Rhp Bearings Technical Handbook For Professional Mountain

[Alberta Hagley]

This comprehensive guide tells you everything you need to know about bottom brackets \u2014 from a breakdown of all the bottom bracket systems available and their compatibility with one another to how a bottom bracket works and how to stop a bottom bracket creaking, this guide has it all.\nIt wasn\u2019t long ago that the only major bottom bracket decisions you had to make were shell width, spindle length, and, in rare cases, English (BSA) or Italian threading. These days, it can feel as though there are as many \u2018standards\u2019 as there are bike brands, with every one of them supposedly being the best option.\nBelow we rundown each of the major bottom bracket systems currently available, along with advantages, disadvantages, notes on compatibility, and some input from their proponents on why they exist.\n

\n
• What is a bottom bracket?\n
• BikeRadar\u2019s complete guide to headsets\n\n\n \n \n
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  • Conventional\/BSA threaded\n
  • BB90 and BB95\n
  • PF86 and PF92\n
  • BB30\n
  • OSBB (road)\n
  • BB30A and BB30-83 Ai\n
  • PF30\n
  • OSBB (mountain)\n
  • PF30A and PF30-83 Ai\n
  • BBRight\n
  • BB386 EVO\n
  • T47\n
  • Threadfit 82.5\n
  • SRAM DUB\n\n\n\n \n \n\nBefore we get stuck into the nitty-gritty of each standard though, we\u2019ve put together this helpful crib sheet that runs through all of the key specifications.\n
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    • The ultimate creaky bottom bracket fix\n
    • Road bike groupsets: everything you need to know\n\nBottom bracket standards and compatibility\nISO threaded internal\nProprietary?\u00a0No
      \nBB shell inner diameter\u00a01.37in x 24 TPI
      \nBearing inner diameter\u00a0N\/A, internal BBs have integrated spindle
      \nBB shell width\u00a068mm road, 73mm mountain, 83mm downhill, 100\/120mm fat bike
      \nInstallation\u00a0Threaded internal bearings
      \nCompatibility\u00a0Square taper, Octalink, ISIS
      \nOther names\u00a0BSA or BS threaded
      \nOther notes\u00a0Bottom bracket must be specced with correct shell width and spindle length\nISO threaded external\nProprietary?\u00a0No
      \nBB shell inner diameter\u00a01.37in x 24 TPI
      \nBearing inner diameter\u00a024mm (Hollowtech II), 24\/22mm (GXP), 25mm (Ultratorque\/Powertorque)
      \nBB shell width\u00a068mm road, 73mm mountain, 83mm downhill, 100\/120mm fat bike
      \nInstallation\u00a0External cups
      \nCompatibility\u00a0n\/a
      \nOther names\u00a0BSA or BS threaded
      \nOther notes\u00a0External cups now exist that will take 30mm spindles\nItalian threaded\nProprietary?\u00a0No
      \nBB shell inner diameter\u00a01.375in (34.92mm) x 24 TPI
      \nBearing inner diameter\u00a024mm (Hollowtech II), 24\/22mm (GXP), 25mm (Ultratorque\/Powertorque)
      \nBB shell width\u00a070mm
      \nInstallation\u00a0External or internal
      \nCompatibility\u00a0n\/a
      \nOther names\u00a0n\/a
      \nOther notes\u00a0Can be prone to undoing itself because non-driveside is a standard thread\nBB90\/BB95\nProprietary?\u00a0Yes (Trek)
      \nBB shell inner diameter\u00a037mm
      \nBearing inner diameter\u00a024mm
      \nBB shell width\u00a090mm road, 95mm MTB
      \nInstallation\u00a0Pressed bearings with stepped BB shell
      \nCompatibility\u00a0Designed specifically for 24mm spindles, no 30mm option
      \nOther names\u00a0n\/a
      \nOther notes\u00a0The extra width of the BB cups is replaced with more frame real-estate\nBB86\/BB92\nProprietary?\u00a0No
      \nBB shell inner diameter\u00a041mm
      \nBearing inner diameter\u00a024mm
      \nBB shell width\u00a086.5mm road, 91.5mm MTB. Other widths may be named according to shell dimensions: 89.5mm, 104.5mm, 107mm, 121mm, 132mm
      \nInstallation\u00a0Bearings pressed in cups
      \nCompatibility\u00a0Originally designed for 24mm spindles, but some BBs that fit a 30mm spindle are available
      \nOther names\u00a0PF41 (Hope \u2013 refers to BB shell diameter), PF24 (Chris King \u2013 refers to spindle diameter)
      \nOther notes\u00a0Similar to above, but a non-proprietary version with less stringent tolerances\nBB30\nProprietary?\u00a0No (open Cannondale standard)
      \nBB shell inner diameter\u00a042mm
      \nBearing inner diameter\u00a030mm
