A thin spacer or two are needed for running the DH Block with 9 or 11 speed cassettes, but to convert a 10 speed cassette only the Block itself is necessary. The DH Block is tall enough to help keep the chain from dropping into the spokes.

OneUp Components have announced another addition to their growing line of drivetrain accessories, this one aimed at downhillers looking to convert their cassette into a 7-speed setup. The DH Block is a lightweight aluminum spacer that replaces the three largest cogs on a SRAM or Shimano 10-speed mountain (11-36) cassette to make a 7-speed, DH specific set-up, and it's also compatible with 9-speed and Shimano's new XTR 11-speed cassette. Once the cassette is reduced to 7 speeds (or 6 with a 9 speed cassette), the whole span of gears can be quickly covered with just a couple clicks of the shifter, typically with a two tooth jump between each sprocket.Installation is about as easy as it gets – just remove the cassette, install the DH Block and any necessary spacers, then reinstall the cassette without the upper three cogs. On certain derailleurs it is necessary to set them up by clicking through the first two or three gears and then adjusting the cable tension, due to the fact that the limit screws don't have enough reach, but OneUp has a reference chart that details all of the compatibility options.The resulting gear range is the same spread as what's found on the road cassettes that many DH riders currently use, but without the one tooth jumps between each sprocket that can lead to excess shifting while trying to find the right gear. It's certainly a niche item, but it may be the ticket for riders looking for a less expensive alternative to SRAM's X01 DH cassette, or simply interested in trying a 7 or 6 speed drivetrain. In addition, the height of the spacer helps keep the chain from dropping off the backside of the cassette and into the spokes, potentially preventing costly wheel and derailleur repairs. Weight: 40 grams. Available in green or black, the DH Block retails for $45 USD.