Training wheels attach to the rear axle with two bolts and a bracket

Training wheels mount directly to the rear axle of the bike — the rod that runs through the center of the back wheel. Most sets come with a metal bracket that slides onto the axle from one side, then two bolts thread through the bracket and into the axle to hold everything in place. The wheels themselves sit on small arms that extend down from the bracket, positioned so they touch the ground when the bike is upright.

Before you start, check that your bike's rear axle has enough exposed length on at least one side. Some bikes have axle nuts that stick out too far, or the frame is designed in a way that blocks the bracket. If you can see at least half an inch of bare axle rod on one side, you have room to work.

Key Takeaways

  • Training wheels bolt onto the rear axle using a bracket that comes with the set, and you will need an adjustable wrench or the correct socket size to tighten the bolts.
  • The wheels should sit about half an inch above the ground when the bike is upright, so the child's weight stays mostly on the rear tire while learning.
  • Check that the training wheels are even — both should touch the ground at the same time — or the bike will pull to one side.
  • As the child gains balance, you can gradually raise the training wheels higher until they no longer touch, then remove them entirely.

What you need before you start

Gather an adjustable wrench (or a socket wrench if you know your axle bolt size), the training wheel set itself, and a flat surface where you can flip the bike upside down or use a bike stand. Most training wheel sets come with the bracket, two wheels, two bolts, and sometimes washers or spacers. Check the box to see what is included before you begin.

If the training wheels came with an instruction sheet, keep it nearby — different brands sometimes position the bracket slightly differently, and the sheet will show you which side of the axle to use. If you do not have instructions, the bracket typically goes on the side of the axle that faces the ground when the bike is upright, though some designs work on either side.

The step-by-step installation process

Start by flipping the bike upside down so the rear wheel is straightforward to reach, or use a bike stand to hold the frame steady. Locate the axle nut on one side of the rear wheel — it is a hexagonal nut that holds the wheel in place. You do not remove this nut; the training wheel bracket will sit next to it.

Slide the bracket onto the axle rod from the side that has more exposed length. The bracket should slide smoothly until it sits against the axle nut or the frame. Once it is in position, insert the two bolts through the bracket holes and thread them into the axle. Hand-tighten them first so the bracket stays in place, then use your wrench to tighten each bolt firmly — they should be snug enough that the bracket does not wiggle, but you do not need to force them.

Attach the training wheel arms to the bracket according to the instructions that came with your set. Most designs have the wheels already mounted on the arms; you straightforward bolt the arms to the bracket. Make sure both arms are attached at the same angle so the wheels sit level.

Adjusting the height so the bike balances correctly

Once the training wheels are attached, stand the bike upright on flat ground and check the height. The training wheels should touch the ground lightly — about half an inch of clearance between the ground and the rear tire. This means the child's weight stays mostly on the rear tire while the training wheels provide stability without fully supporting the bike.

If the training wheels are too low and touching firmly, the bike will feel stiff and hard to turn. If they are too high and barely touching, they will not prevent tipping. Adjust by loosening the bolts slightly and sliding the bracket up or down the axle, then retighten. Check the height again by rolling the bike forward a few inches — it should roll smoothly without the training wheels dragging.

Make sure both training wheels touch the ground at the same time. If one wheel is higher than the other, the bike will pull toward the lower side. Loosen the bolts and adjust the bracket until both wheels make contact evenly.

Common problems and how to fix them

If the bracket wobbles or moves side to side, the bolts are not tight enough. Use your wrench to tighten them again, checking that the bracket is still centered on the axle. If the bolts keep loosening over time, the bracket may be slightly bent or the axle may be damaged — try moving the bracket to a different position on the axle, or contact the bike manufacturer if the axle itself seems bent.

If the training wheels scrape the frame or the rear tire, the bracket is positioned too far to one side. Loosen the bolts and slide the bracket toward the center, then retighten. Some bikes have frames that do not leave enough room for training wheels on one side; if that is the case, try the other side of the axle.

If the training wheels do not spin freely, check that the wheel axles are not bent and that nothing is rubbing against them. Spin each wheel by hand to feel for resistance. If one wheel is stuck, it may need to be replaced.

Removing training wheels when your child is ready

As your child's balance improves, gradually raise the training wheels higher so they barely touch the ground. Over a few weeks, increase the height until the wheels no longer make contact at all. This lets the child practice balancing without the sudden shock of the wheels disappearing.

When you are ready to remove the training wheels completely, use your wrench to loosen and remove the two bolts, then slide the bracket off the axle. The bike will look and feel different without the extra weight, so let your child practice in a safe, open space before riding in traffic or on uneven ground.

Frequently Asked Questions

Can I put training wheels on any bike?

Most children's bikes work fine, but some have frames or axle designs that do not leave enough room. Check that your axle has at least half an inch of exposed rod on one side, and that the frame does not block the bracket from sitting flat against the axle. If neither side works, the bike may not be compatible.

Do training wheels come in different sizes?

Yes — training wheel sets are sized to match different wheel diameters, usually 12-inch, 16-inch, 20-inch, or 24-inch. Check your bike's rear wheel size (printed on the tire sidewall) and buy training wheels that match. Using the wrong size will position the wheels too high or too low.

How tight should the bolts be?

Tight enough that the bracket does not move or wiggle when you push on it, but not so tight that you strain the wrench or risk stripping the bolt threads. If you can move the bracket by hand, tighten more. If the bolt starts to feel like it might break, you have gone far enough.

What if the training wheels keep falling off?

This usually means the bolts are loose. Check them every few rides, especially after the first week. If they keep loosening, the bracket may be bent or the axle may be damaged. Try repositioning the bracket on the axle, or contact the bike manufacturer about replacing the axle.

Should I remove training wheels gradually or all at once?

Gradual removal works better for most children. Raise the wheels over several weeks until they no longer touch, so your child practices balancing without the sudden change. Some children are ready to have them removed all at once, but starting with the wheels raised gives them more confidence.