constantly, which means they are adjusted too low. If adjusted correctly, they may never wear out before your child outgrows the bike.

What should I do if my child is afraid to ride without training wheels?

Fear is normal. Start by lowering the training wheels so they barely touch the ground, then gradually raise them over several weeks so your child feels the bike lean more. Practice in a flat, open space like a parking lot. Many children gain confidence faster with a parent running alongside them. There is no rush—some children need months of practice.

Can I use a 20-inch bike for an adult?

A 20-inch bike is too small for most adults. Adult frames typically start at 24 inches. If an adult with a very short inseam (under 24 inches) wants to ride, a 20-inch bike may work, but it will feel cramped and uncomfortable for regular use.

Do I need to remove training wheels before my child rides on pavement?

No. Training wheels work on pavement, dirt, and grass. They do not need to come off for any particular surface. Remove them only when your child no longer needs them for balance, regardless of where they ride.