# BB30 and DA7900 Crank Questions (with Photos)



## toddious (Dec 14, 2011)

I just purchased a new Kuota KOM Evo frameset that uses a BB30 bottom bracket. 









I purchased on eBay and the frameset was listed to include BB (doesn't say what type, etc). 
This is a photo of the bottom bracket, which has a Shimano SM-BB-91-42 :









I also purchased a full Dura Ace 7900 group:









Which included a Dura Ace SM-BB 7700 BC 1.37/24T Bottom Bracket and 7900 crank:










Will I be able to make the Dura Ace 7900 crank and BB work with this frame? I don't know a lot about Bottom Brackets and the various sizing, etc. I have heard that Shimano doesn't make anything for BB30, however, the Kuota photos clearly show a BB30 with some sort of Shimano component installed (I believe a press-in BB)?

Will I need to buy an adapter? If so, what type? 

Any help is greatly appreciated. I have about 10 days until the frame and components will arrive, and I'm hoping to get everything necessary to complete the build up before then. Thanks in advance!


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## j.o.e.l (Oct 7, 2009)

You need something like the Wheels Manufacturing BB30 adapter. You won't need the shimano bottom bracket. You'll use the BB30 bearings with these adapters.

http://wheelsmfg.com/bb-30-shims-shimano.html


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## toddious (Dec 14, 2011)

So do I essentially have 2 bottom brackets now? The one in the frame (what is that?) and the one that came with the DA group?

And neither of them will work to make the frame and crank work together?

I hate BB's......


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## cxwrench (Nov 9, 2004)

j.o.e.l said:


> You need something like the Wheels Manufacturing BB30 adapter. You won't need the shimano bottom bracket. You'll use the BB30 bearings with these adapters.
> 
> Wheels Manufacturing BB30-SHIM


if his frame actually had BB30 bearings installed you'd be right. but, as we can clearly see in his photo, it does not. the OP should be able to install his crank directly in to the bb that is in the frame now. i'm actually surprised he hasn't tried.

the threaded bb cups he bought will not be needed at all.

to add to my comment, the OP should measure the width of the bb that is currently in the frame. if it's 90-91mm he's good. put the crank in and go ride. if it's 68mm he'll need some adapters and actual BB30 bearings. but it looks like the correct bb is already in the frame...that's a shimano PF bb. put the crank in and see what happens.


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## looigi (Nov 24, 2010)

Right. Looks like the appropriate adapter/BB is already installed. What may be missing is the appropriate spacers/washers to go with the adapter. 

And yes, the DA BB will not fit that frame.


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## j.o.e.l (Oct 7, 2009)

Cxwrench is correct. I didn't look close enough at the photo. Just stick the crank in and you should be good to go.


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## toddious (Dec 14, 2011)

I have not received the frame or group yet, I'm just asking to make sure I have everything to complete the build when they do arrive. 

So what is the bottom bracket/adapter that's currently installed? Would I be better off installing an adapter and using the Dura Ace bottom bracket that came with the group?


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## JacksonDodge (Mar 26, 2006)

toddious said:


> I have not received the frame or group yet, I'm just asking to make sure I have everything to complete the build when they do arrive.
> 
> So what is the bottom bracket/adapter that's currently installed? Would I be better off installing an adapter and using the Dura Ace bottom bracket that came with the group?


The BB that is currently installed is a Shimano PressFit30 BB. (SM-BB91-42)

It's designed to allow the installation of 24mm spindle Shimano cranks on frames with PF30/BB30 BB shells.


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## cxwrench (Nov 9, 2004)

toddious said:


> I have not received the frame or group yet, I'm just asking to make sure I have everything to complete the build when they do arrive.
> 
> So what is the bottom bracket/adapter that's currently installed? Would I be better off installing an adapter and using the Dura Ace bottom bracket that came with the group?


no, just use what's already in the frame.


