T47 Bottom Brackets Explained

In this quick video, we get down to basics with T47 bottom brackets with the goal of making it easier for you to figure out the right one for your bike.
Please note that because we were trying to make this a fairly broad and simple video, there may be some confusion stemming from the vast and confusing array of standards that T47 attempts to encompass. Below are some definitions that may help:
T47: this refers to a bottom bracket shell with 47 x 1mm threads and the type of bottom bracket that also has those threads. T47 bottom bracket shells come in widths ranging from 68 to 100+mm, and T47 bottom brackets come in both INTERNAL AND EXTERNAL versions. As explained in the video, by choosing the correct type (internal or external) of bottom bracket in combination with the width of you bottom bracket shell, you can use different type of cranksets.
Note that a VERY common point of confusion arises from the term BB30. BB30 was a bottom bracket standard developed by Cannondale, and later used by Specialized and some other companies that uses a 68mm wide, un-threaded bottom bracket shell with 42mm press-in bearings. It's usually very easy to recognize because most BB30 cranksets say "BB30" on the crank spindle. It's NOT a blanket term for all 30mm spindle cranksets (such as Cane Creek or White Industries, to name only a couple). A 68mm wide T47 bottom bracket with INTERNAL cups can accomodate a road BB30 crankset, which is one of the beauties of T47, but it's also one of the things that's so confusing.
AS NOTED IN THE VIDEO, THE MAIN TAKEAWAY HERE IS THAT NOT ALL 30MM SPINDLE CRANKSETS ARE BB30. The video gives a basic breakdown of which type of crank uses which type of T47 bottom bracket, but because of how confusing the nomenclature is around this subject, it's very easy to get confused.
For more details about specific Fit Kits, and a more thorough explanation of the various options, check out our blog post on the same topic: avt.bike/blogs...
Chris King Fit Kit instructions can be found here: cdn.shopify.co...
Get your Chris King Bottom bracket here: avt.bike/colle...
Get your White Industries bottom bracket here: avt.bike/colle...
As always, thanks for watching and let us know if you have any questions!

[@gvnrchmnd]

I have a T47/68 BB shell on a frame I’m building up. Your explanation took the headache out of either needing an inboard or outboard BB so thank you 🙏🏻

[@cesar0610]

Excellent explanation to help understand the complex world of BB's. I'm planning move out of my tree's bikes with BB90 to a more reliable one and T47 is in my bucket list.

[@rattila13]

Cervelo and Factor have BBrignt T47 now, internal on the non-drive side, and external on the drive side also referred to as T47a.

[@BluedotProductions]

Thanks for this. You gave us some good info.

[@marcinbujar1872]

Can you please advise which is better for a titanium frame with Ultegra Di2, BSA threaded BB shell or T47 treaded BB shell? Is it worthy to "upgrade" for T47 BB shell when selecting titanium frame?

[@burkeculligan4756]

T47 is an awesome approach - let's hope all the other variations disappear. Love all my T47's!

[@godfreytan1001]

Thanks well explained.

[@DudesCover]

Can Campagnolo Veloce Crank with 25mm width spindle installed on t47 BB ?

[@AVTBike]

Yes, but you will need a 25mm BB to match. Possibly something from Campy or Ceramicspeed.

[@burrussw]

good information, one question, have bikes been made that require t47 bottom brackets that have 68 or 73 mm shells?

[@AVTBike]

Absolutely. Those frames normally require an External T47 BB.

[@GokkunGuru]

Does SRAM make DUB T47 for 73mm shells? And would that be an external or internal bearing? Thanks

[@patas67]

hi there I am now new to T47 standards, all my bikes has been using bb86 or bb386 pressfit, now I am into a new frame for gravel which use t47, the brand did not specific shield width however ( I am not sure if it is a 68mm or 86mm ) , some BS has a limited stock of BB for dub sram where I live, I will set up a 2x force wide crankset on this frame ( Aurum brand, Manto gravel model), I got the dub road/road wide T47 / 68 , should fit or should not? Or would I need in T47 as mentioned?

[@AVTBike]

Most frames like that would use an external BB. It may be easiest if you can measure the frames BB shell to confirm which size your frame uses.

[@davidfrankel7415]

I've got a T47 30i ceramic bottom bracket with FSA SL-K Modular Super Compact BB386EVO Crankset 165mm 30/47 tooth. I need to replace my T37 30i. What fit kit do I need to purchase? Thanks!

[@AVTBike]

Fit Kit #5 for 30mm spindles.

[@trekmadone3225]

Have a trek madone 7.9 bb90 bottom BRACKET can i use this T47 bottom bracket if ues which one?

[@Bikerdave87]

Please define a T47 BB. How did it get the name ? Personally I will be fitting a RITCHEY Cross Crank to a RITCHEY Logic Roadie. Currently the old school internal is fitted. Kellan will know as he has a Road Logic. AVT my parts shop for a while. Good Vid otherwise. Maybe T47 means external. ?? cheers.

[@AVTBike]

A T47 bottom bracket shell is threaded with a 47 x 1mm thread, and comes in a variety of lengths ranging from 68 to over 100 mm. It's confusing because it can be used with all sorts of different crank standards (including BB30, PF30, DUB, 24mm, 22/24mm stepped GXP, and a variety of other 30mm standards) ALL DEPENDING ON THE WIDTH OF THE T47 SHELL. Finally T47 just refers to the bottom bracket shell and the type of bottom bracket that it takes. But the T47 bottom brackets come in both INTERNAL AND EXTERNAL VERSIONS, as explained in the video. This is one of the reasons that it can be extremely confusing! The video tries to explain all of this in a succinct way, but that doesn't mean that it covers all of the options and it doesn't address all of the possible points of confusion. Does that help answer your question?

[@Bikerdave87]

@@AVTBike thanks.

[@leechristopher6172]

What are the advantages of internal bearings vs external bearings if there is any.

[@AVTBike]

The main difference, is that they are designed for different width BB shells.

[@metalburstaudiofreak7942]

There is a t47 with Italian threads???

[@stefanopassiglia]

When do you need spacers and how are they used?

[@AVTBike]

Spacers are used to adapt BB's/cranks to each specific frame. There are BB cup and crank spindle spacers which can be used to adjust the spindle position to add extra clearance, or to fine tune chainline. Here's some links for Chris King and White Industries recommendations. Chris King cdn.shopify.com/s/files/1/2920/2114/files/bb_fit_guide_r1.pdf?v=1632265266 White Industries MR30 www.whiteind.com/wp-content/uploads/2021/02/White-Industries-MR30-Crank-and-Bottom-Bracket-Compatibility-Chart-V1-Sheet1.pdf

[@torofpv420]

I have a 2021 Trek Domane with a T47 BB. The shell is 73mm. I have a SRAM RED eTap AXS groupset that I plan on installing on it but I just realized the crankset is a GXP which has the 24/22 step. So would I need an Internal or external BB?

[@spencerfisher4080]

24i with a gxp fit kit. if it was dub you would need a 30i with a dub fit kit. always going to be internal on a trek because of the frame

[@gvnrchmnd]

@@spencerfisher4080 In the video he states 68/73 would have outboard BB’s. Why would trek frames be any different out of curiosity?

[@spencerfisher4080]

@@gvnrchmnd Just the way the frames are designed