Sizing a child the Frog way!

In contrast to many kids' bikes, Frog bikes are sized by leg length rather than age, as this is the most reliable way of getting the right size of bike for each child. Age alone isn’t a reliable measure as there is a large spread of “normal” leg lengths & heights for each age.

We recommend taking the time to measure the rider’s inside leg - it’s easy to do:

  • Stand the child in socks against a wall

  • Place a small book between their legs, as high as is comfortable

  • Ask the child to move away and measure from the top of the book to the floor.

Once you have measured the inside leg, use the table below to find the right size of bike for your child. Please note we give the AVERAGE inside leg length for each bike, with the saddle at its lowest setting (please be aware there is tolerance on each side of this).

At this height, the child will safely and comfortably be able to get their feet on the ground. Don’t worry - Frog Bikes have long seat posts, so the saddle can be raised a long way as the rider grows.

Now you are ready to go to your local store who will have many of our bikes available so the rider can sit on a bike. You will get help and advice on sizing, receive on-going service, as well as support. Our stores have access to our FrogFit App, where arm length, inside leg measurement and a rider’s confidence level together inform the model recommendation.

Current ModelsMinimum Recommended
inside leg in cm (inches)
Maximum Recommended
inside leg in cm (inches)
Approx ageWheel SizeFrame Size
Tadpole Mini23cm (9")31cm (12")1-210"  
Tadpole31cm (12")38cm (15")2-312" 
Tadpole Plus36cm (14")44cm (17")3-414"
Frog 4036cm (14")43cm (17")3-414"9"
Frog 4440cm (16")51cm (20")4-516"9.5"
Frog 4743cm (17")54cm (21")4-618"9.5"
Frog 5350cm (20")62cm (24")5-720"11"
Frog 6257cm (22")65cm (26")8-1024"12"
Frog 6963cm (25")70cm (27")10-1226"14"
Frog 7367cm (26")76cm (30")12-1426"16"
Frog 78 72cm (28")83cm (33")13+ 26" 18" 
Frog City 5349cm (19")62cm (24")5-720"11"
Frog City 6157cm (22")70cm (27")8-1024"12"
Frog City 6763cm (25")76cm (30")10-1226" 14" 
Frog Road 58 / Track 5852cm (20")59cm (23")6-720"11"
Frog Road 67 / Track 6762cm (24")70cm (28")8-1224"14"
Frog Road / Track 7067cm (26")79cm (31")11-1426"17"
Frog MTB 6258cm (23")65cm (26")8-1024"12.5" 
Frog MTB 6963cm (25")70cm (28")10-1226"15"
Frog MTB 7266cm (26") 81cm (32") 13+ 26" 16"

Minimum Recommended
inside leg in cm (inches)
Maximum Recommended
inside leg in cm (inches)
Approx ageWheel SizeFrame Size
Frog 4339cm (15")50cm (20")3-414" 9.5" 
Frog 4843cm (17")53cm (21")4-616" 9.5" 
Frog 52 (Single speed)50cm (20")58cm (23")5-620"10"
Frog 52 (Hybrid)50cm (20")58cm (23")5-620"10"
Frog 5552cm (21")62cm (24")6-720"11"

PLEASE NOTE we always recommend that you buy your Frog bike from your local Frog store, who will build it for you and ensure the fit is right for your child. Our bikes should always be built and checked by a qualified mechanic.