A shining example of engineering design collaboration

By collaborating closely, more than 10 UK-based engineering companies have developed a unique design of bicycle pedal that is greener and safer than alternatives on the market. Dean Palmer reports No less than 10 British engineering firms have collaborated over the last five years to develop a unique design of bicycle pedal that looks set to take the cycling world by storm. While the pedal itself is safer and more environmentally friendly (it is battery-less) than alternative designs, it's the engineered components inside the pedal that really caught Eureka's attention - the intricate gears, the miniature DC motor, the pulley system and spindle, hidden fasteners, the range of high performance polymers used, the injection moulding expertise required, the flashing LEDs and capacitor. The management of the project was also a challenge, with design input required from so many different engineering companies. Pulling this all together was the responsibility of Product Partners of Biggleswade, a design consultancy firm that deserves a big pat on the back, along with the inventors of the pedal of course, the technical director at Pedalite, Richard Hicks, and executive chairman of Pedalite, Chris Stimpson. Pedalite is a patent-protected, non-battery dependent bicycle pedal light with an integral, unique energy storage system. It incorporates three polymers for key components, all selected for their ability to withstand harsh use in extreme conditions. The pedal also won the Consumer Product Award 2005 at the Plastics Industry Awards in London in May. According to Chris Stimpson, Pedalite was developed to increase cyclist visibility in dark and adverse weather conditions. Unlike other lighting systems currently on the market, the device, once fitted, is automatically activated by the action of pedalling, rather like a dynamo but much more sophisticated and less energy consuming. Pedalite multiplies spindle rotation using a gearbox and generator (miniature DC motor) to convert rotational energy to electrical energy. This is sufficient to immediately energise the LEDs (three in each pedal) and charge a storage capacitor. Residual energy provided by the capacitor enables the LEDs to flash for up to 12 minutes, even when the cyclist is stationary or freewheeling. The pedal offers 360-degree conspicuity and a unique light signature; it flashes white to the front, red to the rear and amber to the side, therefore helping motorists judge the cyclist's distance and speed. Also, trials have shown that the LEDs produce beams of pulsed light that are clearly visible at 1,000 metres. So it definitely does what it says on the packaging. But the path to product launch was littered with ups and downs. Funding was provided on two separate occasions during the last seven years by the DTI. First, a Smart Award (worth around £45,000) followed by a more recent R&D grant worth around £55,000. Venture capitalist funding has also played a major part in keeping the company afloat so that it could continue to refine the design, produce prototypes and solve technical problems along the way. As Stimpson explained: "Our very first prototype was manufactured by a company called Ishida in Poole, a food handling and packaging company. We knew the MD at the company who was prepared to CNC machine a prototype for us, which would have cost us around £4,000. For a few hundred quid, we had an amazing prototype to show off." Five years ago, after securing more funding from Hertfordshire-based venture capitalist, Jeremy Cook, Stimpson and Hicks were able to begin approaching design consultancy firms with their prototype and presentation. The first consultancy approached was Cambridge Consultants, but this did not work out and so the pair went to see a smaller consultancy firm Product Partners based in Biggleswade. "It was a smaller, but hungrier company," explained Hicks. Hicks and Stimpson worked closely with Product Partners, who helped with the translation of the initial design right through to the final product. Product Partners also selected and co-ordinated the team of development partners for the product, including the toolmaker and injection moulder (ENL), the gearbox manufacturer (Davall Gears), the polymer distributor (Distrupol), the motor supplier (Trident Engineering) and the prototyping partner (Ogle Models & Prototypes). More than 10 engineering firms were involved at some stage of the project. Pedalite was finally launched at the UK Bike Show in April this year. As Hicks told Eureka: "The challenge was to find a way of providing cyclists with a lighting system that was automatic, integrated within the pedal and battery-free for today's environmentally-conscious world. In other words, if you got on your bike, you had lights, they were on all the time and you couldn't turn them off." Pedalite requires no batteries as the cyclist is the source of energy. A combination of super-bright LEDs, which are energised by a customised, miniature DC motor (supplied by Trident Engineering), produce six beams of light. Even at a pedal speed of 40rpm, energy is rapidly stored. "A cyclist will expend less than 0.5% (0.3W) of their propelling energy to energise a pair of Pedalites," said Hicks. At Pedalite's office in Kingston last month, the pedal was demonstrated to Eureka and disassembled for closer inspection. Hicks described the various components: "The generator is a miniature DC motor custom-made by Igarashi of Japan, but supplied through UK firm Trident Engineering. It has special, fine windings." The electronics and custom PCB came next. Pedalite worked closely with Analogical Systems of Wokingham, who developed and commercialised the printed circuit board (PCB). The capacitor is a bit special and was developed by Japanese company Nichicon and is ideal for very low voltage applications. It is an activated charcoal capacitor that has incredible surface area, offering 1,000 times better charge than an equivalent