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## toddious (Dec 14, 2011)

I'm getting a "tick" in the pedal stroke, and the LBS thinks it may be something happening in the bottom bracket. I'm not sure that I agree. THere is a noticeable "slip" or "tick" (not sure how else to describe it) that you feel when applying pressure on the pedals. It will happen in a rhythm, but not always in the same spot in the pedal stroke. I'm more apt to think it may be chain related as it's not always in the same spot in the pedal motion. 

However, I was considering taking out the Shimano PF30 thats installed, and putting in either an FSA or Wheels Mfg adapter BB30 adapter. Would I then just install the 7900 crank directly through that adapter? So is their no scenario where my DA7900 crank is necessary? 

So are the BB30 bearings then installed directly in the frame? Could those be the issue?

Thanks,


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## Kerry Irons (Feb 25, 2002)

*Chain?*



toddious said:


> I'm more apt to think it may be chain related as it's not always in the same spot in the pedal motion,


If it was a single noisy link in the chain, then it's frequency would change depending on which chainring you're on. As an example, a lot of chains are sized at 106 links (53 inches) and if you're using a 53 large chain ring and have one noisy link, you would get a click every other pedal revolution. If you were on the 39 then it would be every 2.7 revolutions. But if it is the chain you could eliminate the noise with a proper clean/lube.


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## toddious (Dec 14, 2011)

I've heard not to use non 7900 chains on the 7900 crank and cassette. For purposes of testing if the chain is causing this "tick", it wouldn't hurt to slap another chain on for a quick test ride would it?


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## cxwrench (Nov 9, 2004)

toddious said:


> I'm getting a "tick" in the pedal stroke, and the LBS thinks it may be something happening in the bottom bracket. I'm not sure that I agree. THere is a noticeable "slip" or "tick" (not sure how else to describe it) that you feel when applying pressure on the pedals. It will happen in a rhythm, but not always in the same spot in the pedal stroke. I'm more apt to think it may be chain related as it's not always in the same spot in the pedal motion.
> 
> However, I was considering taking out the Shimano PF30 thats installed, and putting in either an FSA or Wheels Mfg adapter BB30 adapter. Would I then just install the 7900 crank directly through that adapter? So is their no scenario where my DA7900 crank is necessary?
> 
> ...


you can't do that. you have a PF frame. there is nothing about BB30 that will work w/ your frame. it's just carbon into which the PF cups are pressed. you need to understand the difference between BB30 and PF-whatever. if it's a BB30 frame, the inside of the bb shell will be aluminum. there are 2 grooves machined into the shell for the spring clips that locate the BB30 bearings. your frame does not work like this. it's just carbon...the PF BB cups are pressed directly into the carbon. 
you DO NOT HAVE BB30 bearings. you have PF cups w/ Shimano compatible bearings (24mm ID) pressed into the cups. if you're experiencing a noise that isn't at the same spot every pedal revolution, it's not the bottom bracket. 



toddious said:


> I've heard not to use non 7900 chains on the 7900 crank and cassette. For purposes of testing if the chain is causing this "tick", it wouldn't hurt to slap another chain on for a quick test ride would it?


you can use any 10 speed chain you want. obviously shimano thinks the 6700/7900 chains work best, and they actually do. but...any, and i mean ANY 10 speed chain will work.


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## AtomicMoose (Aug 15, 2012)

Todd, for your reference, this is BB30:


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## toddious (Dec 14, 2011)

cxwrench said:


> you can't do that. you have a PF frame. there is nothing about BB30 that will work w/ your frame. it's just carbon into which the PF cups are pressed. you need to understand the difference between BB30 and PF-whatever. if it's a BB30 frame, the inside of the bb shell will be aluminum. there are 2 grooves machined into the shell for the spring clips that locate the BB30 bearings. your frame does not work like this. it's just carbon...the PF BB cups are pressed directly into the carbon.
> you DO NOT HAVE BB30 bearings. you have PF cups w/ Shimano compatible bearings (24mm ID) pressed into the cups. if you're experiencing a noise that isn't at the same spot every pedal revolution, it's not the bottom bracket.
> 
> 
> ...


