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  1. #1
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    Chris King's new threaded T47 bottom bracket open standard

    Could Chris King´s new bottom bracket end press-fit problems? - BikeRadar

    Now before you all poopers start to cry about yet another new bottom bracket standard, think about it for a minute.

    - It uses existing 30mm crank (and is compatible with 24mm ones through an adapter)
    - It's threaded (infinitely better for the home mechanic and no noises)
    - It has all the advantages of the 30mm standard (size of the bearing, light alu crank,
    - Unlike conventional threaded, a lot of real estate for the frame builder to work with.
    - Would allow cartridge bottom bracket designs, with stiffer lighter axle while still allowing enough room for larger longer lasting bearings (similar to ISIS overdrive).


    I really hope this open T47 standard get´s picked up by the industry. It could be the end of a lot of our BB annoyances.
    Last edited by CS645; 11-14-2015 at 04:13 AM.

  2. #2
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    A friend and I worked on exactly this some time ago but never got around to partner up with anyone to make it happen.

    Chris King's new threaded T47 bottom bracket open standard-img-20150317-wa0003.jpgChris King's new threaded T47 bottom bracket open standard-img-20150603-wa0000.jpg

  3. #3
    Formerly of Kent
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    I hope angular contact bearings become the new industry standard.
    Death from Below.

  4. #4
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    This is the first "standard" that looks promising since BSA

  5. #5
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    Exited about this, I would like to convert my existing pf30 bikes to t47...

    Where to buy the taping tools? and the BBc cups?

    Any more news?

  6. #6
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    Could be expensive to tap that Pf30 frame.

    T47 vs press-fit bottom brackets - BikeRadar USA

    “I do not see taking a current PF30 bike and then machining new threads being a smashing success,” says bike mechanic guru Calvin Jones of Park Tool. “It will take some very expensive tapping systems, not simply new taps used on old handles. Threads in an English bottom bracket shell sold as a tube are cut by a lathe. So for nice threads, you should be using two taps with this conversion: one to make a rough cut and a second follow-up for the final cut to full pitch diameter. One tap that is staged in two diameters might do the job, but piloting these into a smooth shell straight will be tricky.

    “The circumference of the English cups is about 110mm, but these will be about 145mm, meaning a lot more surface contact and hence the force required is higher,” Jones continues. “Tapping is not a simple process. There will be some cases where everything is done by the book and the threads are trash. Your initial PF30 shells (like all shells) vary in hardness, bore sizing, amount of warp, plus issues in materials.”

    Sure, you could theoretically tap threads into this PF30 shell – but you've only got one shot to get it right

    Guldalian says he’ll be equipped to retrofit PF30 titanium frames to T47 – but that it won’t be cheap.

    “In my estimation, I will need to charge $500 to retrofit a titanium frame from PF30 to T47," he says. "It’s still a viable option if someone really want to give new life to a titanium bicycle frame.”

  7. #7
    Plays with tools
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    This is what we should have done from day one!

    Taping aluminum frames could be done by hand and I don't think it's going to be as big of a deal as Calvin thinks it is. The risk is definitely there to trash a frame in unskilled hands. The original proposed pitch was much more coarse than what the standard settled on, the reason it was changed to the fine thread was to make it easier to tap. Retrofitting a titanium frame is going to be a proper PITA and will require some serious equipment.

    Paragon Machine Works and White Ind. are going to make taps and Paragon will make shells for new bikes. White and King are going to make BB's and I've heard rumors of other companies. Most are going to wait to see where the demand settles out though.

    I hope this catches on in the industry! I think a lot of the small builders are going to jump on board. I could see the boutique mountain brands switch to this as well. Thinking of companies like Santa Cruz, Ibis, Turner and similar. However the truley big bike companies are focused on price and a press fit system is cheaper to make. It will take a lot of crying from dealers and customers to get them to switch.

    We have been talking to many of the people involved in this to square away tool patterns for the cups themselves. We will make professional quality tools to support the system.

