SRAM DUB crank spindle standard- Mtbr.com
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  1. #1
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    SRAM DUB crank spindle standard

    Saw this pop up in my Facebook feed. SRAM has released a new crank spindle standard (different from their old 24mm and 30mm options) that comes with bb's for most frame shell standards.

    Looks like it simplifies things for SRAM from a manufacturing side, now that they can make just one spindle diameter instead of two. They also reference "other manufacturers" making cranks with one spindle diameter and selling bb fitments for nearly any frame. So it appears to be something they decided they needed to do on their own, also. At least for now, it looks like it will not be very feasible to mix SRAM DUB cranks with bb's from other manufacturers, but I suspect companies like Wheels Mfg will be releasing compatible bb options before too long.

    This video seems to have more info than any text on the website, but it's heavy on the marketing and very light on details.



    One interesting thing is that it appears as though this is available for pretty much all of SRAM's mtb cranks, and every crank model looks to be available with multiple spindle lengths. One thing that's not clear is whether the spindles are modular and can be switched like RF CINCH, FSA, and other modular cranksets. Maybe the spindle lengths will be set from the factory, but that method seems more expensive to me to make than offering a modular setup.

    https://www.sram.com/sram/mountain/d...rxvd13am6d747g

  2. #2
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    I saw this and I can't really understand why 28.99?!?! I think we were just living with 24, 24/22 and 30 for too long now!

  3. #3
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    Interesting concept. Hopefully it truly simplifies the crank/BB game.

    Biggest takeaway from the video, prior to applying for a job at SRAM one should grow a mustache. Maybe even put a picture of you with said mustache in your resume or additional documents.

  4. #4
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    Quote Originally Posted by mfa81 View Post
    I saw this and I can't really understand why 28.99?!?!
    Because they want to sell you a bottom bracket, rather than having you use your existing 30mm RF/Hope bb.

    Sorry SRAM, it's a NO from me.

  5. #5
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    Quote Originally Posted by Cerpss View Post
    Biggest takeaway from the video, prior to applying for a job at SRAM one should grow a mustache. Maybe even put a picture of you with said mustache in your resume or additional documents.
    Funny. I think that only applies to the SLO facility featured in the vid. I know several people who work for SRAM in Indianapolis, and they don't "style" their facial hair, if they have any at all.

  6. #6
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    Shimano has been using a 24mm spindle like forever. I guess if it ain't broke...why fix it?

  7. #7
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    Quote Originally Posted by RS VR6 View Post
    Shimano has been using a 24mm spindle like forever. I guess if it ain't broke...why fix it?
    I've been a fan of Shimano cranks for awhile. Things Shimano has long missed the boat on:

    removable spiders for direct mount 1x rings. Much better for rings smaller than 30t, imo.
    longer spindles for fatbikes
    introducing funky/proprietary new bcd patterns every few years just to be annoying. to be fair, SRAM and other companies are also guilty of this.

    I don't really care so much what spindle diameter my crank uses. With that said, I wouldn't want to use a 24mm spindle on a frame with a bb shell standard that would require me to use spacers/adapters to get it to work with a bb like with bb30/pf30. I just want to buy a crank and a bb and have them work together in my frame. I'm also not a fan of compromising on the bearings the way RF did with their bb that fits 30mm spindles into bb86/92 frames. I've found a bb from another company that is better than Race Face's, but still...the RF one still exists and still sucks.

    It seems to me that both SRAM and Shimano have been losing out on the midrange and better OEM market for cranks, particularly to the RF Aeffect. I have to wonder if this is at least in part a move by SRAM to start grabbing some of that OEM market back.

  8. #8
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    I read that this morning. Interesting and I do like the concept of trying to simplify parts selection and interchangeability. I've been running "old school" screw in BB's on my bikes forever. I'm still running my Action-Tec Ti BB with old school square taper Race Face crankset (94/52mm). I like being able to build up my set up and adjust my chainline.

    It's been getting harder and harder to find frames that allow this. I bought in to Race Face's Cinch setup because again, I can machine spacers and preload the bearings for what ever application I might have.

    This new SRAM set up also allows bearing preload adjustment which I think is a great thing.

  9. #9
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    Quote Originally Posted by mfa81 View Post
    I saw this and I can't really understand why 28.99?!?! I think we were just living with 24, 24/22 and 30 for too long now!
    It is that type of thing that get's riders worked up.

    Does SRAM really expect riders to believe that 1.01mm is going to fix the bearing failure issue in the PF92 shell.

    If SRAM is going to make a change, at least make it believable.

    I hope some engineer will come along and prove me wrong.

    Otherwise, I'll stick with my $95 XT cranks and BB that just won't die.

