Do BB30 cranksets fit T47 bottom brackets?

[BRad704]

Looking around online and I can't find a definite "yes" or "no"... Spindles are 30mm on each and the T47 external width is 90-92mm on my Crockett. Right now it has a Praxis aluminum crankset and ring, and I'm thinking about upgrading to something carbon from SRAM.

[aatores]

The T47 BB comes in several different configurations to fit different crank spindles. My 2020 Domane came with a Praxis T47 with Shimano cranks -- so it's meant for a 24mm spindle. You can also get a T47 BB for a GXP spindle or DUB spindle if you're going with a SRAM crankset. I assume you can get a T47 BB for a 30mm spindle as well but I haven't actually seen it. I have an extra T47 GXP BB (made by Wheels Manufacturing) if you decide to got the SRAM GXP route.

[jtbadge]

GXP cranks will fit, but only the "long spindle" BB30 stuff like Force 22/1 and Rival 22/1 BB30 cranks will work. The 10 speed and first gen Red 22 have the short/"true BB30" spindle which won't be long enough for your 86mm BB width.

Either way you'll need different BB cups as the Praxis crank needs a proprietary NDS endcap.

edit: from cyclingtips (https://cyclingtips.com/2019/06/trek-t47-threaded-bottom-brackets/):

"Ahlberg is insistent that Trek’s modified T47 system does not constitute yet another new “standard”, despite the 1mm-narrower shell. Current wide-format, internal-bearing T47 will also work on the new Crockettt, and according to Ahlberg, both Shimano and SRAM have also stated that their cranks will accommodate either existing T47 cups or these modified ones from Praxis; there’s more than enough leeway in the threaded preload collars that SRAM uses, and enough spline length in Shimano’s Hollowtech II spindle."

[Mark McM]

For actual BB30 specific cranks, the answer is no, it won't fit on a Trek Crockett with T47 bb shell. But not all 30mm spindle cranks are BB30 specific - BB30 specific cranks have short spindles, intended to work with the 68mm wide BB30 bottom bracket shell. Other 30mm spindle cranks (such as BB386 cranks) have longer spindles, and can work with the Crockett's 86mm wide BB shell.

SRAM cranks that are labeled "BB30" are not true BB30 specific cranks - they spindles long enough to work on BB386 bottom brackets, and should work on the Crocket (with the right BB cups).

[rheosibal]

Cranksets from Sram = No.
The longer 30mm spindles are only 86.5mm wide. Too narrow for what you need.

I think Raceface, Easton, THM, FSA, Praxis M30, and CaneCreek MTB are your only 30mm spindle crankset options.

[ltwtsculler91]

This all seems confusing to me. I have a SRAM Red BB30 crank on my No22 Reactor which is standard T47.. No reason I can see why it wouldn't work on the Trek

[rheosibal]

That's because your No22 has a standard 68mm shell. OP's is 90-92

[jtbadge]

This all seems confusing to me. I have a SRAM Red BB30 crank on my No22 Reactor which is standard T47.. No reason I can see why it wouldn't work on the Trek

There are a few different versions of T47 out there.

For road applications, originally the shells had either a 68mm or 86.5mm width. The 68mm width is essentially a "true BB30" shell with threads added, so those fit "true BB30" cranks. The 86.5mm shell (and Trek's 85.5mm variant) are much wider and can only fit certain cranks.

Wheels MFG has a breakdown of most of the variants here:

https://wheelsmfg.com/blog/how-to-select-the-correct-t47-bottom-bracket

[FriarQuade]

Just to clear this up, T47 denotes a threaded interface fitment between the bottom bracket and the frame. It can accommodate many different crank to bottom bracket configurations. It does not solely dictate the crank compatibility though. BB30 denotes a Frame/BB/Crank interface that is more restrictive. Many people mistakenly use BB30 to describe any crank with a 30mm spindle which doesn't tell the whole story. To further complicate it, there's multiple version of BB30.

