Clipless Pedal Adapters
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I love biking. Most of the time, when I’m on my road bike, I’m wearing cycling shoes with cleats that mate to my clipless pedals. While these are great for fitness rides, the pedals aren’t very useful when I’m wearing sneakers and using my bike to get around town. To get the best of both worlds I set out to 3D print platform pedals which would mount into my existing clipless pedals.

Not sneaker friendly

My starting point was an .stl model of my cleats which I found online. I then took this model and added a platform to it. In addition, I added heat-inserts and studs to increase traction.

To make sure each pedal would be strong enough, I created a static stress FEA using Fusion 360.

First, I established my load case by applying 180lbf to the top surface. This isn’t a true representation of how a foot would distribute the load on the pedal, but I first wanted to see if this design was even close to working. 

My initial attempts to run the model resulted in mesh failures which I suspect were caused by the geometry of the .stl that I used as my starting point. To work around this I modified my model by removing the .stl body and replacing it with a contact area where it was interfacing with the top portion of the pedal. I then placed a 3-dimensional fixed constraint on this surface.

The results of this model showed a maximum stress which was marginal at 1.3x yield. However, upon further inspection I found that these stress levels were only located in a few elements at the boundary of my contact area. This makes me suspect that the high stress values were just due to stress concentrations. Since the rest of the elements had high margins (>3x yield), and since this is a non-critical part, I was confident that this part would be unlikely to fail. 

I also checked deflection in the Z axis to see how much the pedal would flex. (Not much at all.)

The print came out successfully and seems to hold my body weight without an issue. 

One thing I will fix in the next revision is making the holes for the heat-inserts a little bit deeper since installing the them to their full depth caused a bit of oozing.

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