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…


OneUp-Components-DH-Block-Green-Back OneUp-Components-DH-Block-Black-Back-Iso

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.

Click to enlarge.

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.


  1. wow, this makes about as much sense as adding a 42t cog and dropping the 11t. Can’t wait to throw my money away on a $45 cassette spacer.

  2. Is that just a SRAM PG cassette painted black for show purposes?

    This is a cool idea considering the bike I’m building would be a great candidate for one of these.

  3. @Scott B That’s actually a SRAM PG 1020, it’s an OEM cassette that’s either lightly painted or anodized black. I have one on my bike, and it’s already showing wear through to the metal underneath.

  4. What’s the point of adapting down to fewer gears if you aren’t using a wider chain/individual cogs? You aren’t gaining any of the fault tolerance/strength if you’re still using super narrow stuff. All you’re doing is giving yourself fewer options with no benefit… I guess you do get an ano spoke protector out of it!

  5. A couple things worth noting:

    @padrote – This product was designed primarily for 10-speed Shimano and SRAM X01 DH. In both cases the RD movement is controlled with the low limit screw (standard setup). Nothing hacky going on here.

    @ Nathan – Typical DH cassettes are 10-speed 11-25T road clusters. By using a mountain cassette/DH Block you get the same spread in fewer cogs. This offers better average chainline, better damage tolerance, less finicky setup and yes, a sweet ano spoke protector.

    @ ScottB – The cassette is a PG-1020

  6. @Jon- This really doesn’t provide ‘better damage tolerance’ or ‘less finicky setup’. An abbreviated cassette would be cool if you were putting it on a ss wide flange hub, but this setup adds nothing but a green ano pie plate.

  7. I thought cablepull for Shimano was non-linear. The cable pulled for gear 10 isn’t the same as gear 5, or whatever. Considering it isn’t big enough to be an effective dork disc, why not just use some leftover spacers, or put the full cassette on?

  8. @joes – Here’s a shot of product testing from Whistler Bike Park last season. You may recognize the rider…

    @greg – This product adds significant space between the spokes and the RD. Anyone who was experienced the disappointment of having a wheel eat their RD will appreciate it.

    Thanks for all the feedback.

  9. Does anyone here ride, or is it just B&M about something they’re not a candidate for anyway?

    Nice idea, more refined and durable than the ghetto setups of multiple plastic pie plates zip-tied, and keeps the small-jump road-gear spacing intact.

    Good work, and I look forward to seeing less failed ghetto setup debris on the trail.

  10. @Jon I get it and its ordered. I wanted to get the Ti Springs one last year to do a conversion with a 11-36 cassette but it is only made for a road block, so that conversion is a bit pointless and mainly for looks. Yours has got a point to it and looks good. On the Sram mech issue and setting it up with 3 click, Have you seen what Specialized are doing on the new Demo’s. They have got a similar 7sp set up. But instead of doing the 3 click trick they put a solder-less nipple style clamp around the exposed section of cable on the rear mech with a rubber doughnut ring about it to act as a stop so you don’t over shift. Its a good idea, but they probably would sue you if you copied it!!

  11. pdxfixed has one of the only logical comments here…

    I hate pie plates as much as the next guy, but for DH they make sense. Yes, blah blah blah….set your limits…properly tuned bleh bleh bleh…but DH takes a hell of a toll on a bike. Even with type 2, proper chain length, and limits perfect, shit still happens.
    For real though, if DH is solidly rocking the 7spd, why can’t they get 7spd specific FHB’s and a better dished out rear wheel?

  12. @BMW the same reason that FOX doesn’t make a DJ specific fork chassis: The market isn’t large enough for the big players to put that much R&D into it.

    adding some burl to an already existing product is fairly cheap, but manufacturing a whole new line of hubs & cassettes that aren’t compatible with anything else is a whole nother level.

    That said, the need is far less than it once was: there was a real reduction in durability from 7 to 8 speed, but 9 speed was probably a small improvement over 8, & 10 speed has probably almost caught up to 7: the chains are certainly higher quality than top quality 7s ever were.

  13. @bmw- they can. most of the high end hub mfgs produce ‘ss’ hubs with narrow freehubs that still accomodate 5-7 speeds, and allow for dishless builds with wide flange spacing, even on a 135/142 configuration.

  14. Jon. using a 10spd shifter with the cable pulled through three shifts that will still allow downshifting rates pretty high on my scale of hacky.

  15. your cage is probably still too long for DH (since we’re probably butchering a standard drivetrain) and three clicks of your shifter does nothing. I believe I’d rather have a 105 cassette since really all you are “gaining” from this is losing the use three cogs for the purposes of appearance. I guess.

  16. Just to clarify,

    – The setup is designed to use Saint, Zee or X01 RDs so DH cage length.
    – There aren’t three clicks on the shifter that do nothing in the standard setup.
    – You are gaining the full range of a 105 cassette in fewer shifts or an X01DH compatible cassette for 1/3 of the cost

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