  10. #10
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    My judgment on this all hinges around the BB quality. If there's no real improvement there for value for performance, then this is lame.
    "The challenge is not in developing new ideas, but in escaping old ideas."

  11. #11
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    SRAM is basically copying Cinch with a smaller spindle.

  12. #12
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    This will essentially replace the 24/22 and 30 spindle options at least on the mountain bike side. There's no reason to 'upgrade' to this but it's way easier for SRAM and the frame manufacturers. It comes close to cutting the number for crank SKU's in half and will make life easier in the long run. If you buy a new bike later this year it could come with this and someday you will need to replace the BB bearings. Until then there's no reason to get upset at anybody.

  13. #13
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    If they can't make it better...then make it different.

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    DUB does not look compatible with my Scorpion stand.

  16. #16
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    On the other hand, if their lock ring is better than the bullshit plastic raceface one with the tiny allen screw that's impossible to get to, and if you can impossible not to strip, they might be worthwhile...

  17. #17
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    I hate this. The BBs for the old stuff aren't going away anytime soon. And Sram will probably continue to manufacture 24 and 30.

    To me, 24 is best. Give me the biggest bearing possible, I say. My XTR crank in a PF30 frame, with a Wheels threaded BB has been perfect. Insanely smooth, low drag. Even after a season of destroying it in the bike park, and dirty trail riding.

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  18. #18
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    Quote Originally Posted by FastBanana View Post
    I hate this. The BBs for the old stuff aren't going away anytime soon. And Sram will probably continue to manufacture 24 and 30.

    To me, 24 is best. Give me the biggest bearing possible, I say. My XTR crank in a PF30 frame, with a Wheels threaded BB has been perfect. Insanely smooth, low drag. Even after a season of destroying it in the bike park, and dirty trail riding.

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    To me, the strength-to-weight ratio of the 30mm axle is better and allows for a stiffer and lighter crank, it's just about having enough room for the bearings, which we did, until the stupid BB92 standard came along, which was essentially no-mans-land if you wanted to run a 30mm spindle crank, not enough room really for proper bearings and a shell. Even 24 isn't all that, as you know they moved the bearings outboard to make them big enough. And the 30mm could be stepped down anyway.
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  19. #19
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    Are bearings with a 29mm ID even common?

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    Looks like they planned to have a shim between the bearing and spindle to prevent metal-to-metal contact like Shimano BBs, with an o-ring on the spindle side, but hard to tell if it made it to production BBs.

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    - Can see that the black part isn't a black oxide metal treatment, but the slim shim, with the stainless bearing ID showing under it.

    Okay, so looks like they'll be using a bearing with a ID of at least 30mm. The shim could be 0.5mm. This shim is a big deal, as not having metal-to-metal contact means less risk of creaking. It also acts as a labyrinth seal that doesn't cause extra drag, allowing you to spray away with a hose with less risk, which will kill a bearing in short order. I question the durability of a 0.5mm shim though.

    Looks like they know their market well, the weight weenies: XX1 is 490gg including PF92 BB, lighter than RF Next SL.

    At least some coverage bothered to pass along the message that the bearings are less durable than GXP.
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  20. #20
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    Quote Originally Posted by Jayem View Post
    To me, the strength-to-weight ratio of the 30mm axle is better and allows for a stiffer and lighter crank, it's just about having enough room for the bearings, which we did, until the stupid BB92 standard came along, which was essentially no-mans-land if you wanted to run a 30mm spindle crank, not enough room really for proper bearings and a shell. Even 24 isn't all that, as you know they moved the bearings outboard to make them big enough. And the 30mm could be stepped down anyway.
    Great point.

    I guess, quality BB is the key. And too many manufacturers (Sram) make shitty BBs.

    Pf92 is retarded, I can agree there. But I do love Shimano cranks. So easy to work on, and Ive had the best luck using their cranks with all sorts of BBs without any trouble.

    I cant say the same about Sram.

    Why can't we just have threaded everything?

    (I am still testing some E13 cranks. Carbon on my DH bike, and alloy on a hardtail, and they spin smooth, but with lots of bearing drag. Thinking of trying another brand BB)

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  21. #21
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    Quote Originally Posted by Miker J View Post
    It is that type of thing that get's riders worked up.

    Does SRAM really expect riders to believe that 1.01mm is going to fix the bearing failure issue in the PF92 shell.

    If SRAM is going to make a change, at least make it believable.

    I hope some engineer will come along and prove me wrong.

    Otherwise, I'll stick with my $95 XT cranks and BB that just won't die.
    I agree, it's the 1.01mm aspect of this that stinks. Aint no improvement happening anywhere in 1.01mm. 30mm is superior and we already have that.
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  22. #22
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    Quote Originally Posted by Varaxis View Post
    Are bearings with a 29mm ID even common?
    That's also what I'm wondering.
    Are bearing manufacturers going to start making a new bearing, just increase the id of the inner race, shim, or are they already common?
    It is no measure of health to be well adjusted to a profoundly sick society.