I believe my frame is BB30 correct? It just already has a Shimano Press-Fit installed in it when I bought it. I'm considering removing this, and pressing in an FSA BB30 adapter instead (which then makes it standard threaded BB), and then using my other DA7900 BB and cups that came with my group. Does that make sense? 

I agree that I don't think the problem is the bottom bracket, given the symptoms, but I know more about the condition of the group then I do the PF adapter that's currently installed, so I'd rather just install the 7900 BB. 



AtomicMoose said:


> Todd, for your reference, this is BB30:


Thank you. So that is a BB30 frame with the BB30 bearings already installed? So with that setup, would you just directly install a BB30 crank? 

I've also considered swapping out the 7900 crank for a true BB30 crank. If I did this, I would remove the PF adapter, and need to purchase a new crank along with BB30 bearings?


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## AtomicMoose (Aug 15, 2012)

toddious said:


> Thank you. So that is a BB30 frame with the BB30 bearings already installed? So with that setup, would you just directly install a BB30 crank?


That is correct. my FSA crank installs directly into those bearings.



toddious said:


> I've also considered swapping out the 7900 crank for a true BB30 crank. If I did this, I would remove the PF adapter, and need to purchase a new crank along with BB30 bearings?


I'm not super knowledgeable on BB technology, but by what cxwrench mentions, he doesn't think your frame is a BB30. TBH, it doesn't look like one to me either. 

Perhaps this will help shed some light on your questions?
Tech FAQ: The Low Down on Bottom Brackets


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## toddious (Dec 14, 2011)

AtomicMoose said:


> That is correct. my FSA crank installs directly into those bearings.
> 
> I'm not super knowledgeable on BB technology, but by what cxwrench mentions, he doesn't think your frame is a BB30. TBH, it doesn't look like one to me either.
> 
> ...


It says "BB30 Integral Carbon Technology" right on the bottom bracket, so I'm fairly sure that the frame is BB30. Why else would there be a Press-Fit adapter installed? The bike normally comes with a proprietary K30 Kuota BB30 crank. 

The way the PF adapter works, also, I think there is already supposed to be BB bearing installed in the frame before the PF adapter is installed, so in theory if I remove the PF adapter, I should just be able to install a BB30 crank directly. No?


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## AtomicMoose (Aug 15, 2012)

toddious said:


> It says "BB30 Integral Carbon Technology" right on the bottom bracket, so I'm fairly sure that the frame is BB30. Why else would there be a Press-Fit adapter installed? The bike normally comes with a proprietary K30 Kuota BB30 crank.


I did go back and look at the pictures, and I see the "BB30" stamp on there. Clearly, some adapter is installed. 



toddious said:


> The way the PF adapter works, also, I think there is already supposed to be BB bearing installed in the frame before the PF adapter is installed, so in theory if I remove the PF adapter, I should just be able to install a BB30 crank directly. No?


Sounds reasonable to me. But I'll defer to someone more experienced on this one.

Which crank did you have installed the other day when you crashed it? (BTW, how you feeling?)


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## AtomicMoose (Aug 15, 2012)

Ok, found some more info on this BB91 adapter you have:
Weight Weenies • View topic - Specialized - Shimano BB91

So if I am following the logic correctly, you should be able to remove them and have BB30 bearings in there.

However, the DA cranks are not BB30, so obviously you'd need to get something compatible.


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## toddious (Dec 14, 2011)

AtomicMoose said:


> I did go back and look at the pictures, and I see the "BB30" stamp on there. Clearly, some adapter is installed.
> 
> Sounds reasonable to me. But I'll defer to someone more experienced on this one.
> 
> Which crank did you have installed the other day when you crashed it? (BTW, how you feeling?)


I had the DA7900 crank installed, using the previously installed Shimano PF adapter that was in the frame when I got it. Like I said, I also have a DA7900 bottom bracket/cups that I could install instead of the PF adapter, but I would need another adapter (like the FSA BB30 adapter: http://www.jensonusa.com/!f6fX3!5bg93gmBYgY2fjow!/FSA-Press-In-Adaptor-For-BB30) to make it work either way. 

