Bike Sizing

Kids bike seat height

Set the saddle so a learning rider can put both feet flat on the ground while seated. Once they can start, stop and corner without thinking, raise it until the knee is just short of straight at the bottom of the pedal stroke. Those are two different heights and both are correct in their moment.

By Mike M.Published September 23, 2026Last updated September 23, 2026How we choose

The two positions

Learning height — feet flat

While a child is still learning to start, stop and balance, the saddle goes low enough that they can sit and plant both feet flat. They will use those feet constantly, and knowing the ground is there is most of what makes them willing to try.

This costs pedaling efficiency. That is fine. Nobody has ever quit cycling because their first month was inefficient; plenty have quit because they tipped over and could not catch themselves.

Riding height — a slight bend at the bottom

Once starting and stopping are automatic, raise the saddle so that with the pedal at its lowest point the leg is almost straight, with a small bend at the knee. At that height they can sit and reach the ground on tiptoe, not flat — and by then, they do not need flat.

Move between the two in half-inch steps, over weeks. A jump straight from learning height to riding height reads to a child as a different bike.

Minimum saddle height is the spec that matters

When you are shopping, the number to hunt for is the minimum saddle height, because it decides whether learning height is even available. A bike whose lowest saddle position is above your child's inseam can never be set to feet-flat.

Minimum saddle height, published, by model

Model	Wheel	Minimum saddle	Maximum saddle
woom GO 1	12"	10.2"	13.9"
Prevelo Alpha Zero	12"	10.9"	14"
Strider 12 Sport	12"	11"	17"
Prevelo Alpha One	14"	14.75"	25.2"
woom GO 2	14"	15.5"	19.3"
Prevelo Alpha Two	16"	16.9"	25.2"
Guardian 16 Original	16"	18.5"	23.5"
woom GO 3	16"	19"	25.1"
Prevelo Alpha Three	20"	21.2"	26.4"
woom GO 4	20"	22.4"	28.7"

Manufacturer-published figures, read 2026-09-23. Guardian publishes a minimum leg length rather than a saddle range for its 14 and 20 inch bikes, so those are not in this table.

Notice the 16-inch rows. Between the Prevelo Alpha Two and the woom GO 3 there is a 2.1 inch difference in minimum saddle height — on the same wheel size, for the same quoted age band.

The seat post check nobody does

Every seat post has a minimum-insertion mark etched near the bottom. If you raise the saddle past it, the post is no longer supported by enough frame and it can bend or snap. When your child needs the saddle above that mark, they have outgrown the bike — not the seat post.

Questions parents actually ask

01How high should a kids bike seat be?

For a learner, low enough to sit with both feet flat on the ground. For a confident rider, high enough that the knee is just short of straight at the bottom of the pedal stroke.

02Should my child's feet touch the ground on a bike?

While learning, yes — both feet flat. Once they can start and stop without thinking, tiptoes are fine and the extra saddle height makes pedaling far easier.

03How do I know if the seat post is too high?

Look for the minimum-insertion line etched near the bottom of the post. If raising the saddle would pull that line out of the frame, stop: the bike is outgrown.