      \nBB shell width\u00a068mm road, 73mm MTB
      \nInstallation\u00a06806 bearings pressed into frame with circlips to locate in BB shell
      \nCompatibility\u00a0Designed for specific BB30 cranks, 24mm step-down spacers available
      \nOther names\u00a0n\/a
      \nOther notes\u00a0Narrow overall width means longer spindles can be used with appropriate spacers\nBB30A and BB30-83 Ai\nProprietary?\u00a0Yes (Cannondale)
      \nBB shell inner diameter\u00a042mm
      \nBearing inner diameter\u00a030mm
      \nBB shell width\u00a073mm (BB30A), 83mm (BB30-83)
      \nInstallation\u00a06806 bearings pressed into frame with circlips to locate in BB shell
      \nCompatibility\u00a0n\/a
      \nOther names\u00a0n\/a
      \nOther notes\u00a0Asymmetric BB shell which is wider on non-driveside. Wider overall shell is also claimed to improve bearing support\nPF30\nProprietary?\u00a0No (SRAM)
      \nBB shell inner diameter\u00a046mm
      \nBearing inner diameter\u00a030mm
      \nBB shell width\u00a068mm road, 73mm MTB
      \nInstallation\u00a06806 bearings in cups
      \nCompatibility\u00a0Originally designed for BB30 cranks
      \nOther names\u00a0n\/a
      \nOther notes\u00a0Analogous to BB30 above, but uses pressed cups (with identical bearings) for relaxed manufacturing tolerances\nOSBB (Road)\nProprietary?\u00a0Specialized
      \nBB shell inner diameter\u00a042mm
      \nBearing inner diameter\u00a030mm
      \nBB shell width\u00a068mm
      \nInstallation\u00a0Pressed 6806 bearings with circlips in BB shell
      \nCompatibility\u00a0Designed for specific BB30 cranks
      \nOther names\u00a0n\/a
      \nOther notes\u00a0OSBB for Specialized Road bikes appears to just be BB30. An older Pressfit 61x46mm BB appears to be obsolete\nOSBB (Mountain)\nProprietary?\u00a0Specialized
      \nBB shell inner diameter\u00a046mm
      \nBearing inner diameter\u00a030mm
      \nBB shell width\u00a073mm
      \nInstallation\u00a06806 bearings in cups
      \nCompatibility\u00a0Originally designed for BB30 cranks
      \nOther names\u00a0n\/a
      \nOther notes\u00a0OSBB for mountain bikes appears to be PF30 (post 2010). An older 84.5x46mm BB appears to be obsolete.\nPF30A and PF30-83 Ai\nProprietary?\u00a0Yes (Cannondale)
      \nBB shell inner diameter\u00a046mm
      \nBearing inner diameter\u00a030mm
      \nBB shell width\u00a073mm (BB30A), 83mm (BB30-83)
      \nInstallation\u00a06806 bearings in cups
      \nCompatibility\u00a0n\/a
      \nOther names\u00a0n\/a
      \nOther notes\u00a0Essentially the Pressfit version of BB30A and BB30-83\nBBRight (Direct Fit)\nProprietary?\u00a0No (Cerv\u00e9lo)
      \nBB shell inner diameter\u00a042mm
      \nBearing inner diameter\u00a030mm
      \nBB shell width\u00a079mm (road only)
      \nInstallation\u00a06806 bearings pressed into frame with circlips to locate in BB shell
      \nCompatibility\u00a0BBRight cranks and wider
      \nOther names\u00a0n\/a
      \nOther notes\u00a0Similar asymmetric concept as Cannondale Ai, but the shell is wider\nBBRight (Press Fit)\nProprietary?\u00a0No (Cerv\u00e9lo)
      \nBB shell inner diameter\u00a046mm
      \nBearing inner diameter\u00a030mm
      \nBB shell width\u00a079mm (road only)
      \nInstallation\u00a06806 bearings in cups
      \nCompatibility\u00a0BBRight cranks and wider
      \nOther names\u00a0n\/a
      \nOther notes\u00a0Similar asymmetric concept as Cannondale Ai, but the shell is wider\nBB386EVO\nProprietary?\u00a0No (FSA)
      \nBB shell inner diameter\u00a046mm
      \nBearing inner diameter\u00a030mm
      \nBB shell width\u00a086.5mm road
      \nInstallation\u00a06806 bearings in cups
      \nCompatibility\u00a0Will take 386EVO cranks and traditional external BB cranks
      \nOther names\u00a0n\/a
      \nOther notes\u00a0Matches the wide bearing spacing of a BSA external BB with a large 30mm spindle\nBB392EVO\nProprietary?\u00a0No (FSA)
      \nBB shell inner diameter\u00a046mm
      \nBearing inner diameter\u00a030mm
      \nBB shell width\u00a091.5mm MTB
      \nInstallation\u00a06806 bearings in cups
      \nCompatibility\u00a0Will take 386EVO cranks and traditional external BB cranks
      \nOther names\u00a0n\/a
      \nOther notes\u00a0Matches the wide bearing spacing of a BSA external BB with a large 30mm spindle\nT47\nProprietary?\u00a0No (Chris King & Argonaut Cycles)
      \nBB shell inner diameter\u00a0M47 x 1
