I think you need to re-calibrate your expectations... I'm not saying this is a solved problem by any means, but I just tried this out with Claude Sonnet 3.5, and these instructions seem quite reasonable and detailed to me (about what I might expect if I spoke to a human expert and they tried to explain the steps to me over the telephone, for example). Does this mean this LLM is able to "reason"? I don't know that I would make THAT bold of a claim, but I think your example is not sufficient to demonstrate something that LLMs are fundamentally incapable of... in other words, the distance between "normal LLM statistical tricks" vs "reasoning" keeps getting smaller and smaller.
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My base prompt:
> Here is a hypothetical scenario, that I would like your help with: imagine you are trying to help a person create a bicycle frame, using their home workshop which includes a CNC machine, commonly available tools, a reasonable supply of raw metal and hardware, etc. Please provide a written set of instructions, that you would give to this person so that they can complete this task.
First answer: https://claude.site/artifacts/f8af03ba-3f2c-497d-b564-a19baf...
My follow-up, pressing for actual measurements:
> Can you suggest some standard options for bike geometry, assuming an average sized human male?
Answer including specific dimensions: https://claude.site/artifacts/2f5ea2f3-69d8-4a1b-a563-15d334...