Even as the rest of the industry seems to be climbing an endless ladder to more gears, DH bikes are trending in the opposite direction. With the introduction of SRAM’s X01 DH, 7 speed became the new 10 or 11. The theory behind the smaller cluster is that bigger gears go unused on most DH race bikes that are actually being raced, and the 7 speed cassette provided better jumps between gears compared to cassettes designed for road bikes. Thanks to a narrower spread between the high and low gears, derailleurs with shorter cages and shorter chains can be used, all of which tend to improve shifting in abusive conditions.
For those who have decided fewer gears are for them but don’t want to plunk down a big chunk of change for X01, OneUp Components thinks they have a better way…
Called the DH Block, OneUp’s newest cassette adapter takes gears away rather than adding them. Essentially a giant spacer that sits between what’s left of the cassette and the hub, the DH Block is compatible with certain 9, 10, and 11 speed cassettes. When installed on a 9 speed SLX speed cassette, the DH Block ends up providing a 6 speed drivetrain while 10 and 11 speed cassettes get the full 7 year spread. Depending on the cassette used, gearing will range from 11-21 to 11-25t.
Just like the SRAM X01 DH cassette, when installed the DH Block provides an integrated spoke protector to keep you from chainsawing your wheel.
Depending on the derailleur used, you may have to follow the procedure outlined at the bottom of the chart. Since derailleurs other than Shimano DH and the SRAM X01 DH won’t allow you to set the low limit far enough in for the modified cassette, you must use the shifter to prevent overshifts. Before you attach the cable to the derailleur you shift 3 times which means that when the shifter is shifted to the 10th gear, it will be running on the 7th cog on the cassette. Once in the first gear, technically you will still be able to downshift but it will just slacken the cable and the derailleur won’t move. This is preferred over the alternate effect where having the additional shifts above the cassette would lead to over shifting and chain derailment.
Compatible with SRAM X01 DH derailleurs, the fact that you can convert a Shimano 10 speed cassette also means riders will have the option of running 7 speed Shimano Saint or Zee drivetrain as well. Both the SRAM X01 DH and Shimano DH derailleurs work perfectly with the modified cassette, and are able to be set up using the standard low limit adjustment. Weighing in at 40g, the DH Block is available in Green and Black, and will retail for $45.