First, a little bit about me

Hello, my name is Steve Wood.

By day, I am a full time Design Engineer, I have designed for many years in the following industries, Automotive, Aerospace, Nuclear Fusion and now currently designing Bionic Arms for Open Bionics.

By night, I am a maker, breaker, fixer and tinkerer of all things going by the alias Gyrobot. I am passionate about Engineering. I am the director of Gyrobot Ltd.

I have knowledge of 3D printing and in particular with flexible materials, I have become a beta tester for an interesting range of materials and items for Recreus, suppliers of flexible filaments printing supplies.

I fell in love with the Engineering excellence that is the Brompton Bicycle for many years and I finally now own a Bolt Blue Brommie (electric) which I affectionately call the the “3B”.

Why the EZ Clamp Spring?

For 44 years (at the time of writing), Brompton have been creating these little marvels but one thing hasn’t really changed because it just works, and yet it is still invokes a little bit of frustration from the many.

That is the humble Hinge Clamp, this thing is one of the safety critical features of the Brompton, the last thing you want to fail and need to trust immensely. It needs to remain stiff over time and be used thousands of times. However, using it can be fiddly, not knowing when the clamp has released the frame, or having to align the plates so they don’t chip or edge the paintwork. Often, “speed folders” use a hand on each hinge and so they need a way of reliably aligning the plates single handed.

Sure, there are aftermarket solutions, which can replace the humble Hinge Clamp, but do you and should you trust them? Many great quality clamps are expensive, the low quality ones less so. Brompton take great pride in the quality of steel and materials they use in their components, it would be a shame to dismiss this and opt for something expensive and good quality or cheap and poor quality there are usually not many exceptions to this engineering rule.

Did you know that the Brompton Clamp Plate has a slight barrel shape to it, rather than being parallel sided like most aftermarkets ones? This is so that the plate clamps more on the corners of the hinge where the twisting stresses are higher :

Aftermarket on the Left (parallel sided) : Brompton original on the Right (Barrel sided)

Over time, the the ends of the C-Section will spread due to those twisting stresses of the frame. The Brompton Hinge will end up being more parallel sided but will still clamp sufficiently for longer. Whereas the parallel sided version can end up being an inverted barrel, i.e. slimmer in the middle and fatter at the edges), which may lead to it needing to be replaced sooner.

I wanted to create something that pushes the Clamp plates off the frame and allows them to be easily re-aligned without needing two hands or stopping the screwing process with one hand to realign again. Most importantly, I wanted to keep the original clamping components intact. It had to be something I had the tools to make too.

I hope you can appreciate this 1 gram widget for it’s paperclip simplicity and I hope it finally ends 44 years of that little bit of frustration.

Little bike + little widget = little easier.

Some Final Notes

I allow people to 3D print this for themselves, or for others for free (non-commercial). I have designed and gifted the CAD model freely for this purpose only.

The only authorised repository for this model is held on Thingiverse and it is licensed under the Creative Commons – Attribution – Non-Commercial – No Derivatives license. This design was published on 3rd of July 2020 and is established as prior art. Any subsequent patent application based on this or similar derivatives will be invalid.

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