Talk:Ceiling-mounted bicycle lift

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First Report

We received your report on the bicycle lift and were impressed with your work. Your analysis of the product is thorough, although in some places it would have helped to more clearly outline your conclusions and recommendations. Overall, your analysis seems to suggest that the product is pretty good as is. We were hoping that you would find more opportunities for improvement, but we will look forward to seeing your ideas in the next report. Detailed comments follow:

  • You stated that the most critical failure modes are caused by misuse and offer that “The best ways to reduce these risks are to emphasize proper use of the product and maintenance and tightening of fasteners in the user manual.” We are happy to hear your suggestions for redesign of our manual, but we don’t think this will be sufficient – in our experience, users don’t follow such directions, particularly for properly maintaining the product, no matter what we do, and we need to aim for an intuitive and foolproof design.
  • We couldn't agree with you more, to truly ensure the safety of the user, any improper use scenarios must be taken into account with the design of the product. However our suggestion for minor manual modifications is more for liability purposes, in case of some freak occurrence that realistically could not have been taken into account in the design of the product. With that being said, please refer to our updated FMEA for suggestions on how to further foolproof the design.


  • Your description of customer needs and pictures of the steps using the product are interesting (although I’m not sure why the person in the pictures appears to be making faces). Did you learn anything from studying these steps? A few questions that came to my mind are: What angle is needed with the rope to set the locking mechanism? Is it easy to pull the rope sufficiently to the side for locking even if the bike is mounted in a high location? Where do users typically install these? In your test studies with non-mechanically inclined users, was it easy for the users to figure out how to use the product without being instructed? Are there any opportunities here?
  • The locking angle (8 degrees) has been added to our updated FMEA summary. For more information about our market research and areas for oppurtunity, please refer to our second report.


  • The locking mechanism pictures are helpful, but a free body diagram and force analysis would help us a lot: I can’t tell from the pictures how it actually works. You noted in the FMEA that it is a major focus of attention for failure. Is it sized properly? What can we do to improve?
  • The locking mechanism capabilites are discussed in our structural analysis section, it's problems along with our suggestions for improving it's design our included in our updated FMEA summary.


  • Nice BOM with pictures and CAD models. How will the CAD models be helpful?
  • We recently updated our BOM summary to include a CAD assembly view of the product with all of it's components labeled for reference. We feel as though this will make reading our report much easier since any components we mention can be easily looked up in this new view to avoid any confusion.


  • We appreciate your thoughts on DFMA. You haven’t offered any suggestions for improvement - is your conclusion that we’ve already done everything we can? For your DFE you suggested use of recycled materials – do you think this is something we should look into?
  • After some more consideration, we recognize that the only material that you may want to consider using recycled material for is the cardboard box that the product is sold in. Please refer to our updated DFE section for further details.


  • Nice FMEA table – a lot of detail, but it’s not clear to us what you concluded. Our biggest concern is anything that might cause the bicycle to fall on someone – particularly a child. We have been involved in lawsuits before, and it’s important to us to make our product as safe as possible. How likely is it that our customers might install the lift improperly? You identified oxidation of fasteners that could cause bike to fall - this is a big concern – is this something we can avoid? I see you have latch failure as the top issue – this is big for us, and changing the manual will be good, but the product will often be used by people who did not buy the product or read the manual – we are looking to make the design intuitive and foolproof. How can we do this?
  • We have updated our FMEA summary to explicitly outline the areas that are reasonable causes for concern. We have provided several solutions to remedy these deficiencies along with our suggestions for what we believe is the best course of action.


  • Also, please include a free body diagram and numerical analysis of the input and output forces in your next report for the overall device and also for the locking mechanism.
  • We added a detailed structural analysis page to the report which take an in depth look at the load capacities of the critical components of the product. These results our summarized on our main page along with a conclusion of what we found from the analysis. The capability of the locking mechanism is also adressed in this section.


Additional Comments

It might be useful to know what mechanical advantage the pulleys provide, in order to determine what force the user needs to exert. Additionally, it might be nice if the preface to the Parts list on the front page said a bit more about the contents of the list, and some generalized information about the parts.

  • The mechanical advantage (4) has been added to our structural analysis section, and our parts list has been updated accordingly.

Revision

We received your response to our comments on the first report, and we are happy with the results. Your structural analysis is thorough, and the factors of safety are quite high. This is something we should consider in the redesign – can we save costs by reducing component bulk to a more modest factor of safety (say 4)?

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