I find the Box One derailleur slightly perplexing. I am not really clear about the purpose of the spring-loaded pivoting cable stop. It is satisfying to fiddle with - but... I am also not quite sure why the p-knuckle has a good 35mm between the contre of the p-pivot and the front parallelogram pivot. What does all that space do? And the styling of the outer parallelogram plate is interesting and attractive, but kind-of unnecessarily elaborate. A bit like a current model Lexus SUV. Bauhaus it ain't.

But overall, I quite like it. It is clearly not a Shimano product, and it certainly ignores all known SRAM styling cues. But most of all, it has the tell-tale signs of being the product of thorough, hard, work - rather than a pasty-faced, parasitical, low-effort, knock-off of someone else's proven best seller.

This is a 7-speed Down Hill version of the Box One, with a short pulley cage and (for some unknown reason) copious amounts of white paint. It's my favourite Box One.

• Derailleur brands: Box
• Country: USA, manufactured in Taiwan
• Date of introduction: 2017
• Date of this example: 2017?, the serial number starts B217...
• Model no.: BX-DR1-07ASC-BK
• Weight: 282g
• Maximum cog: 24 teeth (source: Box)
• Total capacity: 28 teeth? (a guess)
• Pulley centre to centre: 55mm
• Index compatibility: 7 speed
• Chain width: 3/32”
• Logic: top normal
• B pivot: sprung
• P pivot: sprung
• Materials: largely aluminium, with a composite p-knuckle