      \nBearing inner diameter\u00a030mm
      \nBB shell width\u00a068mm road, 73mm MTB
      \nInstallation\u00a0Threaded cups with bearings
      \nCompatibility\u00a0Cross compatible dependent on spindle length
      \nOther names\u00a0Thread Fit 30i
      \nOther notes\u00a0Aims to solve creaking issues of press fit systems. Essentially an oversized BSA external BB\nThread Fit 82.5\nProprietary?\u00a0Yes (Colnago)
      \nBB shell inner diameter\u00a041mm (when shell is fitted)
      \nBearing inner diameter\u00a024mm (30mm)
      \nBB shell width\u00a086.5mm road
      \nInstallation\u00a0Threaded BB shell takes aluminium shell, which is then fitted with BB86 bearing cups
      \nCompatibility\u00a0Originally designed for BB86 cranksets and bearings. New integrated CeramicSpeed BB fits 30mm spindle cranks
      \nOther names\u00a0n\/a
      \nOther notes\u00a0Threaded shell can be made with better tolerances and can be replaced if it wears out. CeramicSpeed now offers a fully integrated bearing (akin to T47) that will fit 30mm spindles\nWe\u2019ve also included a section on how you can (or can\u2019t as the case may be) change between different bottom bracket standards and an explainer on why there are so many standards in the first place.\nConventional\/ISO\/BSA threaded bottom brackets\nModern, external cup threaded bottom brackets are among the most common of standards. Square taper bottom brackets also fit in most shells designed for external cup bottom brackets, but to keep things simple, we will only cover the modern standard here.\nThe idea is simple, by moving the bearings outboard of the shell, you can then use a much larger spindle. Currently, 24mm is the accepted norm compared to square-taper\u2019s relatively minuscule 17mm diameter.\nExternal bottom brackets for 30mm spindles do exist, such as those from\u00a0White Industries, allowing modern 30mm-diameter axle cranks to be used.\nShimano popularised the concept as Hollowtech II, with the introduction of the XTR M960 group in 2003 \u2014 even now it\u2019s still arguably the gold standard for bottom brackets. In fact, companies such as Santa Cruz continue to stand by it despite the plethora of other options now available.\n
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      • The \u2018new\u2019 bottom bracket standard we can all get behind\n\n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n Conventional threaded bottom brackets are still very popular, and for good reason. Canyon, for example, stuck with a threaded shell on its top-end Ultimate CF SLX road frame until 2012 Immediate Media\n\u201cThreaded bottom brackets are compatible with the largest range of cranks [and] some press-in bottom brackets have a reputation for creaking,\u201d Santa Cruz global marketing manager, Will Ockelton, tells BikeRadar.\n\u201cPress-in bottom brackets require special tools, which most consumers don\u2019t have [and] they can only be installed a few times before it\u2019s recommended that you replace the bearings [or cups \u2014 ed.]. Most of our bikes come with ISCG tabs, but for the few that don\u2019t, a thread-in bottom bracket still allows for chain guide mounting.\n\u201cA threaded bottom bracket is great because it isolates the bearing from the frameset,\u201d adds Matt Harvey, president of bearing, seal and bottom bracket maker Enduro.\n\u201cBecause you have aluminium threads and surfaces, you can face the shell with a cutter and make it parallel if it is not. The bearing bores are usually round already, with aluminium cups, because it is a machined surface, and if the bearing bores are too tight you can sand them out and get the fit just right for the bearings before you thread them into the frame. You cannot use a facing or cutting tool that I know of in a carbon shell.\u201d\n
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        • Pros: Easy at-home service; interface surfaces can often be machined; huge selection of parts and accessories\n
        • Cons: Heavier than press-fit systems; frame design limited by relatively small-diameter and narrow shell\n
