Frog Bikes Fitting Guide

Sizing A Child, The Frog Way!

In contrast to many kids’ bikes, Frog bikes are sized by the 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.

At Summit Cycles we have bikes available in-store so we can check rider fit and offer further advice on sizing. Our staff are experienced in fitting Frog bikes and have access to the FrogFit App, where arm length, inside leg measurement and a rider’s confidence level together inform the model recommendation.


Average inside leg in cm (in) Approx age Wheel Size Frame Size
Tadpole Mini 24cm (9″) 1-2 10″
Tadpole 31cm (12″) 2-3 12″
Tadpole Plus 38cm (15″) 3-4 14″
Frog 40 40cm (16″) 3-4 14″ 9″
Frog 48 48cm (19″) 4-5 16″ 9.5″
Frog 52S 52cm (20″) 5-6 20″ 10″
Frog 52 52cm (20″) 5-6 20″ 10″
Frog 55 55cm (22″) 6-7 20″ 11″
Frog 62 62cm (24″) 8-10 24″ 12″
Frog 69 69cm (27″) 10-12 26″ 14″
Frog 73 73cm (29″) 12-14 26″ 16″
Frog 78  78cm (31″) 13+ 26″ 18″
Frog Road/Track 58 58cm (23″) 6-7 20″ 11″
Frog Road/Track 67 67cm (26″) 8-12 24″ 14″
Frog Road/Track 70 70cm (27″) 11-14 26″ 17″
Frog MTB 62 62cm (24″) 8-10 24″ 12.5″
Frog MTB 69  69cm (27″) 10-12 26″ 15″
Frog MTB 72  72cm (28″) 13+ 26″ 16″

PLEASE NOTE  We always recommend that you contact us at Summit Cycles where we can discuss your needs and find exactly the right fitting bike for your child. This guide is intended to help those looking to purchase with our Click&Collect service but we always recommend that you get in touch with us before ordering if you have any doubts about the size you need. If you purchase a Frog bike from us we will build it for you and ensure the fit and adjustment is right for your child. We recommend all bikes should always be built and checked by a qualified mechanic.