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    Quote Originally Posted by customfab View Post
    It comes close to cutting the number for crank SKU's in half and will make life easier in the long run.
    Is there a reason why this couldn't happen with the existing 30mm applications?
    It is no measure of health to be well adjusted to a profoundly sick society.

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    Quote Originally Posted by FastBanana View Post
    I hate this. The BBs for the old stuff aren't going away anytime soon. And Sram will probably continue to manufacture 24 and 30.

    To me, 24 is best. Give me the biggest bearing possible, I say. My XTR crank in a PF30 frame, with a Wheels threaded BB has been perfect. Insanely smooth, low drag. Even after a season of destroying it in the bike park, and dirty trail riding.

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    They could of just stayed with their 24 and fit everything.

    Now you will need a new power meter as well if you use a crank arm design.

  25. #25
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    Quote Originally Posted by MudBike View Post
    DUB does not look compatible with my Scorpion stand.
    A definite consideration!! Scorpion stands ROCK!!

  26. #26
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    How can you tell it's not Scorpion compatible? There's an opening on the NDS side.

    SRAM DUB crank spindle standard-sram-dub28-640x427.jpg

    I'm also one that runs Shimano by choice. Not going to spend over 2.5x more to shave weight where it has hardly any effect.
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  27. #27
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    It's a bummer. I doubt they are that much stiffer or better. If they stop making BBs for the older SRAM 24mm cranksets then they will be obsolete. I have XX and X0 carbon cranksets that may become expensive carbon paperweights in the near future.

  28. #28
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    Quote Originally Posted by flipnidaho View Post
    SRAM is basically copying Cinch with a smaller spindle.
    I believe you mean Hollowgram.

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    Quote Originally Posted by WHALENARD View Post
    Is there a reason why this couldn't happen with the existing 30mm applications?
    Yes

    Lizards.
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  30. #30
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    Well, I'm still really happy on my "9spd", M760, 4 bolt crank from 2005, have swapped it from frame to frame and still going strong, have bought a couple more and one LX570, BBs are cheap, never felt any flex, but then again I don't weigh over 200lbs. Did pick up a newer M770, 180mm length crankset 1.5 years ago just to try what difference 5mm might make, still run all my bikes with a double, so no fuss on fitting middle ground chainrings or compromising gear range.

    Basically, like the rest of the "geniuses", they can go fvck themselves and their proprietary products.
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  31. #31
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    Quote Originally Posted by Varaxis View Post
    Okay, so looks like they'll be using a bearing with a ID of at least 30mm. The shim could be 0.5mm. This shim is a big deal, as not having metal-to-metal contact means less risk of creaking. It also acts as a labyrinth seal that doesn't cause extra drag, allowing you to spray away with a hose with less risk, which will kill a bearing in short order. I question the durability of a 0.5mm shim though.
    Wait a second, part of Sram's reasoning for the new spindle diameter (according to the two Pinkbike articles I read) was so that they could fit a bigger/better seal on the bearing, thus preventing contamination and premature bearing death. If they're using the same bearing size and shimming the spindle/bearing interface, how does that change anything in regards to the bearing seal??

    What am I missing here?
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    Stop asking how much it weighs and just go ride it.

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    Quote Originally Posted by *OneSpeed* View Post
    Wait a second, part of Sram's reasoning for the new spindle diameter (according to the two Pinkbike articles I read) was so that they could fit a bigger/better seal on the bearing, thus preventing contamination and premature bearing death. If they're using the same bearing size and shimming the spindle/bearing interface, how does that change anything in regards to the bearing seal??

    What am I missing here?
    Lol, this is the bike industry, nothing makes sense. Sram leads the way, welcome to the Thunderdome

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  33. #33
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    Quote Originally Posted by LyNx View Post
    Well, I'm still really happy on my "9spd", M760, 4 bolt crank from 2005, have swapped it from frame to frame and still going strong, have bought a couple more and one LX570, BBs are cheap, never felt any flex, but then again I don't weigh over 200lbs. Did pick up a newer M770, 180mm length crankset 1.5 years ago just to try what difference 5mm might make, still run all my bikes with a double, so no fuss on fitting middle ground chainrings or compromising gear range.