        • Crank designs that will fit: Standard 24mm external type (Shimano Hollowtech II, SRAM GXP, Campagnolo Ultratorque and Powertorque, FSA MegaExo, Race Face X-Type, etc), square taper, ISIS, BB386EVO, BB392EVO many others. Crucially external cups that fit 30mm spindles do exist.\n\nA note on other threaded bottom bracket standards\nTo make matters even more confusing, there exists a number of other threaded bottom bracket standards.\nExcluding the relatively new T47 standard (more on that later), the one you\u2019re most likely to come across is the Italian threaded bottom bracket.\nTo keep matters simple, we\u2019ve put together a simple explainer on this slightly esoteric of standards here.\n
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          • What is the difference between an Italian and BSA bottom bracket?\n\nBB90 and BB95 bottom brackets\nTrek introduced the proprietary BB90 standard in 2007 on the revamped Madone and soon followed with the mountain bike-specific BB95.\nInstead of bearing pressed into aluminium cups that were then threaded into the frame, Trek pressed the bearings directly into the frame.\nBearing seats were moulded into the carbon frame structure to save weight, and bottom bracket shell width ballooned to 90mm on road bikes and 95mm on mountain bikes, creating more real estate for frame tubes and suspension pivots.\nEffectively,\u00a0the space previously taken up by the bearing cups can now be used as frame real-estate, allowing larger (and stiffer) tubes to be used.\n
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            • Is Trek all-in on T47? Why I won\u2019t miss BB90, the worst bottom bracket standard\n\n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n Trek\u2019s BB90 system uses the same bearings and bearing locations as a conventional threaded system, but eliminates the cups entirely. Bearings are pressed directly into precision-molded carbon seats Immediate Media\n\u201cThe most significant [advantage] is a stiffer frame,\u201d says Trek mountain bike product manager John Riley. \u201cSecondarily, BB90\/95 offers a lighter overall solution by replacing traditional alloy bearing cups with integrated carbon bearing bores. It also provides a simplified installation process.\u201d\nAside from omitting the cups, the BB90\/95 setup is functionally identical to conventional threaded bottom brackets, in that it uses the same bearings and the same bearing locations as before. Crankset compatibility is thus unchanged, although you do lose the ability to run chain guides that sandwich between the driveside cup and frame.\nThis system is not without its issues however, with shells becoming oversized (due to wear) being a relatively common problem (leading Trek to release the very slightly oversized V2 bearings to compensate).\nPerhaps partly due to these issues, Trek has, in fact, recently abandoned this bottom bracket standard on its Domane endurance road bike platform for 2020, in favour of the T47 threaded standard. It will be interesting to see if this trend carries over to future models in its range.\n
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              • Pros: Lighter than conventional setups but retains compatibility with \u2018legacy\u2019 cranksets; creates a wider BB shell without affecting crank width\n
              • Cons: Can\u2019t use cup-mounted chain guides; shell is wider but still small in diameter; requires a separate bearing puller and press for service, bearing bores can wear out and loose tolerances\n
              • Crank designs that will fit: Standard 24mm external-type only. A GXP conversion kit is also available\n\nBB86 and BB92\u00a0bottom brackets\nVery closely related to Trek\u2019s BB90\/BB95 system is the BB86\/BB92 standard used by Scott, Giant, Pivot, and many others.\nOnce again, the bearings and their locations are identical to those of conventional threaded bottom brackets, only they\u2019re mounted in small composite cups before being pressed into the frame.\nThe advantages are similar to those for Trek\u2019s BB90\/95; a wider bottom bracket shell that doesn\u2019t otherwise affect crank width, plus lighter weight compared with threaded alloy cups.\nFrom a manufacturing standpoint, BB86\/92\u2019s dimensional tolerances aren\u2019t as stringent as BB90\/95\u2019s, and it\u2019s easier to adapt the system into alloy frames. So long as you have a concentric bore of the right diameter, parallel faces, and a proper shell width, you\u2019re good to go.