# BB30 in standard threads?



## SkiLikeMe (Oct 3, 2010)

I am still trying to figure out this whole BB mess... too many standards.

I think I have to scrap my current CAAD 9 frame due to a dent/crack.

Can I use my BB30 Force cranks and BB on any frame with an adaptor? Is there such an adaptor even?

Thanks for the insight!


----------



## PlatyPius (Feb 1, 2009)

BB30 crank is bigger than normal 68mm BST BB. Ergo, no. There is no adaptor to make a smaller BB magically grow into a bigger one.

You can put a regular crank in a BB30 with an adaptor, but you can't go the other way.


----------



## VCRC Bike (Jul 1, 2009)

This might be what you are looking for:

http://www.rotorbikeusa.com/products/bsa_bottom_bracket.html


----------



## PlatyPius (Feb 1, 2009)

VCRC Bike said:


> This might be what you are looking for:
> 
> http://www.rotorbikeusa.com/products/bsa_bottom_bracket.html


Ok, apparently you CAN put a BB30 crank in a standard frame. Would you, however, want to? How thin do those BB bearings have to be? How long would/could they last? Perhaps this is why I have never seen one before...


----------



## Kontact (Apr 1, 2011)

Some 30mm cranks can fit into an English threaded BB, like BB386, but normal BB30s are too narrow - not enough space between the cranks for the bearings and the BB shell.

The Rotor cranks can do it, but those cups will only work on the Rotors - not a SRAM BB30.


----------



## ms6073 (Jul 7, 2005)

VCRC Bike said:


> This might be what you are looking for:
> http://www.rotorbikeusa.com/products/bsa_bottom_bracket.html


Read the product description a little closer and you will find that adapter is designed specifically for use with the Rotor 3D+ BB30 crankset and will not work for normal BB30 cranksets such as the SRAM or Cannondale SL BB30 cranksets.


----------



## VCRC Bike (Jul 1, 2009)

ms6073 said:


> Read the product description a little closer and you will find that adapter is designed specifically for use with the Rotor 3D+ BB30 crankset and will not work for normal BB30 cranksets such as the SRAM or Cannondale SL BB30 cranksets.


Doh! Good catch!


----------



## farva (Jun 24, 2005)

Zipp Vumaquad has a 30mm axle & fits in a standard 68mm threaded frame. Perhaps you can use their bearing cups with your BB30 Force cranks? No idea if the zipp cup stack height would work though. May require some tweaking/spacers. Personally I'd just get a new frame that uses BB30. They are pretty common now, even on lower end models.


----------



## Kontact (Apr 1, 2011)

farva said:


> Zipp Vumaquad has a 30mm axle & fits in a standard 68mm threaded frame. Perhaps you can use their bearing cups with your BB30 Force cranks? No idea if the zipp cup stack height would work though. May require some tweaking/spacers. Personally I'd just get a new frame that uses BB30. They are pretty common now, even on lower end models.


The Vumaquad is garbage, and SRAM discontinued it almost the moment they bought Zipp.

But the point of the OPs question is whether he can use a Force BB30 crank in a non-BB30 crank. The answer is an unequivacal NO. 

The crank isn't wide enough to get external bearing between it and the English BB shell, and the spindle too thick to get bearings between it and the inside of the shell.


----------



## farva (Jun 24, 2005)

I was only suggesting he might be able to make something like this work:

http://www.cyclingnews.com/features...-specialized-rockhopper-sl-singlespeed/147061


----------



## Kontact (Apr 1, 2011)

farva said:


> I was only suggesting he might be able to make something like this work:
> 
> http://www.cyclingnews.com/features...-specialized-rockhopper-sl-singlespeed/147061


If you are suggesting that the Force BB30 crank can be used like Vuma, it can't. The Vuma was designed before BB30 and was intended for English BBs - that isn't an adapter but the normal external BB cups.

Please re-read my last post about BB30 crank dimensions. They cannot be made to work with English BBs.


----------



## farva (Jun 24, 2005)

I hear you but how are they making this work? Is this not a specialized BB30 crank with zipp BB in a standard 68mm shell bottom bracket?


----------



## Kontact (Apr 1, 2011)

farva said:


> I hear you but how are they making this work? Is this not a specialized BB30 crank with zipp BB in a standard 68mm shell bottom bracket?


The one in the picture has a Specialized sticker on it, but the article says it is a Zipp Vukaquad crank. Whether that is or isn't I couldn't say, but we are not looking at a combination of a BB30 crank and an English BB shell. The frame and crank are protypes, so who knows what's going on, but I can tell what isn't happening.

Zipp cranks are not BB30. They have a 30mm spindle, but are much wider than BB30, like FSA's BB386. Since English BBs are about 35mm in diameter, there is just enough room to get the threaded portion of the external BB cups between the 30mm spindle and the shell.


----------



## RC28 (May 9, 2002)

Kontact said:


> Some 30mm cranks can fit into an English threaded BB, like BB386, but normal BB30s are too narrow - not enough space between the cranks for the bearings and the BB shell.
> 
> The Rotor cranks can do it, but those cups will only work on the Rotors - not a SRAM BB30.