    Basically, like the rest of the "geniuses", they can go fvck themselves and their proprietary products.
    At least they said they'll still make the GXP BBs for 3 more years, but yeah. Eff that noise. I'm still on 10spd with no plans to change and my next build is going back to 2x.
    :nono: :thumbsup:

  34. #34
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    Quote Originally Posted by noapathy View Post
    At least they said they'll still make the GXP BBs for 3 more years, but yeah. Eff that noise. I'm still on 10spd with no plans to change and my next build is going back to 2x.
    They will be made by WheelManu forever. Square taper and MegaExo have been rated forever, still being made

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  35. #35
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    Quote Originally Posted by Jayem View Post
    the stupid BB92 standard came along, which was essentially no-mans-land if you wanted to run a 30mm spindle crank, not enough room really for proper bearings and a shell.
    I agree that BB92 is the dumbest bb shell standard out there, honestly. For a 30mm crank, this is the only bb I've found that's worth anything. BB92 is basically telling customers to f*ck off and that 24mm cranks are what they should be using. Well, at least some customers are telling manufacturers that they don't want to be limited to cranks with 24mm spindles.

    https://www.endurobearingsonline.com...ucts/bb86-4130

    This bb offers better, bigger bearings. More bearings. Better seals for those bearings (included in the package are 2 additional external seals that fit like spindle spacers, and I fill the space between them and the bb with yet more grease to improve the sealing even more).

  36. #36
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    Quote Originally Posted by *OneSpeed* View Post
    Wait a second, part of Sram's reasoning for the new spindle diameter (according to the two Pinkbike articles I read) was so that they could fit a bigger/better seal on the bearing, thus preventing contamination and premature bearing death. If they're using the same bearing size and shimming the spindle/bearing interface, how does that change anything in regards to the bearing seal??

    What am I missing here?
    Did I word my sentences poorly? Thought it was clearly implied that their shim was part of the new and improved sealing.

    SRAM DUB crank spindle standard-s-l1600.jpgSRAM DUB crank spindle standard-shimano-bb-mt800-xt-slx-lx-hollowtech-ii-bottom-bracket-43964-0-1481263228.jpgSRAM DUB crank spindle standard-bk.jpg
    - Poor sealing (old SRAM), solid sealing (Shimano), legendary sealing (Chris King)

    BBs die from contamination. Water intrusion from wet conditions, bike washing and/or riding through water crossings are likely culprits. The difference between long lasting and reliable Shimano BBs, crapshoot RaceFace ones, and legendary CK ones are the level of sealing, lubrication quality, and bearing design.

    SRAM DUB crank spindle standard-llb-1024x577.jpg
    - common cartridge bearing sealing. The inner race (metal ring at top of pic) spins and makes light contact with the 2 pointy bits on the seal.

    Poor designs compromise on seals and durable lubrication, for the sake of low drag, since they know that people like to judge quality based on how many rotations they get out of an axle/spindle spinning freely on it with minimal load. Some even purposely market their bearing assemblies this way (8+ crank rotations vs 3-4 on "inferior" BB). Larger diameter bearings have bigger seals and proportionally more contact area (BB30 vs 24mm bearings). They also rely on a basic washer to act as a "dust shield" to supplement the bearing's sealing, which is fairly useless vs water. Shimano goes a step further and uses their special waterproof [Dura-Ace?] grease as a barrier to protect their bearing from water intrusion. DUB puts a seal between the spindle and the dust shield to prevent water intrusion. I think DUB's seal design is excellent, with their only compromise being the larger bearing. Shimano's design relies on a tight fit that might require use of a hammer, and longevity might rely on people resisting the urge to wipe the excess lubrication away.

    All of CK's bearings have a rubber seal that has side pressure from a circlip holding it tight against the bearings. With so much of the seal touching moving parts, there's more drag, but there's worry free durability. This is the best level of sealing that you can find. They also use a shim like the DUB and Shimano to prevent metal-on-metal contact between the bearing and spindle, which is a source of creaking. The Santa Cruz Syndicate runs important races without the seals... their draggy sealing is best illustrated here: https://chrisking.com/bearing-service

    I actually like BB92. It makes the most sense from an engineering point of view, but I have no sympathy for the mistake of introducing BB30 and PF30 to mtb. Spreading the bearing spacing outboard is a huge positive step for 30mm spindle cranks though. Not sure if Hollowgram has outboard bearings, but Cinch and DUB do this.

    SRAM DUB crank spindle standard-raceface-next-sl-g4-carbon-crank.jpg
    SRAM DUB crank spindle standard-shimano-xtr-m9000-mechanical-actual-weights-cranksets02.jpg
    - Add 50g for a chainring

    I blame weight weenies and questionable logic...
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  37. #37
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    Quote Originally Posted by MudBike View Post
    DUB does not look compatible with my Scorpion stand.
    Deal breaker for me.