\n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n PF86\u2019s wider shell allows the chainstays to be pushed further apart \u2013 a big advantage for \u2018cross bikes Immediate Media\n\u201cBecause of this technology, we\u2019re able to improve pedalling stiffness [by about] 10% on some of our frames, over traditional threaded bottom brackets,\u201d says Giant global marketing director Andrew Juskaitis. \u201c[PF86\/92 is] less subject to tolerances, too, and is able to take up +\/- 0.5mm of [shell width] discrepancy.\u201d\nScott US marketing and PR director Adrian Montgomery touts similar reasons for his company choosing BB86\/92 over other standards:\n\u201cWe can create frames with a wider bottom bracket shell, thus adding stiffness to the entire structure as the adjoining tubes can also be wider. We can do this without creating our own crank spindle standard because it adheres to the same spindle that a threaded BB uses. It\u2019s also lighter than a threaded BB because we\u2019ve removed the alloy material that held the bearings outside the shell [and] it costs less to do a press-fit bottom bracket in regards to manufacturing. Disadvantages? None that I can see.\u201d\nThe road standard has an 86.5mm shell width (hence BB86) whilst the mountain bike standard has a 91.5mm shell width. A number of other shell widths may also exist, though they all use the same bearing cups.\nMore recently, bearings have shown up that allow a 30mm spindle to be used. The dimensional restriction mean the bearings are generally quite small, as the system was designed around 24mm spindles. This can lead to reduced bearing lifetimes.\nThis system has a number of different names depending on who you talk to. It is also called PF86, PF92, PF24 (Chris King) and PF41 (Hope).\n
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                • Pros: Same as BB90\/95\n
                • Cons: Same as BB90\/95 in theory, but in practice there are generally less issues experienced due to the less stringent tolerances\n
                • Crank designs that will fit: Standard 24mm external-type, 30mm spindle bottom brackets are available for e.g. BB386 EVO, BB392EVO\n\nBB30 and OSBB\u00a0\u00a0bottom brackets\nSeveral companies have dabbled in alternative bottom bracket standards over the years (Gary Fisher, Klein, and Merlin, to name just three) but it wasn\u2019t until Cannondale released its then-proprietary BB30 system as an open standard in 2006 that something actually stuck.\nBB30\u2019s bearing cartridges press directly into a precision-fit shell, as with Trek\u2019s BB90\/95 system \u2014 albeit with the additional aid of two pairs of snap-rings\/C-Clips.\nBut here it\u2019s the shell and spindle diameters that increase in size, not the shell width.\nThe key benefits are lighter weights owing to the larger, 30mm-diameter aluminium spindle and the elimination of separate bearing cups. Plus, because the shell is still just 68mm wide, the cranks can also be made to provide more heel clearance \u2014 or, depending on the crank design, an even a narrower stance width (commonly referred to as Q factor).\n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n Proper BB30 bottom brackets require extensive and careful machining inside the shell in order to work properly \u2013 and quietly Immediate Media\n\u201cThe idea was that, since Cannondale had control of both the frame and crank manufacturing, we could use system integration to design a superior solution, even if that meant not relying on a traditional industry standard,\u201d says Cannondale vice president of R&D, Chris Peck. \u201c[Advantages are] a lighter and stiffer crank with the 30mm alloy spindle; more room in the bottom bracket area to attach larger down tubes, seat tubes, and chainstays; and very low bottom bracket weight.\u201d\n\u201c[Our] Hollowgram SiSL2 crank with SpideRing weighs 484g. By comparison, Dura-Ace 9000 weighs around 678g [we recorded 637g in our review \u2013 ed]. In addition to weight, another BB30 advantage is stiffness. By increasing the spindle diameter, you increase its resistance to twisting, which is where the bulk of the deflection in a crankset comes from. Roughly 70% of total deflection measured at the pedal comes from axle twist.\u201d\nBB30 shells, however, do require more stringent dimensional tolerances to work well, meaning that they\u2019re more expensive to manufacture. Moreover, with the notable exception of Felt, which uses a carbon tube, BB30 also usually employs an alloy shell insert that has to be bonded or co-moulded into an otherwise carbon frame.\nSpecialized\u2019s uses this standard for some of its high-end road bikes, but calls it OSBB.\n
