Two more single-question calculators: stack and reach, handlebar width.

• Stack and reach calculator — enter the bike you ride with its stem and spacers, then the frame you're comparing, and it searches for the cockpit that puts your hands back where they are now. When nothing ordinary reaches, it says so and shows how far off the closest setup is; that's the frame telling you the size is wrong, not the stem.
• Handlebar width calculator — shoulder width in, a starting bar width out, centre to centre at the hoods. It notes the UCI racing minimum when your number lands under it, and explains the 25 mm gap between the two ways bars are measured.

Both run the same engine as the full tool, and each page explains its number: why stack is harder to fix than reach, and why bar width has drifted inside shoulder width.