  38. #38
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    Quote Originally Posted by Varaxis View Post
    I actually like BB92. It makes the most sense from an engineering point of view
    What about BB86/92 makes "the most" sense from an engineering point of view? It came after 30mm cranks showed up on the market. Maybe 30mm spindles weren't common on mtb's yet, but frame mfg's continued to use BB92 shells on frames (and introduce more new bikes using them) long after 30mm cranks became common on mtb's.

  39. #39
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    You guys get worked up over all kinds of shit.

    I'm still getting parts for my 1985 Bridgestone, and you're worried about being forced into something new?

  40. #40
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    Quote Originally Posted by Harold View Post
    What about BB86/92 makes "the most" sense from an engineering point of view? It came after 30mm cranks showed up on the market. Maybe 30mm spindles weren't common on mtb's yet, but frame mfg's continued to use BB92 shells on frames (and introduce more new bikes using them) long after 30mm cranks became common on mtb's.
    Mostly because of its increased stiffness vs the type of loading on BBs and cranks see (transverse). It's akin to making head tubes longer with ZS headsets. Also, PF30 takes a significantly larger amount of real estate radially, which can affect room for chainstays, chainstay yoke/bridge, tire clearance, ISCG tabs, shock placement, pivot size/location, linkage size, cable routing, etc.

    SRAM DUB crank spindle standard-fqiq9gh.png
    - Tallboy 3. Fitting all this together would be a challenge with a larger PF30 shell

    Just not ideal to design parts to be cantilevered, investing manufacturing processes into creating redundant reinforcing material and/or threads for support, which is disposed of at the end of its life. Why not make more of it permanent?
    "The challenge is not in developing new ideas, but in escaping old ideas."

  41. #41
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    Quote Originally Posted by Varaxis View Post
    Click image for larger version. 

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    - Tallboy 3. Fitting all this together would be a challenge with a larger PF30 shell
    Except that bike has a threaded bb shell, not pressfit.

  42. #42
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    Quote Originally Posted by Harold View Post
    Except that bike has a threaded bb shell, not pressfit.
    Does it detract from the points I've made? It answered your question, along with the context, did it not? How about an example from Giant, which uses BSA on their alu frames and BB92 on their carbon frames:

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    - Stumpy FSR PF30. A larger diameter bore, even if only 5-6mm more, is clearly influencing the design of nearby structure. That's actually a lot of space from an engineering perspective. Narrow-set bearings could have been been placed outboard in the swingarm, if there was space to create thick enough material around the bearing.
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  43. #43
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    Quote Originally Posted by Varaxis View Post
    Does it detract from the points I've made? It answered your question, along with the context, did it not? How about an example from Giant, which uses BSA on their alu frames and BB92 on their carbon frames:

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    - BSA on alloy, PF92 on carbon.

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    - Stumpy FSR PF30. A larger diameter bore, even if only 5-6mm, is clearly influencing the design of nearby structure. That's actually a lot of space from an engineering perspective. Narrow-set bearings could have been been placed outboard in the swingarm, if there was space to create thick enough material around the bearing.
    It actually does matter. With a threaded BB, you can use 30mm spindles without much trouble because the bearings are outboard. BB92 is a problem because the shell is the same width as the threaded shell + bearing cups, but the bearings have to get crammed into the smaller diameter space when used with a larger spindle. It's no wonder the BB92 CINCH bottom bracket was as terrible for me as it was. There was so little space to work with when it came to the bearings, seals, and the other accoutrements. BB92 is a problem when it comes to the proliferation of 30mm spindle cranks compared to that (and I do see how the smaller diameter shell confers benefits to the placement of suspension pivots linkages, and chainstay lengths, and whatnot). BB92 is not the only way to accomplish those goals.

  44. #44
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    Quote Originally Posted by FastBanana View Post
    They will be made by WheelManu forever. Square taper and MegaExo have been rated forever, still being made

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    I haven't had good luck with the Wheels MFG GXP BBs. I toasted two of them in just a few months. The SRAM BB has been going strong for year now. I think I will just have to load up on SRAM BBs to keep my XX and X0 cranksets still valid.

  45. #45
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    Quote Originally Posted by Harold View Post
    It actually does matter. With a threaded BB, you can use 30mm spindles without much trouble because the bearings are outboard. BB92 is a problem because the shell is the same width as the threaded shell + bearing cups, but the bearings have to get crammed into the smaller diameter space when used with a larger spindle. It's no wonder the BB92 CINCH bottom bracket was as terrible for me as it was. There was so little space to work with when it came to the bearings, seals, and the other accoutrements. BB92 is a problem when it comes to the proliferation of 30mm spindle cranks compared to that (and I do see how the smaller diameter shell confers benefits to the placement of suspension pivots linkages, and chainstay lengths, and whatnot). BB92 is not the only way to accomplish those goals.
    BB92 has a 41mm ID. BB30 has a 42mm ID; it was designed for bearings without an external cup. PF30 was the adaptation of BB30 to MTB, pushed by SRAM and a collaboration with bike brands for numerous profit-driven reasons; it has a 46mm ID. Only a small number of BB30 spindles are made with outboard bearing spacing in mind.