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                  • Pros: Lighter weight; more resistant to axle twist; more heel clearance; larger-diameter shell and spindle; potential for narrower pedal stance width\n
                  • Cons: Shell still just 68mm wide; metal-on-metal interfaces can be prone to creaking; requires a separate bearing puller and press for service; requires high manufacturing tolerances; bearing seats can\u2019t easily be faced post-manufacturing\n
                  • Crank designs that will fit: BB30, BB386 EVO, standard 24mm external-type, Specialized OSBB, BBRight. Can be adapted to almost any standard with suitable adapters.\n\nBB30A and\u00a0BB30-83 Ai\u00a0bottom brackets\nMore recently, Cannondale announced a variant of BB30 called BB30A. This uses a shell that\u2019s 5mm wider than the original but it\u2019s an asymmetrical layout that only adds those extra millimetres on the non-driveside. According to Cannondale, this allows for wider bearing spacing and better spindle support (which should improve bearing longevity).\nOther critical dimensions, such as bearing outer diameter and thickness, remain unchanged and there\u2019s also no difference in pedal stance width or ankle clearance (in most cases).\nThat extra 5mm can complicate crank compatibility, however. BB30-compatible cranks that feature axle spacers on the non-driveside (such as from Cannondale and SRAM) will work just fine because all you\u2019ll have to do is remove spacers as needed to accommodate the extra width, but BB30 cranks without such spacers (such as from FSA and Specialized) won\u2019t work.\nThankfully, many newer BB30-compatible cranks now feature extra-long spindles for wider compatibility and those will install just fine.\n\n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n The new Cannondale SuperX uses the brands BB30-83 Ai standard Robert Smith \/ Immediate Media\n\n\nCannondale also introduced another bottom bracket standard in the form of BB30-83 Ai.\n\nFirst used on the brand\u2019s SuperX \u2018cross bike, the standard works in exactly the same way as BB30A, but sees the shell ballooned out to 83mm wide, improving tyre clearance and, supposedly, stiffness.\n
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                    • Pros: Lighter weight; more resistant to axle twist; more heel clearance; larger-diameter shell and spindle; potential for narrower pedal stance width\n
                    • Cons: Metal-on-metal interfaces can be prone to creaking; requires a separate bearing puller and press for service; requires high manufacturing tolerances; bearing seats can\u2019t easily be faced post-manufacturing; not all BB30 cranks will fit\n
                    • Crank designs that will fit: BB30 (some), BB386 EVO, standard 24mm external-type, BBRight\n\nPF30 and OSBB\u00a0bottom brackets\nSRAM addressed BB30\u2019s stringent dimensional tolerances and associated manufacturing costs with the advent of PressFit 30 in 2009. Just as with PF86\/92, PF30 is analogous to BB30 in that the bearings and bearing locations are identical, but with the addition of intermediary composite cups that allow for looser frame tolerances.\nNot surprisingly, then, PF30 has gained widespread traction in the industry, particularly with smaller manufacturers who can\u2019t afford high reject rates.\nSpecialized uses PF30 for its high-end mountain bike, confusingly also calling it OSBB though it is a different standard to the OSBB standard found on its road bike.\n\u201cI think it\u2019s more about the simplicity of the manufacturing process,\u201d says Drew Guldalian of Pennsylvania-based custom builder Engin Cycles. \u201cBoring out a [standard] BB30 is not impossible, but in my opinion it\u2019s an unrealistic task from a manufacturer\u2019s standpoint that needs to do something to make money.\n\u201cWith the PressFit 30, they\u2019re using the same technology with the larger bearings and the same technology with the bearings living inside the frame, but they\u2019re utilizing the nylon to their advantage where you have a more realistic tolerance.