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(I did search, honest). It's a new through-axle of 28.99mm, the 1.01mm difference to BB30 means they have more space to seal the bearings properly - apparently small bearings are perfectly durable if the sealing is OK (it really took 30+ years of mtbs to work this out? Anyone remember ISIS?) and from the STW article:
"Aside from being able to produce a lighter and stiffer system, DUB was also developed to provide a more universal system that reduced the number of cranks and bottom brackets SRAM was offering – DUB will literally halve the number of stock units that SRAM has to offer"
LOL! A new standard that will replace the old ones
You couldn't make it up.
Yes.
Had to be done didn't it
Marketing aside, the DUB BBs are incredibly well sealed, and if you look at a RF 30mm BB (Or Hope) you do see why 30mm is probably just a touch to big (certainly for a BSA threaded shell) and 29mm does actually make sense.
SRAM and standards - an oxymoron if ever there was one! See the GXP BB thread for an example of another SRAM "standard"
you do see why 30mm is probably just a touch to big (certainly for a BSA threaded shell) and 29mm does actually make sense.
But the bearing sits outboard of the BSA BB shell, so can be as big as it needs?
Regular BB30 bearings could be as well sealed as the DUB ones?
Amusingly, I had a look at SRAM's website and was greeted with a popup asking me how likely I would be to recommend SRAM products to a friend and why.
My response contained a great deal of vitriol about new standard fatigue.
Had a look at these at a recent demo day - looks like a good idea to be fair. Just needed to come along about 10 years ago. And the BBs need to be Shimano prices otherwise I'll stick with Shimano.
[i]Have we done...[/i]?
Jan 2018. Probably a matching forum discussion, but good luck finding that 😉
But the bearing sits outboard of the BSA BB shell, so can be as big as it needs?
The issue is on the inside - the Axle fills the hole pretty much, leaving no room for a proper sleeve. Thats what does for Hope ones and why RF ones drag.
If you want to be granny ring compatible there is a limitation on the outside as well.
And we aren't allowed to use 24mm axles anymore because.....? :roll
You mean a sleeve between the axle and bearing, which then extends into a seal? (otherwise it shouldn't affect sealing?)
Yes preventing water and muck getting at a bearing will not affect its sealing. Other than to make it unnecessary.
ヽ(´ー｀)ノ
Ah, you mean an internal seal, spanning the cups ben?
The internal sleeve ... might not be that important but its one more thing that helps life. My point was that 30mm on a BSA threaded BB is not actually all that good. I am guessing its come down from PF30 and a desire to reuse that standard. If they'd made PF 30 actually PF29 in the first place everything would fit together with just that little extra room.
I can see it has some benefits over 30mm, I just don't see why that counts for anything- it's a criticism of a previous pointless standard rather than a defence of the new one.
The real question is, what does this offer that 24mm can't. And as with any standard, it's not just got to be better, it's got to be sufficiently better to justify the drawbacks of a change. And it isn't. Binning GXP for standard 24mm would be a worthy change that'd benefit customers massively but they've never felt a need to do that.
but if you're trying to make one standard that has a single axle, 24mm isnt so great as with things like BB30 you end up with either spacer cups or massive balls in your bearings to step them down to the 24mm. Probably the only axle size that really fits every weird BB standard going without lots of buggering about is something just shy of 30mm.
If you can ignore the normal marketing nonsense I'm not sure it all matters though, either you have Dub cranks or you don't, no-ones making you have them, and if you do from my experience and ones Ive seen in the field with much more miles on them than mine, you probably won't be needing another DUB bb any time soon.
BB30 can piss off too tbh.
Thing is, you say "nobody's making you" but that's not really true, individual bike buyers have essentially no buying power compared to OEMs, we've seen over and over that a pointless or unpopular standard can gain supremacy just because of market placement. This could easily be just yet another 15mm axle. And of course it couldn't be launched at the same time as boost.
What it definitely won't be, is one crank to replace them all, it'll either wither on the vine or it'll end up crowding the existing marketplace more.
TBH the very best thing that could possibly happen in the industry is the collective shoeing of marketing types and over-zealous product engineers who keep trotting out ridiculous and unnecessary new standards that we don't need. You only have to shoe a couple of them before the rest get the general gist.
I’m not sure it all matters though
With every new standard, retailers may feel they have to drop an old line.
Making stuff more difficult to get hold of.
Square taper/IIS/Octolink to HTII was a straightforward change/upgrade as HTII uses the same threads. The 24mm axle results from that.
To anyone with both a bike with 24mm axle and one with a 30mm axle, can you really tell the difference? Could you get on a bike without knowing and correctly say which was fitted? Stiffer? Just how much do you think a 24mm diameter steel tube less than 150mm long and fixed at two points close to the input force flexes?
The point of the above questions is that a lot (all?) of this is just marketing BS, the same as BB30 and the other press-fit bobbins.
Shimano's Dura Ace track crank is still Hollowtech cartridge BB - if there's one group of riders who you think would benefit from stiffer cranks, it's them.
We can thank Cannondale who bought Magic Motorcycle and their original BB30 design - except it was never designed for mass-manufacture and sloppy tolerances - they then tried to foist it on the rest of the bike industry for free. PF30 was just a fudge to address the failings of BB30.
The worst for me are RaceFace BSA30 - the weakest, pissiest design with weenie bearings that can't be easily cleaned or removed - even worse that the first GXP which would grind to a halt after one wet ride.
I'm actually OK with BB92/PF41 with 24mm spindles - I've had BBs last 5+ years and the wider BB shell does at least allow you to make a stiffer frame / bigger tyre clearances.
Judging by the box-full of BB tools I've got in my garage (there are now 4 different sizes of spanner need for external bearing BB cups FFS!) and I would say that only Wheels Manufacturing look to have got something that's suitable creak-proof and weathertight with the BB92 screw-together I installed the other day. Proper external seals too, not some flippin piece of hard plastic that cracks and breaks as soon as you try to remove it.
BB30 must measure more stiffly than 24mm, and my carbon FSA road cranks saved 250gm or so over their alloy equivalents