Claymore Bike Fender


December 29, 2021

An overly dramatic bike accessory to encourage mud and followers to stay off your back.

Invention idea #03143.1 pulled from my notebooks to share.

Build it for fun & profit.

Explore the interactive blueprint.

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A quick search on the internet revealed these exist for truck hitches…

…but nothing for bicycles. Oooooo…untapped market!

My thought was to make more than just a “statement”, and add other functionality into it:

  • Fender
  • Reflector
  • Blinking tail light
  • Storage box

Of course you could go bananas and actually have a handlebar switch deploy something:

  • Marbles
  • Silly string
  • Water stream (super soaker in a claymore seems interesting)
  • Bubbles
  • Bees
  • Gray goo (sorry, more drama coming to the surface today)

I initially visualized putting it on the end of a fender or fender-rack. This would work if you want to use a better support system like they do with racks. Like this:

This is nice because attaching gear on the rack doesn’t obscure the claymore so it can do it's "job". But it's more costly to build. Alternatively, perhaps you can come up with a bracket to allow the claymore to mount to the back of the rack. 

The claymore idea is open in the motorcycle market too (I checked). Obviously, the attachment mechanism would be different. Unfortunately, I'm not sure the best mechanism since my motorcycle experiences are solely lived through Itchy Boots. :)

Proof of Concept & Manufacturing

Here's what I'd do to get to a proof of concept quickly:

  • Buy a claymore hitch cover (here or here has some).
  • Buy a bicycle fender that clamps to the seat post. Like this
  • If the clamp on the fender isn't right, buy a bicycle rack clamp of some sort that you can hack onto the claymore. Might be better to browse your local bike shop to find the perfect match.
  • Hack, mod, Dremel, epoxy, hot glue as needed to get something that works.

I'd test the market with a 3D printed version. It's a big print (8.5 x 3.24 x 1.375"), but printing's flexibility will let you experiment with different design features. There are claymore 3D models (and here) that you can leverage from to get started. Fender models too. Printing tips:

  • I wouldn't try to match the outer dimensions perfectly. Close is good enough as long as it looks good. I'd keep the dimensional relationship the same, just scale it down as small as possible. This will same time and money in manufacturing.
  • Use army green filament for authenticity. PLA is ok for prototype, final has to be in ABS or PETG. (Note: links are just examples. I have never purchased these brands so don't know their quality.)
  • The print should be a multi-part print to avoid issues. Raised lettering face should be printed with the letters facing up and glued onto housing
  • Housing is printed on it's side (for strength), in 2 parts and glued together.
  • Backing is printed separately and glued into place.

The claymore design lends itself naturally to mold injection where the mold is split in the middle. If you're doing a storage box design, then you'd split it between the cover and body. Pretty simple.

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