  8. #8
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    In my view T47BB is just another attempt of some manufacturers to change BB specs according to their own preferences while disregarding the interests of other manufacturers. Again, there are promises and arguments that seem tempting at first glance. However, if you take a closer look there is little left: 



    (1) The no more creaking promise is questionable: When introducing BB30 or PF30, not only the frame / bearing (cup) interface was changed but equally the bearing (inner race) / spindle interface: While the common BSA outboard cup BBs feature plastic sleeves between the inner bearing race and the spindle, most BB30 or PF30 systems do not. So as the two interfaces have been changed at the same time, why is all the blame on the frame / bearing (cup) interface? Whether reducing the likelihood of unwanted noise really requires the return of the threads is yet to be investigated.

    

(2) The We-need-threads-but-unfortunately-cannot-stick-to-BSA argumentation is also not convincing:

    

They say with BSA, your cannot run (short spindle) BB30 cranksets. Actually that is true, but as meanwhile there is quite a selection of long 30-mm-spindle cranksets out there (including BB offerings for any BB shell but Trek's BB90/BB95): So is compatibility with (short spindle) BB30 cranksets alone enough of an argument for yet another BB specification? 



    BSA paired with long 30-mm-spindles requires small bearings, they say. Really? Take a look at the outboard bearing cups designed for BSA shells and 30-mm-spindles.Typically, these cups house 30/42 x 7 mm (or 6806) ball bearings – not by chance exactly the size you'll find in any BB30 or PF30 system. And basically in the T47BB as well. So forget about the bearing size argument – it is simply not true.



    Yes, but BSA shells do not provide enough space to carbon frame builders in respect of large diameter downtubes etc., they say. Hmm, I still own a 2005 Scott Scale frame with a bulky BB shell area - housing aluminium inserts that have BSA threads. So obviously outer shape and inner diameter are not necessarily linked if we're talking carbon frames. Another invalid argument.



    (3) Further, no one has yet explained to me why an industry not capable of manufacturing plain PF30 BB sleeves according to tight tolerances should be able to bond/mold-in threaded metal inserts into carbon frames in a way that persistently withstands high torque when tightening threaded BB cups.

 Actually, these threaded bonded/molded-in metal inserts have caused long term durability issues in the past – loose BB sleeves were a common issue with early Scott Scale frames, e.g. So as far as carbon frames are concerned, T47BB is certainly not the big bang as it raises new (old) issues. Why change the specs just for the purpose of swapping one potential issue for another?



    Conclusion: 

The inventors of T47BB should better have focused on improvements within the existing specs (there already is plenty to choose from). Which, however, is more difficult to transform into headlines and news releases. And that's where IMHO the motivation is coming from regarding almost all of these brillant BB spec „improvements“: grab attention. As a customer, I fail to appreciate this kind of creativity, not limited to but including T47BB.

  9. #9
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    I see this being in the realm of custom builders.
    Wanted, SRAM GX 2x11 rear derailleur

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  10. #10
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    Quote Originally Posted by Markus B. View Post
    In my view T47BB is just another attempt of some manufacturers to change BB specs according to their own preferences while disregarding the interests of other manufacturers. Again, there are promises and arguments that seem tempting at first glance. However, if you take a closer look there is little left: 



    (1) The no more creaking promise is questionable: When introducing BB30 or PF30, not only the frame / bearing (cup) interface was changed but equally the bearing (inner race) / spindle interface: While the common BSA outboard cup BBs feature plastic sleeves between the inner bearing race and the spindle, most BB30 or PF30 systems do not. So as the two interfaces have been changed at the same time, why is all the blame on the frame / bearing (cup) interface? Whether reducing the likelihood of unwanted noise really requires the return of the threads is yet to be investigated.

    

(2) The We-need-threads-but-unfortunately-cannot-stick-to-BSA argumentation is also not convincing:

    

They say with BSA, your cannot run (short spindle) BB30 cranksets. Actually that is true, but as meanwhile there is quite a selection of long 30-mm-spindle cranksets out there (including BB offerings for any BB shell but Trek's BB90/BB95): So is compatibility with (short spindle) BB30 cranksets alone enough of an argument for yet another BB specification? 