\u201d\n\u201cPressFit 30 fundamentally provides all the most significant advantages of BB30 but requires much less precise machining of the bottom bracket shell area, as the bearings come inserted into plastic cups that are easier to fit into the frame and less delicate than standalone bearing,\u201d adds SRAM drivetrain product manager Chris Hilton. \u201cPF30 bottom brackets also have an integrated sealing system, which helps prolong bearing life.\u201d\nCannondale\u2019s Chris Peck provided BikeRadar with specific details. While BB30\u2019s bearing bore tolerances are 41.96 +0.025\/-0mm (meaning the bore can be slightly oversized but not undersized), PF30\u2019s requirements are 46.00 +0\/-0.05mm \u2013 exactly half as rigorous.\nSpecialized\u2018s OSBB system is nearly identical to BB\/PF30 but with a few key differences, according to the company\u2019s director of advanced research, Chris D\u2019Aluisio.\n
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                      • Interview: SRAM\u2019s Chris Hilton\n\n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n BB30\u2019s larger 30mm-diameter spindle, compared to the standard 24mm size, allows the use of lighter alloy Immediate Media\n\u201cThe 30mm bearing is a good choice when using thinwall aluminium spindles,\u201d he says, \u201cand the narrow bearing stance (relative to outboard bearings) works perfectly with our carbon arm design needing to make the turn into the spindle. The OSBB is basically the same as BB30 but with a little tighter tolerances and a 0.5mm difference in the clip-to-clip dimension. Cranks of both systems are compatible with each other.\u201d\nD\u2019Aluisio even argues that OSBB offers alignment advantages compared with threaded shells:\n\u201cThe tolerances are not too different but the way they\u2019re measured is. They both have the same needs for concentricity and placement relative to the frame. The threads are at a disadvantage in that they need to be machined from both sides and have a hard time sharing a centerline, whereas our OSBB is machined from one side all at once \u2014 and round holes are easy to measure.\u201d\n
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                        • Pros: Same as BB30 but with lower costs, easier assembly, and the potential for additional bearing seals integrated into the cup\/bearing assembly\n
                        • Cons: Standard-width shell; requires a separate cup remover and press for service\n
                        • Crank designs that will fit: BB30, BB386 EVO, standard 24mm external-type, Specialized OSBB, BBRight\n\nPF30A and PF30-83 Ai\u00a0bottom brackets\nThis is essentially the same as the BB30A and BB30-83 Ai Cannondale system described above, except that it uses bearing cups rather than bearings pressed directly into the frame.\n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n The new Cannondale F-Si uses a PF30-83 Ai bottom bracket Jack Luke \/ Immediate Media\nSimilarly, it\u2019s largely based on the PF30 design, though with a 5mm wider, asymmetric bottom bracket shell \u2014 73mm for PF30A and 83mm for PF30-83.\n
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                          • Pros: As for BB30A and BB30-83 Ai\n
                          • Cons:\u00a0Similar to BB30A and BB30-83 Ai, though press-fit design relaxes tolerance requirements\n
                          • Crank designs that will fit:\u00a0BB30 (some), BB386 EVO, standard 24mm external-type, BBRight\n\nBBRight\u00a0bottom brackets\nMost bottom bracket fitments incorporate bearings that are symmetrically positioned about the frame\u2019s centerline. Much like the Cannondale design,\u00a0Cerv\u00e9lo tipped that apple cart in 2010, however, with the introduction of BBRight.\nBBRight shares its 30mm-diameter alloy spindle, cartridge bearings, and driveside bearing location with PF30 \u2014 in fact, the bottom bracket cups are identical to PF30.\nHowever, the non-driveside bearing is pushed outward by 11mm \u2014 the same as conventional threaded, BB90, and PF86 bottom brackets. This makes it something of a hybrid between the two widely accepted systems.\n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n Cerv\u00e9lo introduced the new BBright system on the R5ca, and while it offers some sound engineering advantages, other companies have been slow to adopt it Immediate Media\n\u201cBBRight uses the 11mm space occupied by an external bottom bracket\u2019s