    BB30 came from the road side, introduced by Cannondale. I blame weight weenies and those with questionable logic for supporting BB30/PF30. Why do you want the proliferation of BB30? You're blaming BB92 for being a problem for BB30. Why? Because it has strong merits that rival BB30? Is your BB30 crank is influencing your bike build so much that it's almost as if you're building around a BB30 crank, limiting your choices to frames that play nice with it? Is that wiser than considering the bike as a complete system? If weight is a primary driver, then what about the fact that early BB30 designs weren't really any lighter than 24mm equivalents. It's still a very small difference in Eagle cranks:

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    I don't believe that it's a coincidence that designs are reverting back to what worked. FSA saw this problem before, introducing BB386, but they didn't collaborate with OEMs on the same level as SRAM to push their idea, nor forcibly try to eliminate/replace other standards, instead just trying to play nicely with various standards, including BBRight. Widely spaced bearings and now this style of sealing with this shim were things that worked for Shimano for decades. What market is DUB going to hurt? GXP is likely gone, and the BB30 might get hit a bit. I don't see Shimano-compatible 24mm going anywhere. In fact, I wonder if people will switch back to 24mm because of the disgust that 30mm spindles have given people. Downsizing to 29mm (sanded to 28.99mm to slide easier?), doesn't seem to address the BB92 issue with compromised bearings, considering the shim that was added for "durability".

    If anyone cares about the stiffness side of things: having the spindle attached permanently attached to the driveside, increases stiffness greatly on that side, compared to being attached by spline and fasteners (props to SWorks/Lightning crank design). Attaching ring by spider also increases stiffness, especially lateral stiffness, though the design of the DM arms of Eagle rings is very stiff compared to the RF DM design. XTR stiffness is likely still unrivaled (100+ N/mm vs ~80 of competing carbon cranks). *According to Fairwheel bikes, the power losses are small, yet measurable, but a stiff crank provides psychological and 'feel' benefits, also incrementally improving efficiency by keeping things aligned
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  46. #46
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    SRAM DUB crank spindle standard-kona-honzo-cr-race-275554-17.jpg
    - More PF92 structural design, taking advantage of the extra width (Kona Honzo CR)

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    - S-Works Epic HT PF30 comparison

    New coverage with words right from the maker: Deep dive into SRAM’s new DUB system - Mtbr.com

    "What makes the bearings more durable if they are smaller bearings vs. the bearing system they are replacing?"
    "In all of our development, lab testing and field evaluation of the DUB BB we found that the durability of the bearings on a bicycle bottom bracket are much more influenced by the sealing and contamination of the system vs. the size of the balls. We found that smaller ball sizes can far surpass the durability of larger ball sizes if the smaller balls are sealed better from contamination. It is the contamination that almost always is the cause of poor durability in a bicycle bottom bracket. And that is exactly why we did not follow some of our competitors and just use a 30mm system that limits sealing in certain configurations. We needed the extra room for proper sealing to ensure our BB durability."

    Having that extra space between the crank arm and BB, needing a preload adjuster and spacer(s), probably doesn't help.
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  47. #47
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    Quote Originally Posted by Jayem View Post
    To me, the strength-to-weight ratio of the 30mm axle is better and allows for a stiffer and lighter crank, it's just about having enough room for the bearings, which we did, until the stupid BB92 standard came along, which was essentially no-mans-land if you wanted to run a 30mm spindle crank, not enough room really for proper bearings and a shell. Even 24 isn't all that, as you know they moved the bearings outboard to make them big enough. And the 30mm could be stepped down anyway.
    Except it isn't. Unless it's made of junk grade steel, a 24mm steel spindle has a similar stiffness and strength to weight ratio as a 30mm aluminum axle. I worked out the math some time ago and the difference was pretty much a rounding error with a pretty common steel like 4340. Upgrade it to something nice like 300M or Aermet 100 and steel ends up being way stronger compared to a 30mm spindle in any aluminum alloy.

    I'm in complete agreement with Varaxis, BB30 is roadie crap that got foisted off on mountain bikers. On road bikes it sorta makes sense since you can get narrower Q-factors on cranks for (insert roadie reasons), but on a mountain bike it's stupid. Narrow Q-factor on a mountain bike just means you'll bash the cranks and/or your feet into the stays, and you can't space things that far in anyway or else the chain goes into the tire or you put the chainrings into the chainstay. So on a mountain bike you end up using a longer spindle and a bunch of spacers on both sides of a BB30 setup which is just fakking stupid. Instead of getting rid of the spacers and moving the bearings outward to better support the spindle, it keeps the same narrow roadie spacing and puts the cranks further out where they put more leverage & load on the bearings & frame. And you wonder why the stupid things creak and fail all the time.

