...this is how ‘Cycling Claude’, a blogger for chain heroes, describes his first experience of riding the most compact folding bicycle in the world – the Kwiggle. He is not the only one with this opinion. Der Spiegel writes: ‘With a bit of practice, the bike can be converted into a handy package in just ten seconds.’
‘It works perfectly!’ eulogises manager-magazin.de. Die Welt says ‘folded cleverly.’ And Wirtschaftswoche’s headline was: ‘The smallest bicycle in the world comes from Hannover.’ Karsten Bettin developed the world’s most compact folding bicycle there. It is now in production: Made in Germany and Schubert & Salzer Feinguss is involved.
One of the key components is the steel folding hinge on the head tube, manufactured by Schubert & Salzer using the precision casting process. Its precision, durability and compactness meet the specifications for this compact world record.
The result is that mobility has been completely redesigned – between public transport and the office, between the train station and meetings, between the car park and the trade fair. And the Kwiggle turns the street into a catwalk – if you’re riding a Kwiggle, you’re bound to turn heads!
Its inventor, Karsten Bettin, considers his Kwiggle to be a unique combination of cycling efficiency, compactness and lightweight design. ‘We easily cycle 200 km a day on it with average speeds that no-one would expect. This is not down to our fitness, but due to the upright, highly anatomical cycling technique. For this unique combination of maximum compactness and a high level of endurance and rider comfort, the folding hinge on the steel handlebars above the head tube takes on a key role in our design, which has to withstand the highest load requirements.’
As a consequence, the most appropriate steel for the folding hinge was sought out in collaboration with material and casting specialists from Schubert & Salzer. ‘Schubert & Salzer’s suggestions regarding the quality of materials available, their composition, castability, corrosion behaviour and visual appearance were particularly helpful in this respect,’ says Bettin. ‘Of equal importance was the in-depth interaction relating to the optimal, casting-compatible component design and Schubert & Salzer’s flexibility as regards pushing the limits of the casting process.’
‘Schubert & Salzer produced samples to trial and optimise the design. The prompt delivery of prototypes was crucial for us in order to be able to carry out strength tests on the complete bicycle,’ says Bettin.
For this, we used our Voxeljet 3D printer. This enabled us to produce moulds for precision castings without the use of tools. This meant that the complete range of materials could be utilised efficiently down to the smallest quantities. The samples produced at the hands of experienced casters open up all the options without significantly impacting budgets. The cost of adaptations and optimisation of components is manageable. Bettin utilised this for the folding hinge, in order to implement small shape optimisations, which made the remaining assembly steps not only simpler but easier to replicate.
‘Alongside the optimisation in terms of the construction, the visual appearance and also the feel of the folding hinge is very important,’ says Bettin. ‘This folding hinge catches your eye immediately and is manoeuvred several times a day. That is why, alongside the functionality, we attach the highest importance to flawless surfaces. Many of our customers are experienced cyclists and use the Kwiggle for a new kind of mobility. With the level of quality that we have now attained we are able to compete with the top folding bicycle brands in the world. And that is also true for the folding hinge manufactured by Schubert & Salzer.’
‘For these sort of precision castings we naturally expect – regardless of the lot size – perfect dimensional accuracy across all elements, even from batch to batch,’ says Bettin. ‘We are now receiving parts in the range from Schubert & Salzer which also meet our high demands regarding tolerances.’
‘Our collaboration with Schubert & Salzer has been perfect for us in every respect. This has also been the case as regards the support from the sales representatives, who have handled our project in a professional manner. Contact has been maintained throughout the process, we are kept informed as regards delivery times and provided with technical insights concerning our project. At the same time, we feel that we have always been very well advised in technical aspects by the casting and material specialists. They have shared their extensive experience with us. This combination of know-how has been, and continues to be, a valuable help to us en route to series production.’
The results are already winning over bloggers from dasfahrradblog.blogspot.de, for example. They consider the Kwiggle to be ‘the ultimate compact bike’!