    BSA paired with long 30-mm-spindles requires small bearings, they say. Really? Take a look at the outboard bearing cups designed for BSA shells and 30-mm-spindles.Typically, these cups house 30/42 x 7 mm (or 6806) ball bearings – not by chance exactly the size you'll find in any BB30 or PF30 system. And basically in the T47BB as well. So forget about the bearing size argument – it is simply not true.



    Yes, but BSA shells do not provide enough space to carbon frame builders in respect of large diameter downtubes etc., they say. Hmm, I still own a 2005 Scott Scale frame with a bulky BB shell area - housing aluminium inserts that have BSA threads. So obviously outer shape and inner diameter are not necessarily linked if we're talking carbon frames. Another invalid argument.



    (3) Further, no one has yet explained to me why an industry not capable of manufacturing plain PF30 BB sleeves according to tight tolerances should be able to bond/mold-in threaded metal inserts into carbon frames in a way that persistently withstands high torque when tightening threaded BB cups.

 Actually, these threaded bonded/molded-in metal inserts have caused long term durability issues in the past – loose BB sleeves were a common issue with early Scott Scale frames, e.g. So as far as carbon frames are concerned, T47BB is certainly not the big bang as it raises new (old) issues. Why change the specs just for the purpose of swapping one potential issue for another?



    Conclusion: 

The inventors of T47BB should better have focused on improvements within the existing specs (there already is plenty to choose from). Which, however, is more difficult to transform into headlines and news releases. And that's where IMHO the motivation is coming from regarding almost all of these brillant BB spec „improvements“: grab attention. As a customer, I fail to appreciate this kind of creativity, not limited to but including T47BB.


    1-Sram was one of the first introducers and most used PF30 to short 30mm axle....and their sleeve its made of plastic. Ive seen several of this bb cricking around, I'm sure the problem its not the material as it is the interaction of two peces (bb cups - frame shell) with no propper fixation.

    2- As you say in the frist frase, no posibility of bsa - 30mm short spindle....30mm long spindle are not the way to go, not as rigid or as light as the short ones.

  11. #11
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    Quote Originally Posted by raidm2 View Post
    1-Sram was one of the first introducers and most used PF30 to short 30mm axle....and their sleeve its made of plastic. Ive seen several of this bb cricking around, I'm sure the problem its not the material as it is the interaction of two peces (bb cups - frame shell) with no propper fixation.
    The Sram PF30 bottom brackets I have seen did not have plastic sleeves between inner bearing race and spindle.* There is an aluminium spindle in a steel ring (more or less tighly pressed-in) and when the whole setup starts creaking everybody presumes it must be the plastic cups in the frame – I do not get that.

    *) See (note the bearing specs: the ID is 30 mm): https://www.sram.com/truvativ/produc...bottom-bracket

    Quote Originally Posted by raidm2 View Post
    2- As you say in the frist frase, no posibility of bsa - 30mm short spindle....30mm long spindle are not the way to go, not as rigid or as light as the short ones.
    Whether a (short spindle) BB30 crankset in a BB30/PF30/T47 shell is stiffer than a (long spindle) BB386evo (etc) crankset with outboard bearing cups in a BSA shell, is yet to be investigated. (I tend to think the wider bearings of the outboard BSA cups will make the difference. In any case only Greipel should notice a difference.)

    Regarding weight, the few grams added by additional 18 Milimeters of aluminium spindle are compensated through the fact that the arms require less curvature. The net weight gain (if any) is minimal. However if you do care about weight then you should rather be concerned of the additional metal inserts required to make T47BB work in a carbon frame.

    ----------

    Regardless of all these details my key point is:

    While I do see the particular advantages of almost any of the many BB shell specs out there, I question whether all these marginal improvements warrant new (non standard) specs. Having a true standard is a strong benefit for itself, and anyone intending to (further) demolish an established standard should rather have a really brillant solution (in all relevant aspects, not just a few like T47) or shut up.

    There is two realistic expectations regarding the future prospects of T47: Either silently disappear or cannibalize BSA. For commercial as well as technical reasons, T47 has no potential to substitute the PF30 family.

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