A.S.S. Anti Strap System

So I thought I’d have a go at this blogging malarky. I can’t guarantee that the spelling or grammar will be correct or that it’s interesting but here’s my first attempt.


Top tube bags have become popular additions to bikes, especially since gravel bikes and bike packing enter the mainstream. They are particularly useful for quick access to food, money or a phone but the more we used them, the more we got frustrated by what we saw as solvable issues:

  1. Many bikes do not have bosses for bolt-on bags.
  2. The bags often want to rotate around the top tube, particular on more traditional round tubes.
  3. Straps rub paintwork and velcro holds water and mud.
  4. Headtube / steerer straps often clash with the stem position, particularly on bikes with a ‘slammed stem’.
  5. In order to stop large bags swaying side to side, the headtube strap needs to be done up tightly. This then pulls the bag into the stem bolts, wearing the bag and making it move when steering.
  6. Straps mean that the bag is slow to fit and take off meaning the contents need to be unloaded instead of taking the bag with you.

 

    We first looked at how could the bag be stabilised with using the headtube straps. Our idea was to create an attachment point for the straps that did not rotate with the stem. We 3D printed a prototype and set about testing it. It worked reasonably well, isolating the bag from stem movement, and it got a positive response when people saw it at Yorkshire True Grit ‘19. However, it still wasn’t easy enough to fit and our priorities changed so we parked the idea in order to concentrate on other projects.


         

    One of the many challenges was how to deal with attaching the clip to the bag when considering all the different strap types and location. The solution (see the 2 images on the right) was to use slot details to recreate the ‘ladder lock’ details from strap buckles so the straps of the bag lock to the clip regardless of the velcro location. The excess strap can then be trimmed and tidied with the rubber retainer.


    Inspiration to start again came from one of our own products - The Enduro Mount - the Enduro mount uses a flexible base combined with VHB (Very High Bond) tape to attach to a bike’s top tube - how good we use that principle to attach the bag to the bike’s top tube? The proof of concept worked well so the A.S.S. Slider was born, giving new impetus to sort out the front strap replacement. After 6 months, multiple design iterations, prototypes and tests later we were ready to launch the A.S.S system.

       

    Inspiration to start again came from one of our own products - The Enduro Mount - the Enduro mount uses a flexible base combined with VHB (Very High Bond) tape to attach to a bike’s top tube - how good we use that principle to attach the bag to the bike’s top tube? The proof of concept worked well so the A.S.S. Slider was born, giving new impetus to sort out the front strap replacement. After 6 months, multiple design iterations, prototypes and tests later we were ready to launch the A.S.S system.


    The Slider pieces need to slide together easily but when the bag is fitted it needs to be rock solid with no rattling. Many different tolerances, sprung clips and even a push-to-open lever were tested

     

    As well as eliminating straps the Anti Strap System means a bag can be fitted and removed fast.

     

    The production parts are produced in-house on a MJF (Multi Jet Fusion) machine using nylon and is finished by bead blasting. MJF is an industrial high volume additive manufacturing / 3D printing technology that produces parts that are as strong as injection moulding.


    The A.S.S. Anti Strap System removes the need for straps, even on bikes with no top tube bosses.

    More detail can be found here

     

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