    BB92 isn't perfect but at least it's reasonably well designed. It puts the bearings as far outboard as possible to properly support the spindle. I would like to see larger bearings but at least they're decently sealed, and with Shimano's BBs they use a shim between the bearings & spindle that ensures a good fit to help prevent fretting damage and creaking.

  48. #48
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    Quote Originally Posted by Varaxis View Post
    Did I word my sentences poorly? Thought it was clearly implied that their shim was part of the new and improved sealing.
    No, I just misunderstood what was going on. That was the mother of all explanations! Thanks for clearing up my (and I'm sure many others) confusion. Good reading, thanks for all the details and time it took to write up all those responses.
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  49. #49
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    Super educational thread!!
    Pertinent to me as I'm pondering going into the nether world of PF92. Or just retreating to PF30 or ancient times BSA. LOL

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    Quote Originally Posted by aliikane View Post
    I haven't had good luck with the Wheels MFG GXP BBs. I toasted two of them in just a few months. The SRAM BB has been going strong for year now. I think I will just have to load up on SRAM BBs to keep my XX and X0 cranksets still valid.
    Try out a Hope 24mm bottom bracket with GXP adapter. Bulletproof. I just installed three of them with GX Eagle and X01 Eagle GXP cranks.

  51. #51
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    Quote Originally Posted by WHALENARD View Post
    Is there a reason why this couldn't happen with the existing 30mm applications?
    BB92 is the big reason, there's not enough room in that shell to squeeze a durable bearing and the 30mm spindle. IIRC, BB92 was developed by Shimano as a press fit option for their cranks. Since they dug their heels in a long time ago and said NO!!! to 30mm spindles there were no considerations for that sized spindle when they designed BB92.

  52. #52
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    Quote Originally Posted by customfab View Post
    IIRC, BB92 was developed by Shimano as a press fit option for their cranks. Since they dug their heels in a long time ago and said NO!!! to 30mm spindles there were no considerations for that sized spindle when they designed BB92.
    Cannondale introduced BB30 in 2000. At this time, Shimano was the only game in town with their Octalink (and v2) setting the only truly worthy standard. Square taper and ISIS crank setups were flexy and the BBs blew up easily (SKF ISIS BBs were an exception). Around this time, Shimano decided to permanently attach the spindle to their cranks with outboard BB (Hollowtech 2), and most others followed suit to ditch flexy crank setups and ISIS. Leading up to this point was a hot time for new crank tech, churning out colorful ano CNC'd cranks that solved nothing, but at least looked cool (Sweet Wings was an exception, also introducing an outboard BB).

    In 2006, Shimano collaborated with Scott and possibly some other mfgs (Giant and Pivot?) to introduce BB92/BB86 (41A/41B). Trek introduced BB95/BB90 in 2007, which was like BB92/86 without the retaining cups, putting bearings directly into the shell like BB30. The biggest advantage was stiffness, some quoting 10% additional pedaling stiffness over model versions with a threaded BB, on top of being lighter.

    Cannondale opened up its BB30 standard to all in 2006, but the industry soon learned that the tolerances needed to pull it off was cost prohibitive. Consumers ended up playing the lotto with frames that lacked good tolerances, likely ending up with a creaky mess, being advised to counter it using special press-fit adhesives.

    SRAM created PF30 in 2009, promising to be more forgiving of loose tolerances. Mfgs jumped on the opportunity to save on mfg costs, especially carbon frame makers (no need to co-mold and machine alloy BB shells). Mfgs were also being sold on the fact that it accepted all cranks with adapters. Consumers still ended up playing the lotto with creaky frames. Consumers were faced to deal with the problems with press-fit adhesives (special loc-tite), RTV gasket, buying machined alloy BB cups with o-rings and/or expanders (e.g. collet) that were one-piece or threaded shells to address BB cups being walked out and to address poor concentricity and other tolerance issues. Cranks relied on preload adjusters and spacers to fill space between the crank arms and BB. Spec marketed their implementation as OSBB, citing tighter tolerances, to avoid being bunched with the others giving PF30 a bad name.

    Enter numerous standards that didn't proliferate: GXP, BBRight, 386EVO, M30, M35, T47... SRAM bought GXP from TruVativ; no one else built cranks for GXP. BBRight and 386EVO were created to widen BB shells and the bearing spacing, increasing stiffness. M30 was a combination of GXP's stepped NDS bearing idea with BB30. M35 promised even better stiffness to weight, and potential use of carbon as a spindle material. T47 was an indy collab to make PF30 shells threaded.