I'm still a little bit up from the crash. Road rash has a hard time scabbing/healing on my shoulder because it moves around so much I'm constantly stretching it. Have a pretty solid bruise on my hip as well.... I'm hoping I recover quickly because I"m riding the MS150 next weekend!



AtomicMoose said:


> Ok, found some more info on this BB91 adapter you have:
> Weight Weenies • View topic - Specialized - Shimano BB91
> 
> So if I am following the logic correctly, you should be able to remove them and have BB30 bearings in there.
> ...


Ok, thats pretty much what I thought. 

Let me ask this. What exactly is the "Bottom Bracket" itself? Is it the housing? It is the bearings? Is it the combination of bearings/cups in an external-threaded setup? 

So I have a BB30 frame, and it already has bearing installed, and then I could put in a crank directly (that is BB30)- does that make the bearings the "Bottom Bracket" in that situation?


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## AtomicMoose (Aug 15, 2012)

toddious said:


> I had the DA7900 crank installed, using the previously installed Shimano PF adapter that was in the frame when I got it. Like I said, I also have a DA7900 bottom bracket/cups that I could install instead of the PF adapter, but I would need another adapter (like the FSA BB30 adapter: FSA Press-In Adaptor For BB30 > Components > Small and Service Parts | Jenson USA Online Bike Shop) to make it work either way.


Ok, yeah... this is what I figured. I really hate adapters. Its just more things to maintenance/fail/break...



toddious said:


> I'm still a little bit up from the crash. Road rash has a hard time scabbing/healing on my shoulder because it moves around so much I'm constantly stretching it. Have a pretty solid bruise on my hip as well.... I'm hoping I recover quickly because I"m riding the MS150 next weekend!


I crashed in July and had a huge!! patch of road rash on my hip. I'm still scarred from it. And hold up, where are you from? I'm riding the MS150 (single day) next week as well! The one that leaves from Woodcrest Station. Maybe I'll see you out there!



toddious said:


> Ok, thats pretty much what I thought.
> 
> Let me ask this. What exactly is the "Bottom Bracket" itself? Is it the housing? It is the bearings? Is it the combination of bearings/cups in an external-threaded setup?


My understanding of this (someone please correct me if I am wrong) is that the BB is the 'system' by which the cranks are installed. So for the purpose of this discussion, I'd say is the BB shell (frame) and the bearings, snap rings, etc.



toddious said:


> So I have a BB30 frame, and it already has bearing installed, and then I could put in a crank directly (that is BB30)- does that make the bearings the "Bottom Bracket" in that situation?


I'd say yes.


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## toddious (Dec 14, 2011)

AtomicMoose said:


> I crashed in July and had a huge!! patch of road rash on my hip. I'm still scarred from it. And hold up, where are you from? I'm riding the MS150 (single day) next week as well! The one that leaves from Woodcrest Station. Maybe I'll see you out there!


I'm in Orlando FL, and will be riding in the "Cycle The Shore" MS150 from St. Augustine to Daytona (and back). Best of luck to you in the Woodcrest Ride!

I'm definitely anticipating having a scar for a while...


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## AtomicMoose (Aug 15, 2012)

toddious said:


> I'm in Orlando FL, and will be riding in the "Cycle The Shore" MS150 from St. Augustine to Daytona (and back). Best of luck to you in the Woodcrest Ride!
> 
> I'm definitely anticipating having a scar for a while...


I didn't think I remembered reading anywhere that you were local (NJ). Will you have your new Kuota back in time for the ride?

Best of luck to you as well! :thumbsup:


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## toddious (Dec 14, 2011)

AtomicMoose said:


> I didn't think I remembered reading anywhere that you were local (NJ). Will you have your new Kuota back in time for the ride?
> 
> Best of luck to you as well! :thumbsup:


I'm hoping I'll have it back! I'm gonna call the guy today to get an update. It wouldn't be nearly as fun riding a loaner/rental bike for 150 miles!


