The new SRAM DUB design means one crank fits many bottom brackets
If you're constantly feeling sad because the bike industry keeps inventing new standards, here's one that might make you feel a bit more cheerful. SRAM's just released a range of new cranks that'll work with all the major frame bottom bracket standards. Their new system is called DUB - or Durable Unifying Bottom bracket.
- Dear bike industry, what did we do to deserve Press Fit?
- Buyer's guide to waterproof shorts - keep your bottom dry this winter
- Review: Trek Roscoe 9 - a fun, fat tyred trail hardtail
The system claims to offer most of the benefits of oversize bottom bracket spindles with the bearing durability of conventional designs. As such, DUB cranks use a large diameter aluminium spindle that's slightly slimmer than 30mm designs at 28.99mm to allow for bigger and better bearing seals and cross-compatibility while being much lighter - and in some cases stiffer - than the conventional 24mm steel spindles of their GXP bottom bracket system.
The DUB cranks will be available across the entire SRAM range, with everything from XX1 Eagle cranks with lightweight carbon arms to less pocket heavy aluminium armed Stylo and Descendant models. Of course, you'll still have to get the right bottom bracket bearing to fit your frame, but at least this takes one half of the issue out of the equation.
SRAM is claiming some pretty impressive weight savings for their top end XX1 Eagle DUB setup. At 498g for a set of 175mm arms, 32T ring and bottom bracket, it's supposedly 78g lighter than a comparable setup with a GXP bottom bracket. It also compares favourably to Race Face's 518g Next SL G4 setup which uses a broadly similar design of oversize aluminium spindle paired to a special bottom bracket.
Interestingly enough, SRAM say that it's actually the bearing seal quality rather than ball bearing size that makes the biggest difference to the overall lifespan of your bottom bracket, but having just created a standard that uses relatively small bearings compared to old style BSA/GXP designs, they would, wouldn't they?
The DUB cranks will have bottom brackets that'll pair with pretty much every common standard out there, with brackets to fit everything save oddities such as Super Boost 158. There are chainrings available to fit regular or Boost chainlines in sizes from 30T up to 34T in all models, with X01 and XX1 Eagles adding a 36T and 38T option respectively. Even fatbikers will have a DUB crank to suit their broad bums, though there's no downhill specific design on sale at the moment.
So what are the downsides? As far as we can see, not much. While Press Fit bottom brackets still need to be pressed in, anyone with a threaded shell will need to get a slightly different bottom bracket tool to fit and remove cranks, like this Park BBT-79. As SRAM only do single ring cranks for their dirt groups these days, anyone out there wanting some multi-ring action is also left out. With DUB, the bearings that would have sat inside your frame on BB30 and PF30 frames will now also sit externally, though SRAM's claim of improved sealing should hopefully make that a moot point.
In the past, we have had issues with the steel bearing face chemically welding to aluminium axle on Race Face setups, requiring a hell of a lot of work to free them - think gear puller and blowtorch and you're about there - and we can't quite figure out from the release materials if there's anything that sits in between the axle and race to prevent this.
Anyway, we look forward to getting our hands on a DUB setup to put this to the test at some point soon.