How to fit a childs bike seat

Children’s bicycle seats are a great way to transport your kids around, however they must be fitted securely. In this blog we’re going to look at which is the best style and how to fit a childs bike seat correctly to ensure they are safe and comfortable. 

Not all bikes are suitable to fit child seats. Carbon frames are designed to carry the rider but not a passenger.

Folding bikes don’t handle well with cargo. 

Full suspension bikes can’t accommodate rear mounted child seats. They are uncomfortable for the passenger because of the extra movement or stop the suspension handling properly because of the rear rack adding to the unsuspended weight. There are, however, some good front mounted seats for full sussers.

Front mounted seat

This type of seat is attached either to the quilled handlebar stem or the fork steerer tube.

• First check if your bike is big enough to comfortably ride with a front mounted seat.

• Stand over the top tube as close to the saddle as possible.

• Measure the distance between your belly and the stem. There should be at least a 22cm gap.

• If there’s less, you may struggle to get off the saddle when you stop. 

• Bikes that offer a more aerodynamic riding position, such as road bikes, might not be suitable for front mounted child seats because the rider needs to lean forward.

We have another blog post that discusses how to adjust bicycle stems before you begin fitting a front mounted child seat where you can find out how to adjust it for yourself. 

How to fit a childs bike seat on a quill stem

Be aware that there needs to be at least a 40mm gap between the top of the headset and the forward facing part of the stem so that the bracket can be fitted.

If the gap is smaller then, if possible, raise the stem. We have a video here if you’re not sure how to do this.

Don’t force it into place if there isn’t enough room.

• First measure the stem diameter.

• Now find the appropriate shims and fit them into the mounting bracket. If you’re not sure which ones to choose, check the manufacturer’s instructions.

• Look at your bracket and ascertain which is the top and which is the front.

• Clamp the bracket around the stem. Whilst holding the bracket with one hand, slide the bolts into position and tighten sequentially to ensure even tension, making sure that it is lined up with the front wheel. If you have a torque wrench, check the manual for the correct torque. If you don’t make sure it’s tight.

• Now slot the child seat into place.

How to fit a childs bike seat onto a threadless stem

• First measure the distance between the top of the headset and the forward facing part of the stem.

• If the gap is less than 20mm then you may not be able to fit a front mounted child seat. Don’t force the bracket into place if there isn’t enough room.

• Now find the appropriate shims and fit them in the mounting bracket. If you’re not sure which ones to choose, check the manufacturer’s instructions.

• Remove the handlebar stem. 

• Remove 20mm worth of spacers.

• Look at your bracket and ascertain which is the top and which is the front.

• Clamp the bracket around the steerer tube.

• Whilst holding the bracket with one hand, slide the bolts into position and screw sequentially. This ensures that the gaps are equidistant.  Don’t tighten them yet.

• Refit the handlebar stem and tighten the stem bolt. Align the stem with the front wheel and tighten the bolts on the side.

• Now, make sure that the bracket is lined up with the front wheel and tighten it, again sequentially for even tension. If you have a torque wrench check the manual for the correct torque. If you don’t, just make sure that they’re tight.

• When the bracket is secure, slide the seat into place.

Rear mounted seat

This type of seat is attached either to the seat tube (cantilevered) using a clamp or to the rack.

Cantilevered child seat

• This seat has two bars that slot into a clamp. This option offers a small degree of suspension as the bars spring slightly.

• Make sure there’s at least 7 centimetres gap between the bottom of the seat and the top of the tyre or mudguard. 

• Some smaller frames, or frames where the seat stays are attached low on the top tube, may not allow the clamp to fit high enough to achieve minimum clearance.

• There should be approximately 10 centimetres of clearance on the seat tube.

• With some step-through bikes the lower top tube means that the clamp can’t be fitted.

• If there is a gear cable running down the seat tube then check if the child seat clamp can accommodate the cable. If there’s no groove on it then fitting the mount will squeeze the outer casing and stop the cable inside moving which will affect front gear operation.

• Some frames have an offset gear cable stop. Only centrally fitted stops allow the mount to be fitted without squeezing the cable.

• Never fit the mount onto the seat post as the weight of a seat and passenger can bend or break the seat post.

• If you’re unable to fit a cantilevered child seat then the other option will be to fit a rear rack if your bike has mounts for it.
• Fitting a cantilevered child seat on a bike with a rear rack is not advisable as it will bang against the rack making a noise and causing discomfort for the little passenger when riding on uneven terrain. Use a dedicated rack mounted child seat instead. 

How to fit a childs bike seat- the cantilevered seat

• First select the front half of the mount.
• Work out which is the top and which is the bottom.

• Place the clamp on the seat tube. 

• Fit the bolts through the holes.

• Put the back part of the clamp in position. If you have a gear cable, make sure that it fits in the middle.

• If the holes on the back plate are threaded then screw the bolts into them, but don’t tighten fully. If not, attach the nuts onto the bolts and tighten but not fully.

• When you are happy with the position, start to tighten the bolts in a cross pattern to avoid uneven tension.

• If there is a cover, fit it over bolt heads.

• Now slot the seat into the mount.

Rack mounted seat

Check the weight limit etched on the rack. Many racks will take up to 25kg. If the maximum weight allowance is less than the maximum child seat allowance then consider fitting a different rack.

How to fit a rack mounted child seat

• Place the base onto the rack.

• Make sure that the four adjustable hooks fit around the edge of the rack.
• Tighten the two allen key bolts sequentially to avoid uneven tension.

• Check that the base is secure.

• Slide the seat into position.

• Now you know how to choose the correct seat for your bike and how to fit a child’s seat. I hope that riding with your kid on your bike will help to instil a love of cycling that will last for the rest of their lives.