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## cxwrench (Nov 9, 2004)

OP, i think you're right. it looks like your frame is BB30, but it currently has a PF91 bottom bracket unit installed. you should be able to take it out, and install either:
the BB30 to threaded adapter you were talking about earlier, OR...
press in BB30 bearings and use an adapter that slides into the bearings to let you use your Shimano crank. this is the much-less-permanent method. if you press in the FSA or SRAM adapter, it's not recommended that you ever try to remove it. this could be a problem if you ever want to sell the frame or go back to a BB30-style crank in the future.
i'd recommend to go w/ the BB30 bearings and the Problem Solvers adapters...








also, there are 'bottom brackets' that are bearing units...these get installed into the 'bottom bracket' area of the frame. hope that clears up your confusion.

oh yeah...you don't have an 'adapter' installed right not, that's actually a Shimano PF bottom bracket unit pressed into your frame. i'm not sure why you want to go to all this work to basically end up w/ the same thing you have now. you seem hell-bent on using the Shimano threaded bottom bracket you have for now real reason. i'd just leave it as is and work on getting rid of the noise. if you want to change cranks in the future (not sure why you'd want to do that, but it's your choice), then worry about which BB you need.


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## toddious (Dec 14, 2011)

cxwrench said:


> OP, i think you're right. it looks like your frame is BB30, but it currently has a PF91 bottom bracket unit installed. you should be able to take it out, and install either:
> the BB30 to threaded adapter you were talking about earlier, OR...
> press in BB30 bearings and use an adapter that slides into the bearings to let you use your Shimano crank. this is the much-less-permanent method. if you press in the FSA or SRAM adapter, it's not recommended that you ever try to remove it. this could be a problem if you ever want to sell the frame or go back to a BB30-style crank in the future.
> i'd recommend to go w/ the BB30 bearings and the Problem Solvers adapters...
> ...


Thanks, that helps me to understand the benefits/drawbacks of the two different adapter approaches. I think I would lean towards the Wheels Manufacturing solution (same as the image you posted) and utilize the internal BB30 bearings, and give myself the option to swap out for BB30 down the road. 

What exactly does the SHimano PF adapter do then? If it's still utilizing the BB30 bearings, is it really only sizing down the bearings to the standard english size(no bearings in the PF adapter itself correct)? Whats the difference between the Shimano PF vs. the BB30 adapter that you have posted (ex: Wheels Mfg)?


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## cxwrench (Nov 9, 2004)

toddious said:


> Thanks, that helps me to understand the benefits/drawbacks of the two different adapter approaches. I think I would lean towards the Wheels Manufacturing solution (same as the image you posted) and utilize the internal BB30 bearings, and give myself the option to swap out for BB30 down the road.
> 
> What exactly does the SHimano PF adapter do then? If it's still utilizing the BB30 bearings, is it really only sizing down the bearings to the standard english size(no bearings in the PF adapter itself correct)? Whats the difference between the Shimano PF vs. the BB30 adapter that you have posted (ex: Wheels Mfg)?


read my last post again. you don't have a PF 'adapter', *you have a PF bottom bracket*. it's 2 plastic cups w/ appropriate sized bearings (NOT BB30) for a Shimano crank spindle. that spindle is 24mm in diameter, not 30mm as a BB30 spindle would be.
BB30 bearings press directly into the frame. no cups. they are generally 42mm o.d., and you guessed it...30mm i.d.
the BB30 adapters i posted the photo of press into BB30 bearings and sleeve them down to 24mm...the Shimano spindle diameter. the Shimano PF bb you have doesn't need adapters because it's designed to work w/ a Shimano crank. the PF bb IS bearings...the adapters pictured press into bearings. get it?
this is why i'm wondering why you're so convinced you need to spend money to replace something that already works. if you really want to get rid of the money, send it to me. i need some new cx tires.


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