I'm considering purchasing a carbon thru-axle road bike frame.
It has a BB68 bottom bracket.
From my limited knowledge it seems that it only supports mountain bike type cranksets.
Would a BB68 frame support Shimano Ultegra, SRAM Force, FSA K-force light type road cranksets?

What bike do you have? I've never heard of BB68.

68mm threaded (aka BSA) is a very common threaded standard.
BB86 is a less common standard.

Thanks for the reply gsa103.
The carbon frame I'm looking at buying is described as "BB:BB68"
I've attached an image of the specs from the website.

If you mean BB86, yes, it's designed to work with various 24mm spindle road cranksets that would otherwise use outboard bearings that are threaded into a 68mm English threaded shell. Hollowtech II, GXP, etc, are examples. The mtb version of this type of bb, for 24mm spindle mtb cranks, is BB91/92 (everything's the same except the bb shell/bb sleeve is approx. 5mm wider than a BB86 shell).

in advance? if you can get something else it may be better in the long run.

(complete bike saves money over frame & parts bought separate)

As I've noted; Newer external bearings that screw in begat re-designs having the frame widened
to make the bearings
Internal flush to outside of frame, again ..

threaded externals are quick & easy to replace .. an advantage, IMO.






./.

Chinese carbon frame? You'll have to contact the manufacturer directly to see if they mean a threaded BSA or a press-fit BB86, either is a possibility.

The other option is to just buy the frame, then buy the appropriate crank/BB you have frame in hand and can measure yourself.

Thank you all for your replies.
Much appreciated.
I contacted the manufacturer as gsa103 suggested.
The BB is a press-fit BB86

I received my carbon road frame yesterday.
I've taken a few pics of the BB shell.
It's threaded.
Can someone help me determine what type of BB I should buy?
Thanks!

take the frame to a LBS otherwise your going for best guess also modern bb's are measured in metric

Take it to a bike shop or get a good caliper and re-measure. All BB are measured in mm. Printing out a ruler on a sheet of paper is absolute NOT good enough to use in this situation.

Looking at your pictures posted, I have no idea what it is.

Width (you show ~2.625in = 66.7mm). Maybe that's 68mm, hard to tell without a better measurement?
ID of the BB shell (~1.25in = 31.75mm) Seems small for BSA, but bad measurement...

Since it's threaded chances are it's just a standard BSA bottom bracket, you need to pick the correct one for your crankset.
Bottom Bracket Standards | Park Tool

If the bottom bracket is 68 mm across and the threaded openings are 34.8 mm, then it's almost certainly a common English threaded bottom bracket.

To reiterate: BB68 is Chinglish for the old standard "weld it up" BB shell right to left width of 68mm. This contrasts with ATB BB shells which are 73mm wide.
These BB are threaded. CF frames allowed a new standard with bearings pressfit into the frame and NO threading needed. One such was BB86 with a minor
variant styled BB90. The BB86 and BB90 are trademarked names with sets of engineering drawings specifying them exactly.

"BB68" as noted is not trademarked and simply refers to the bottom bracket shell width. The vast majority are threaded internally but a few iconoclasts made
bikes without internal threading in decades past. Early CF frames incorporated a threaded metal bottom bracket shell (68mm wide) into the CF, but most are
now made with enlarged bottom bracket volumes for rigidity and to take advantage of the change over in cranks from sub 1" diameter axles to 1" or larger diameter axles with the axle integral with the crank and bearings moved into the frame.

A huge thank you for all your replies.
I will bring the frame to my LBS to determine the BB I have.

If it is threaded 68-mm (BSA) you can use Shimano Hollowtech BB which are probably my favorite of all the different BBs out there (never had a T47, though.)