Ah, but did you email On One saying " I need a 23 inch frame what have you got?" Or did you ask
"I'm 6'4" what would you recommend? " two very different questions to a company like On One.
As I said, measurements are irrelevant, it's the actual fitted and riding size that matters. Open your mind and ask the second question. The first question may be leading to a pit of despair. Grasshopper.
Don't just take my word for it though, see below from On One's Lurcher page
Sizing Guide
Rider HeightSuggested Frame Size
5'2"- 5'6" (157 - 167cm)X-Small (50)
5'5" - 5'8" (165 - 173cm)Small (52)
5′8″ to 6'0″ (173 -183cm)Medium (54)
5′11″ to 6′2″ (180 - 188cm)Large (56)
6′1″ to 6′5″ (185cm- 196cm)X-Large (58)
Sizing Notes
All frame size recommendations are approximate. A good fit will also depend on the correct choice of stem length, correct bike set-up for the rider and riding style.
Correct frame size choice can vary greatly with riders' torso length. If you have longer legs and a shorter torso, go for a slightly shorter stem. If you think you are borderline between sizes, and you have longer legs and a shorter torso, go for the smaller frame size. If you have shorter legs and a longer torso, go for the larger frame size to get the extra top tube length.
As the frame sizes increase, so does the length of the head tube. If you are inflexible or perhaps have a history of back problems, consider going for a larger frame size. This will increase the relative height of the handlebars making the position less “extreme”. The larger frame will also have a longer top tube, so you’ll need to compensate for this with a shorter stem.