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In concept, at least, all of the standards we’ve covered are functionally sound. But the realities of relaxing tolerances can create other issues. Len Phipps, owner of frame number KA996, which dates from early 1950 sent in a detailed drawing of the intricate lug-work, referring to it as an “Apollo” model. At this early date it could have been an example of a customer’s personal specification; in the absence of any available catalogue references to the Apollo model, it must remain as being a special build option that the company chose not to advertise widely.
Because you are moving from an inboard bearing setup to an outboard bearing system you also need to clean or “dress” the BB shell’s face.
T47 bottom brackets
Here is one theory from BB Infinite including a very comprehensive summary. They cover the conventional wisdom on what to do about this as well as providing novel insight. Other notes Asymmetric BB shell which is wider on non-driveside. Wider overall shell is also claimed to improve bearing support PF30 The need for a heavier metal interface looked like a limiting factor for mass-produced carbon bikes, but with a manufacturer like Trek on now on board (as mentioned above, its 2020 Domane features a T47 BB) that could all be about to change. In the photo you see hoses at the bottom, adapter fittings in the middle and torch bases at the top. Very closely related to Trek’s BB90/BB95 system is the BB86/BB92 standard used by Scott, Giant, Pivot, and many others.
With the PressFit 30, they’re using the same technology with the larger bearings and the same technology with the bearings living inside the frame, but they’re utilizing the nylon to their advantage where you have a more realistic tolerance.” There’s only around 0.025mm of tolerance to work with; the slightest mistake can mean a ruined frame.The whole shebang, 3-in-1 Integrated BB Reducer, has got you covered for surely every contingency, should you need it. KD10 – KD69 – KD98 – KD100 – KD177 – KD213 – KD444 – KD472 – KD566 – KD573 – KD586 – KD650 – KD758 – KD909 There are adequate post-war verified numbers to be able to date frames quite accurately. After the war the company started to use a numbering system that started with the prefix letter “K”, followed by numbers, which did not go beyond 999. There are no records yet of four figure numbers following the letter prefix. Once the numbers reached 999 the company went on to use the prefix “KA”, followed in sequence over the years by “KB, KC, KD, KE”. There are no known recorded letter combinations beyond “KE”.
That 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’ll 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’t work. This 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). I’d fit a stem 10-15mm longer if it were mine; it would still be short enough to keep a tight rein on the steering. Other notes Matches the wide bearing spacing of a BSA external BB with a large 30mm spindle BB392EVO The tolerances are not too different but the way they’re 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 — and round holes are easy to measure.”Pros: Vast crankset compatibility, open standard, threaded design easy to service and prevent from creaking, same dimensions as PF30
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