[binouye]

Cranksets from Sram = No.
I think Raceface, Easton, THM, FSA, Praxis M30, and CaneCreek MTB are your only 30mm spindle crankset options.

Actually, Praxis spindles step down from 30 at drive side to 28 at NDS, so they require a propriety Praxis BB even though the spindle is "30mm". I have a Praxis T47 BB and Praxis Zayante M30 crank in a 68mm T47 BB shell.

King makes Shimano, Sram, and 30mm T47 versions. But I tried an Easton 30mm crank in a King 30mm T47 and they weren't compatible, then scored a very cheap Praxis crank and went with the Praxis option.

[kramnnim]

Cranksets from Sram = No.
The longer 30mm spindles are only 86.5mm wide. Too narrow for what you need.

I think Raceface, Easton, THM, FSA, Praxis M30, and CaneCreek MTB are your only 30mm spindle crankset options.

I thought the long spindle SRAM cranks are long enough?

Rotor spindles are...

[rheosibal]

I thought so too - in any shell 86.5 or smaller.

OP is saying his T47ib measures 90-92, so maybe Trek is doing something wonky again.

[Mark McM]

Cranksets from Sram = No.
The longer 30mm spindles are only 86.5mm wide. Too narrow for what you need.

I think Raceface, Easton, THM, FSA, Praxis M30, and CaneCreek MTB are your only 30mm spindle crankset options.

I'm confused. According to this CyclingTips (https://cyclingtips.com/2019/06/trek-t47-threaded-bottom-brackets/) article, the Crocket has a bottom bracket width of 85.5mm and is compatible with 86.5mm spindle cranks. Perhaps the OP just needs different T47 cups to fit SRAM cranks?

[bikinchris]

The first T47 equipped bike I built used a Red BB30 crankset.

[rheosibal]

I'm confused. According to this CyclingTips (https://cyclingtips.com/2019/06/trek-t47-threaded-bottom-brackets/) article, the Crocket has a bottom bracket width of 85.5mm and is compatible with 86.5mm spindle cranks. Perhaps the OP just needs different T47 cups to fit SRAM cranks?

I read that too. Just recommending options based on OP's actual measurements.

[sparky33]

There are a few different versions of T47 out there.

For road applications, originally the shells had either a 68mm or 86.5mm width. The 68mm width is essentially a "true BB30" shell with threads added, so those fit "true BB30" cranks. The 86.5mm shell (and Trek's 85.5mm variant) are much wider and can only fit certain cranks.

Wheels MFG has a breakdown of most of the variants here:

https://wheelsmfg.com/blog/how-to-select-the-correct-t47-bottom-bracket

Thank you for this.

[BRad704]

Wow, this blew up faster than I'm used to...

OK... some measurement clarifications.

The BB SHELL is 86mm wide.
The outer edges of the BB itself is 92mm.
Someone was correct with the Praxis specs of "M30 = 30/28mm spindle".

I think I've got enough information to know what I'll need to buy in order to use a different crankset.

Complicated situation overall, but thank you all for talking through it! :banana:

[sparky33]

That is a really informative article in that link.
It makes a point of saying that there are internal and external versions of T47 bb cups, and that makes all the difference wrt to spindle length compatibility.

For example,
I have a 30mm T47 external bb on a 68mm shell with 30mm Easton EC90
cranks.
I am planning to fit a 30mm T47 internal bb on a 68mm shell with SRAM Red BB30 cranks.


There are a few different versions of T47 out there.

For road applications, originally the shells had either a 68mm or 86.5mm width. The 68mm width is essentially a "true BB30" shell with threads added, so those fit "true BB30" cranks. The 86.5mm shell (and Trek's 85.5mm variant) are much wider and can only fit certain cranks.

Wheels MFG has a breakdown of most of the variants here:

https://wheelsmfg.com/blog/how-to-select-the-correct-t47-bottom-bracket