After cycling around the world, engineer-turned-entrepreneur Simon Evans came up with an invention which would change his life – his LittleBig bike ‘grows’ along with the child from age two to seven years


Ever since spending hours playing with my huge red pirate-chest full of Lego, I knew I would be an engineer. The best bit for me was always when you finished building the actual set, after which I would try and build something completely different with my new pieces. The creativity and problem-solving problem ability it gave me has carried forward into my design career, first in structural engineering and now as a bike designer.

After graduating with an engineering degree from Trinity College Dublin, I was offered an exciting structural engineering position in Cambridge. Working in this historic city gave me a unique opportunity to work on many prestigious projects including the University of Cambridge, the Royal Academy of Arts and the 16th-century manor house, Sawston Hall. These projects involved either sympathetic restoration of building elements, or carefully detailed new adjoining structures.

As good as the work was in Cambridge, I left my job in 2008 to follow my dream – to cycle around the world. My lifelong friend Fearghal O’Nuallain and I cycled unsupported through arid deserts and sweaty jungles, on dried-up salt lakes and over huge snowy mountain ranges. After 18 months – and covering over 30,000km in 30 countries in some of the hottest, highest, driest and remotest places on earth – we completed the first Irish circumnavigation of the globe by bicycle.

Coming home in 2010, I found myself in a very different Ireland to the one I had left in 2008. With the slowdown in the building sector, I found it difficult to get engineering work. Not wanting to emigrate, I got a temporary job in my local bicycle shop as a mechanic while I considered my options.

It was there that I came across pedal-less balance bikes, which allow children to develop their balance and motor skills much faster than the traditional method of using stabiliser wheels. However, as balance bikes are very small, kids grow out of them very quickly so parents soon need to upgrade to a bigger bike. This seemed wasteful and unnecessary, so I began thinking of designs for an adaptable kids’ bike.

I started with a simple two-in-one design where pedals could be added to a balance bike, but this had the same limited age-range as a balance bike, as it could not accommodate much growth (and kids grow very fast at that age!). If the frame was low enough to suit a small child, it did not have the ground clearance to attach the pedals and crank. Through my background in cycling, I knew that only a few adaptations would be needed to make a frame seem to ‘grow’, namely the saddle height and handlebar reach.

I came up with a few designs for making a ‘growing bike’ and each was assessed in terms of its amount of expansion, ease of conversion, build-ability and aesthetics. They were all modelled in 3D and AutoCAD to assess the best geometry and overall layout. Finally, I opted for the curved frame design with a rotating joint that we now have on the LittleBig.

Patenting the LittleBig bike design

LittleBig bikeBefore proceeding any further, I got a preliminary patent, which provides worldwide patent-pending status for one year. This gave me time to assess the market and develop the prototypes, while ensuring that my designs could not be copied by potential competitors. Being a ‘utility patent’, it is quite descriptive and covers the way that the bike adapts, in comparison to a ‘design patent’ that covers the look of something, such as the shape of the original contoured Coca-Cola bottle.

This design of the LittleBig involves using a two-part curved alloy frame joining the head-tube at the front of the bike to the seatpost and rear axle. The main joint is in front of the seat tube with the front tube overlapping the rear outer tube. A specially moulded cylindrical plastic shim between the tubes provides a snug fit and ensures the tubes can be rotated easily without binding.

To make the frame grow, the parent needs to remove the securing frame bolts, rotate the rear section 180 degrees then re-insert the frame bolts. The saddle then can be removed and inserted into the opposite (now-upper) end of the seat tube. This results in an increase in saddle height of 100mm and lengthens the handlebar reach by 50mm – which is enough to add two-to-three years onto the potential use life of the bike.

The pedals are attached with a simple alloy stub that protrudes from the bottom bracket and inserts into the underside of the frame when the bike is in the big mode. As there is provision for a clamp on both ends of the seat tube, the now redundant seat clamp from the little mode is used to clamp the pedal assembly along with an extra through bolt for alignment and safety.

The LittleBig provided some unique challenges because, unlike a normal bicycle, it has to work properly when in three different modes: little balance bike, big balance bike and big pedal bike. The curve of the frame (in elevation) has a dramatic effect on how much the bike grows; the smaller the bend radius, the more the bike arches upwards when the rear frame section is flipped. Similarly, since the seat tube flips along with the rear section, an optimum layout had to be found to give the best balance between saddle height and handlebar reach in the different modes.

With a preliminary frame design completed, a first stage prototype was built by Moto Engineering Fabricators in Dublin. This was to give an overall feel of how the bike would work and to judge if the proportions of the tubing were aesthetically pleasing. The next stage was to build a prototype with our chosen manufacturer in China to give a closer representation of the production models.

These pre-production models were fitted with our specified parts and tested in Ireland by children within the appropriate age range. Each child’s form on the bike was checked to determine what geometry changes were needed. After investing in the tooling used to form the precise shape of the LittleBig, and following two years of design and development, the LittleBig was put into production in autumn 2014.

About the LittleBig bike

The LittleBig begins as a pedal-less balance bike for children age two years and over. There is no need for stabilisers, as balance bikes allow kids to glide along effortlessly while quickly developing their co-ordination and motor skills. When the child has grown out of the small balance bike, the rear of the bike can be inverted, resulting in a bigger balance bike that accommodates for the child’s growth.

Ready to begin pedalling? Adding the separate pedal and crank attachment to the balance bike converts it into a proper pedal bicycle, which is suitable for children up to the age of seven years. The bikes are only available from

simon-evans-littlebigbikesSimon Evans is a structural engineer, round the world cyclist and bike designer. After receiving a degree in civil, structural and environmental engineering from Trinity College, Dublin, he worked as a consulting design engineer with Cameron Taylor in Cambridge. Evans was one half of Revolution Cycle, the two-person team that, in 2010, completed the first Irish circumnavigation of the globe by bicycle. Following a brief stint as a bike-shop mechanic and becoming a certified passive-house designer, Evans founded his business LittleBig bikes, having re-invented the kids bicycle. O'RiordanMechChina,Dublin,manufacturing
  Ever since spending hours playing with my huge red pirate-chest full of Lego, I knew I would be an engineer. The best bit for me was always when you finished building the actual set, after which I would try and build something completely different with my new pieces. The...