Imagine a 50 mm sprocket on the rear wheel: That's the size of the chainring of a compact racing bike crank. But not on the crank, but on the cassette. So these are real cake plate dimensions that are now emblazoned on the rear wheel in terms of sprockets.

Here are the details: The US manufacturer One Up uses the XT 11-speed M8000 cassette in 11-42 gradation as the basis - and supplies an 18 and 50 sprocket as well as a longer rear derailleur cage. When attaching the sprockets to the body, the 50 t sprocket (available in green or gray) comes first and then all existing sprockets and spacers, only the existing 17 t and 19 t sprockets must be replaced with spacers and 18 t sprockets from One Up. This creates a cassette with a gradation of 11-13-15-18-21-24-28-32-37-42-50 with 19 percent more range.

The derailleur can also be converted; Shimano M9000 or M8000GS products are compatible for the conversion. For instructions on removing and installing the tuning derailleur arm, see here:

http://int.oneupcomponents.com/