Attaching the KoumKoum to the shoe of the users, in a comfortable and secure way, is much more challenging than would appear from a distance. For almost a year, we know that this is one of the most important aspects of the KoumKoum, and do research in this direction.
Why so important? Because a perfect, affordable, powerful and beautiful KoumKoum, that never breaks down and just delivers, would still be worthless if it flies off the feet of the users, or makes them feel uneasy when riding.
Software, motors, sprockets, chains, even the strength of the aluminium frame, all of this can be simulated on a computer. But straps, where they are, and how they interact with the shoe (and the person wearing the shoe), this cannot be simulated. Over the past months, we tried:
- Elastic straps that dont open. You put the KoumKoum like slippers. This works actually very badly and causes the KoumKoum to jiggle in use.
- Stronger elastic straps, closed with clips. Still too elastic and not secure enough.
- Fabric straps that close with a sliding mechanism like some belts have. They don't jiggle, but achieving proper tension is difficult. Putting this mechanism on takes quite some time.
- Shoe-like Velcro straps, so, a strap that goes in a buckle, then folds onto itself. Difficult to make work for a wide range of shoe sizes. A bit long to put on.
- Velcro straps without the buckle, so the right one simply goes over the left one (or vice versa). Super simple and elegant, but again difficult to tension well.
Finally, after consulting with many people and doing lots of research, we found a way that works:
At the front, velcro straps without a buckle but with a rubber mechanism of our design that allows to pull on the straps with two hands, achieving tension, and then strapping them down. At the back, a rubber heel retainer, on which are attached two more velcro straps, using the same rubber mechanism as in the front.
The complete strapping system achieves full retention and stability, with 3 points of contact with the shoe (front, in front of the heel, behind the heel). After an hour of use, nothing gets loose and the KoumKoum is still firmly attached to the shoe.
Assembly, so adding to straps to the aluminium frame, is also so easy that we will be able to offer user-replaceable straps of various sizes and color, for personallization!
This is very important for the feeling of being safe: the KoumKoum needs to feel like an extension of the user. As if the user's feet had wheels. Any play in the strapping mechanism breaks this feel.