We have kept two KPIs from the previous iteration and developed three new ones based on user testing.
The gate of the carabiner should open when minimum external force is applied.
The mechanism should remove off the bolt readily.
The user should be able to remove the carabiner from the bolt quickly.
The user should be able to set up the device quickly.
The carabiner should not be cost prohibitive and not exceed the cost of a traditional carabiner.
The forced required to open the gate of the carabiner is 15N.
User is able to remove carabiner 5 times in a row.
User is able to remove the carabiner from the bolt in 30 seconds or less.
The user is able to set up the device in 1 minute.
The device can be removed from a bolt from a height of 25 feet.
There is a trade off between a detachable mechanism and a permanent design. The detachable mechanism is convenient because it can be used on any existing carabiner. The permanent design is more reliable and does not require additional assembly. After observing difficulty using an attachable mechanism for users, we decided that the permanent design is more appropriate.
There is a tradeoff between weight and durability. A more reinforced design may weigh more. Safety is a primary consideration, so that must be fulfilled before weight is minimized.
There is tradeoff between complexity of design and cost. Since the carabiner needs to be affordable, the device must be economical to manufacture and assemble.
The forced required to open the gate of the carabiner is 15N.
This indicator was measured using a force gauge and we found that the force required to open the gate is 8N. The average pulling force a human can exert is 200-400N, so this is an easily achievable amount of force for most people.
User is able to remove carabiner 5 times in a row.
This KPI passed during user testing. Users were able to remove the carabiner 5 times in a row after looking at the picture instructions.
User is able to remove the carabiner from the bolt in 30 seconds or less.
This KPI passed during user testing. Users were able to remove the carabiner in 5-10 seconds consistently.
The user is able to set up the device in 1 minute.
This KPI passed during user testing. Users were able to set up the device in less than 1 minute after looking at and understanding the picture instructions.
The device can be removed from a bolt from a height of 25 feet.
This KPI was tested on a climbing wall, and the device was removed from a carabiner 50 feet high.
We are confident in the current state of the design, although there are still areas for improvement. The design passed all of the KPIs and met all of the critical and secondary design criteria. Users were impressed with the device and reported that they could see themselves purchasing it for their own use.
We had many failures along the way and we progressed through many different concepts. In the end, we found that simpler is better and converged to a a functional prototype.
Moving forward, the device must be manufactured out of an industry-standard aluminum/zinc alloy to be usable on an actual climb. More so, concerns about safety and functionality in extreme situations must be addressed.
All in all, the design has the potential for broad appeal after further improvement and refinement.