aluminium foil type, perfect for storing small amounts of energy from a cyclist. Hicks explained: "A cyclist pedals at around 30 to 40rpm which was not enough to energise the LEDs in each pedal. We needed 2V plus a little extra for charging the capacitor, around 2.3V in total." Prototyping on the project was critical. Another British company, Ogle Models and Prototypes, assisted here by developing a range of prototypes from early concept models through to fully working and illuminated prototypes, to support accurate product development. In order to verify the early designs, SLS (selective laser sintering) prototypes were made from 30% glass-filled nylon and fitted to a cycle for testing. Following successful trials of this model, the next step was to produce a set of SLA (stereolithographic) models. These were produced in 7570 water clear SLA resin, which was then given paint finishes to reflect the intended production finishes. David Bennion, marketing manager at Ogle told Eureka: "This accurate model was used to ensure that the generator, capacitor and the flashing LEDs would fit and work successfully. Using this finished SLA as a master, silicon moulds were produced and a number of vacuum cast parts were manufactured in PX223HT and Clearcast PU resins. Early models were then available for supplier understanding, customer presentation, marketing shots and other PR activity." Development of the Pedalite gearbox started around 16 months ago. The miniature 5: 1 ratio gearbox was designed and manufactured by Davall Gears (based on a conceptual design from Bill Bailey of Blue Print Technology). "Product Partners had a working envelope, Bill Bailey had a concept and Davall had to work it all out," quipped Hicks. The gearbox is designed to be activated at around 30rpm. So, if the cyclist pedals at 30rpm, the 5:1 ratio gearbox, in combination with the set of two pulley wheels (1.6 multiplier), give a total combined reduction ratio of 8:1. The rotor speed is therefore around 240rpm. The DC motor runs between 240rpm and 700rpm. The gearbox casing was manufactured by tool and mould maker ENL. It is made from polycarbonate as this is stable for the moulding process. The 5:1 gears inside the casing are also made from polycarbonate, DuPont's Delrin 100P (supplied through Distrupol) for its durability and very low coefficient of friction. The gears are PTFE-impregnated, so are self-lubricating. The integral pulley system was also manufactured by Davall Gears, but the spindle pulley, which retains the spindle within the housing, was moulded by ENL from DuPont's Delrin polymer. The belt for the pulley was sourced through Davall. According to Hicks, the complete gearbox/pulley system was developed from concept to final design in just four months. Fasteners also presented a design challenge to the team. The original design had inserts and screws located in the body of the pedal to hold the pedal body to the spindle shaft. It was eventually decided to hollow out each side of the polymer pedal body and use hidden (blind) fixings instead, which was more aesthetic. The pedal body is a complex one-piece moulding made from DuPont's Zytel. The two 'iglidur' integral bearings (supplied by Igus UK) are sealed using polyurethane seals, which lock in the grease and prevent the ingress of dirt and moisture to the internal parts of the pedal. The bearing supports are made from super tough Delrin, designed by Product Partners and moulded by ENL. Richard Gamble at ENL commented on the material selection for the pedal components: "We identified the need for Zytel glass-reinforced nylon for the pedal body because of the material's outstanding dimensional stability and impact resistance. Delrin 100 ST Super Tough acetal resin was selected for the pedal's internal bearing support and spindle pulley mouldings. Both components are subjected to high loading and Delrin was the obvious choice for this reason." Distrupol also played a critical role in the project by helping to solve specific design problems and performing mould flow analysis. As Hicks explained: "If the cyclist drops the bike to the ground on its side, we need to protect the optical lens of the pedal, where the flashing LEDs are located. So we needed a polyurethane that was abrasion resistant, optically clear and compatible with the housing material. After trial mouldings, Distrupol concluded that Pedalite could overmould polycarbonate with polyurethane. Distrupol also helped to minimise distortion during the moulding process." Testing of the final assembly was undertaken using a test rig developed by Tampoprint of Wokingham. This rig replicated the pedalling action of a 20 stone cyclist. After these tests, the only design change was in the radius of the spindle, which had to be increased slightly. While Pedalite looks destined for success in the cycling world, mainly because of its safety features, aesthetic design and environmentally-friendly credentials, the project is also a shining example of how multiple engineering companies can collaborate on a product design and translate this into commercial success. If you would like to purchase a pair of Pedalites for £50, go to www.pedalite.com or e-mail info@pedalite.com Pointers * The polymer gears and pulley system were manufactured by Davall Gears, the integral bearings by Igus * The generator is a fine-wound miniature DC motor, custom developed by Japanese company Igarashi, supplied through UK firm Trident Engineering * The Japanese-developed, activated charcoal capacitor has an incredible surface area offering 1,000 times better charge than an equivalent aluminium foil type, perfect for storing small amounts of energy from the cyclist EUREKA SAYS: This project reflects the strength and breadth of engineering design talent in the UK. From the mould maker and materials supplier through to the design consultant, more than 10 companies played their part in launching a groundbreaking product that will doubtless save many lives on our congested roads