Would something like this fit the bill for SRAM??

http://www.excelsports.com/main.asp...ad+BB+Adaptor&vendorCode=SRAM&major=1&minor=6


----------



## Kontact (Apr 1, 2011)

RC28 said:


> Would something like this fit the bill for SRAM??
> 
> http://www.excelsports.com/main.asp...ad+BB+Adaptor&vendorCode=SRAM&major=1&minor=6


Ah, no. That is an adapter to put an English BB crank in a BB30 shell. The OP asked about putting a BB30 crank in an English shell.

You can put 10 gallons of manure in a 30 gallon sack, but you can't fit 30 gallons of manure in a 10 gallon sack. I don't know how better to explain this.


----------



## nathan84318 (Aug 7, 2007)

Yes it can be done, have seen it weightweenies.starbike.com It does however slightly mess up the q-factor.


----------



## Mackers (Dec 29, 2009)

That worked by combining a Hollowgram crankset with an altered MTB spindle.
Won't work for SRAM cranksets.


----------



## Kontact (Apr 1, 2011)

nathan84318 said:


> Yes it can be done, have seen it weightweenies.starbike.com It does however slightly mess up the q-factor.


Then please explain to us how a crank with 68mm between the arms can suddenly get long enough to fit both a 68mm BB shell and bearings. Post a link, whatever.


This thread has gone to full-on ridiculous. Why is this so difficult?


----------



## asad137 (Jul 29, 2009)

Kontact said:


> You can put 10 gallons of manure in a 30 gallon sack, but you can't fit 30 gallons of manure in a 10 gallon sack. I don't know how better to explain this.


Maybe some more concrete numbers will help.

A BB30 crank has a spindle diameter of 30mm, and a spindle length of a little over 68mm (to allow for using thin shims to set the bearing preload).

An English threaded bottom bracket has 1.37"x24TPI threads and a 68mm shell width.

Now, according to Wikipedia, the internal diameter of an English-threaded bottom bracket is approximately 33.6-33.9mm. Let's take 33.9mm, because that's the most generous case (and it still won't work).

So you have a 30mm OD spindle and a ~34mm ID shell. Now, suppose you could press bearings directly into the threaded shell (which you can't), what does that mean for your bearing dimensions? It means your bearing needs to have a 30mm ID and a 34mm OD. In other words, in 2mm of radial space, you need to have room for a bearing inner race, the ball bearing itself, and the bearing outer race. 2mm is 0.079". First of all, this bearing doesn't exist. Second, even if it _did_ exist, the load capacity of the bearing would be, basically, crap.

Ok, so we can't fit a bearing _in_ the shell. How about outboard bearings like most modern threaded bottom brackets? This is fine, you can put bearings on the outside of the BB shell -- but now your bottom bracket width is > 68mm -- probably close to 80mm or so. Which means that a standard BB30 crank spindle (which, as you'll recall, is just a little over 68mm) won't reach from one side to the other.

*tl;dr:* you can't put bearings for a 30mm spindle inside an English bottom bracket shell, and if you put the bearings on the outside the crank spindle is too short.

Asad


----------



## ocean-ro (Nov 23, 2009)

asad137 said:


> Maybe some more concrete numbers will help.
> 
> A BB30 crank has a spindle diameter of 30mm, and a spindle length of a little over 68mm (to allow for using thin shims to set the bearing preload).
> 
> ...


This !


----------



## RC28 (May 9, 2002)

Kontact said:


> Ah, no. That is an adapter to put an English BB crank in a BB30 shell. The OP asked about putting a BB30 crank in an English shell.
> 
> You can put 10 gallons of manure in a 30 gallon sack, but you can't fit 30 gallons of manure in a 10 gallon sack. I don't know how better to explain this.


Oops! I stand corrected.


----------



## AndrwSwitch (May 28, 2009)

farva said:


> I hear you but how are they making this work? Is this not a specialized BB30 crank with zipp BB in a standard 68mm shell bottom bracket?


That frame's out of prototype. It can be yours, including a seat post, saddle and headset, for $470. Actually a pretty good price, IMO.


----------



## egebhardt (Feb 17, 2007)

asad137 said:


> Maybe some more concrete numbers will help.
> 
> A BB30 crank has a spindle diameter of 30mm, and a spindle length of a little over 68mm (to allow for using thin shims to set the bearing preload).
> 
> ...


Thanks for the numbers.
Wrong and Right.
The ZIPP Vuma Quad Bottom Bracket works, however, the 68mm-ish spindle length on a SRAM PF30 crank does not reach far enough so it does NOT work.

Too bad. I wanted to start standardizing all my bikes with BB30 or PF30 cranks. Now I know I can't.


----------



## oleritter (Mar 10, 2017)

Thread Resurrection -- 

With some Sram BB30 cranks, this is possible. Some are a true BB30, and the spindle is too short and it is not possible. But others have a longer spindle length, with extra space taken up with a spacer on the drive side and an adjusting/preload collar on the non drive. When both of those are removed, it becomes essentially a 386 Evo, or just like a Rotor crank. Preload is instead accomplished with a wave washer and spacers as needed. And a BSA30 bottom bracket, which has the same bearings as a BB30.
View attachment 320371
View attachment 320372
Just wanted to pass this along if anyone comes to read this thread. It can be done, with the right crank.


----------



## scott967 (Apr 26, 2012)

I think mainly Force 22 or S902 have that longer spindle. Maybe also one of the Quarq cranksets. I see also for 2017 SRAM offers what it calls Red BB386.

scott s.
.


----------