    Now DUB enters the fray, to address the issue of BB30 BBs not having sealing as good as the 24mm variants, and to widen the bearing spacing. Reduced the spindle size 1mm to make room for a seal/shim that was present on Shimano BBs since the early 2000s, that took up tolerance between the spindle and bearing, reducing water intrusion and creaking from a loose metal-on-metal press fit.
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  53. #53
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    Quote Originally Posted by customfab View Post
    BB92 is the big reason, there's not enough room in that shell to squeeze a durable bearing and the 30mm spindle. IIRC, BB92 was developed by Shimano as a press fit option for their cranks. Since they dug their heels in a long time ago and said NO!!! to 30mm spindles there were no considerations for that sized spindle when they designed BB92.
    Yep, I agree, and use gxp on my BB92 bike for this reason.

    I guess my question is why can we not simply increase the diameter of bb92 to bb30/30mm to accept the already existing and very good 30mm spindle/bearings in existence? Is there a reason why we can not combine the width benefits of bb92 with the diameter benefits of bb30?

    Barring a reason I can not see (and there may be one, I'm not an engineer), this is what sram just did but by a difference of 1.01 making the DUP momentarily proprietary to them.
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  54. #54
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    Quote Originally Posted by WHALENARD View Post
    I guess my question is why can we not simply increase the diameter of bb92 to bb30/30mm to accept the already existing and very good 30mm spindle/bearings in existence? Is there a reason why we can not combine the width benefits of bb92 with the diameter benefits of bb30?
    Good question. This touches on a big part of the problem IMO. Frame manufacturers and component manufactures don't communicate well enough. If the BB92 is problematic with 30mm spindles, why don't we fix it or just do away with it? Second question: is every BB/crank manufacturer having trouble with BB92 shells or just Sram? Third question, why keep using any "standard" that isn't good?

    Perfect example is Dub, Sram claims this all came about because companies building frames keep using the BB92 shell, so they were forced to create a new, better, spindle and BB because of "demand from the consumer." Ha!

    That's a bunch of marketing BS IMO. Where are all these consumers that were asking for a new standard? Sram wanted to create something new that was just theirs, even if temporarily. Wether it's a reaction to RF products or whatever I don't know or care, it wreaks of Boost BS.

    Sorry, I just can't ignore the marketing BS in the couple articles I've read. Yes, I get the fact that DUB will work in any current frame and bla bla bla, but these silly 1mm changes just for the sake of selling new products needs to stop. (I know it's nothing new, and I'm not even talking about bike manufacturers who intentionally make proprietary stuff like Cannondale or Spec., but Sram is a repeat offender.)

    Small manufacturers are guilty too, and I just don't get it. Last year I built a bike and my goal was for it to be entirely Made in the USA. I wanted to use White Industries cranks but after contacting them I learned they have their own proprietary direct mount interface that means I can only use their chainrings. UGH. Sorry, deal breaker.

    As any manufacturer in a shrinking market, I would want my products to be as universal and versatile as possible. "Yes, please use our product on your everyday bike, or on your non-mainstream build."
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  55. #55
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    Lots of skepticism it seems?!? I’m down for it...looks like a good all in one system to me


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  56. #56
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    Me thinks I’m just gonna get an XT crankset and not worry about my cranks.
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  57. #57
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    Quote Originally Posted by Varaxis View Post
    Does it detract from the points I've made? It answered your question, along with the context, did it not? How about an example from Giant, which uses BSA on their alu frames and BB92 on their carbon frames:

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    - BSA on alloy, PF92 on carbon.

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    - Stumpy FSR PF30. A larger diameter bore, even if only 5-6mm more, is clearly influencing the design of nearby structure. That's actually a lot of space from an engineering perspective. Narrow-set bearings could have been been placed outboard in the swingarm, if there was space to create thick enough material around the bearing.
    Pretty sure Giant switched ALL their mid/high level frames to BB92 around 2013 or 2014. My alu '14 Trance has BB92 and the new '18 stuff does as well (at least Trance/Anthem - I didn't check others since not really interested in them).
    :nono: :thumbsup:

  58. #58
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    To me, the 28.99mm spindle is just amusing. Its not 28 or 29, but 28.99mm. Haha. The .01mm can't be significant because it is so minute. The thickness of a piece of paper is gigantic (.1mm) compared to .01mm. I don't think they can get their tolerances within .1mm let alone .01mm.

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    Quote Originally Posted by intheways View Post
    Me thinks I’m just gonna get an XT crankset and not worry about my cranks.
    This x 1000. Shimano had had interchangable bbsfor years, and they make the best aluminum cranks in the business. Carbon fiber is wonderful stuff, but not convinced it's the best material to make cranks from.

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