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square taper BB to BB30, exist?

Old 07-21-14, 09:10 PM
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square taper BB to BB30, exist?

wanted to do a full shimano 105 10spd drop bar conversion kit to my Specialized Sirrus. Problem I'm running into was I could have swore the bike was BB30 BB but its a square taper BB. Are their any adapter or do I just need a different frame?
Thanks
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Old 07-21-14, 09:28 PM
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Several companies make adapter sleeves to convert a BB30 frame into a threaded bottom bracket.

You can measure the outer diameter of the BB shell of the frame to determine if it's BB30 or originally threaded.
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Old 07-21-14, 09:35 PM
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Hollow-tube BB axles are the latest thing .. lighter and stiffer .. for those you screw in external bearing races .
You can do that

BB 30 requires a whole new frame ... the above post was thinking you had one , then wanted to use square taper BB's..

Last edited by fietsbob; 07-21-14 at 09:39 PM.
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Old 07-21-14, 09:37 PM
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Unless I'm misunderstanding the question, the frame has a threaded bottom bracket shell and you are wanting to install a full 10 sp 105 group, which will use outboard bb bearings and will thread into your frame, no problem. If you want to run Shimano cranks, the fact that it's not a BB30 frame is good, because Shimano doesn't make any cranks with 30mm spindles anyway. FWIW, to run Shimano Hollowtech II cranks in a BB30 frame, you have to use one of several adapter options to make the BB30 bearings (which are designed for 30mm spindles) work with Shimano's 24mm spindles.
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Old 07-21-14, 09:47 PM
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My current BB is threaded for the square taper, I was hoping I could get a BB30 adapter some how but sounds like I just need a different frame.
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Old 07-21-14, 09:53 PM
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Originally Posted by Triaxtremec
My current BB is threaded for the square taper, I was hoping I could get a BB30 adapter some how but sounds like I just need a different frame.
10s 105 DOES NOT use BB30 it uses a threaded BB shell which you currently have. Amazon.com : Shimano 105 SM-BB5700 Bottom Bracket : Bottom Bike Brackets And Accessories : Sports & Outdoors

Last edited by dedhed; 07-21-14 at 10:03 PM.
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Old 07-21-14, 09:56 PM
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Originally Posted by Triaxtremec
My current BB is threaded for the square taper, I was hoping I could get a BB30 adapter some how but sounds like I just need a different frame.
Your current frame has a 68mm English threaded bb. It is not limited to a square taper bottom bracket. You say you want to put a full Shimano 105 group on the bike, I assume that includes 105 cranks. If so, it is no problem, the Shimano Hollowtech II outboard bearings will work fine, and are what you need for a modern Shimano 105 crankset.
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Old 07-22-14, 07:08 AM
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There are adapters that will allow select BB30 cranks for English threaded (BSA) frames.

Rotor has UBB (Universal BB)


Bdop has T30


Rotor cranks (e.g. 3D30, 3D+), SRAM BB30 MTB cranks, and Cannondale SL cranks with MTB axles can be used.

Note: It is important to have the longer axle. Both BB30 and BSA shell width is 68 mm (road frames). But BB30 frames have bearings inside the shell, thus BB30 road cranks have shorter axles than modern road cranks (24 mm axles) for BSA which use external bearing cups.

You can contact BDop (Bob Dopolina), who is a member of this forum, for further questions you may have.

Last edited by e_guevara; 07-22-14 at 07:12 AM.
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Old 07-22-14, 08:12 AM
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Again, the Shimano HollowTech II cranks DO NOT use a BB30 interface. They have external bearings that thread into the same 68mm shell that your current square taper BB is now sitting in.
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Old 07-22-14, 08:41 AM
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Like Demon said... Where does BB30 even come into the equation? If you currently have a square taper bottom bracket, you almost certainly have a standard 68 mm British bottom bracket shell, which is what your new Shimano 105 stuff would be designed for. Remove the old bottom bracket and install the new one. No adapter needed.
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Old 07-22-14, 09:37 AM
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Originally Posted by SkyDog75
Where does BB30 even come into the equation?
Originally Posted by Triaxtremec
My current BB is threaded for the square taper, I was hoping I could get a BB30 adapter some how but sounds like I just need a different frame.
It looks like he wants to run a BB30 crank...
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Old 07-22-14, 10:00 AM
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No, he is confused. No need for that crappy BB30 stuff. 10S 105 will be Hollowtech II, so it is an easy R&R job from his existing square taper.
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Old 07-22-14, 10:02 AM
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Originally Posted by demoncyclist
No, he is confused.
+1.
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Old 07-22-14, 10:06 AM
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Thanks for all the replies. I went and looked at my parts. I was incorrect as the crank is not shimano it's an unbranded fsa bb30 crank. After doing some research it looks to be the gossamer. So I could just by a different crank with the out board bearings and be ok.
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Old 07-22-14, 10:25 AM
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One other thing I will add, that's worth thinking about IMO: your Sirrus is a hybrid frame, so aside from any brake/type/mount issues that might be present in converting to a road group, the fit of a hybrid frame is quite different than a road frame. The idea of plugging in a road group on hybrid or mountain frames sometimes works out, but more often than not the frame dimensions are too far from ideal to make it worthwhile. Example: a good fit for me on a road frame will have an effective top tube length of 54-54.5 cm. A good fit for me on an XC mountain bike, effective top tube length: 58.5-59 cm. So, not even close to the same....... Bottom line: hybrids and mountain frames have different dimensions than road frames, to fit the same person. Just keep this in mind.
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Old 07-22-14, 10:43 AM
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Originally Posted by Triaxtremec
... the crank is not shimano it's an unbranded fsa bb30 crank. After doing some research it looks to be the gossamer. <sic>
FSA (Full Speed Ahead) is the brand of your cranks. Are you sure they're BB30? FSA cranks can also come with MegaExo BBs. Look for a "BB30" symbol on the crank (including the left arm).

So I could just by a different crank with the out board bearings and be ok.
What do you mean? Does your current frame with the FSA Gossamer have outboard bearing cups on the BB? If so, then you have the MegaExo version. BB30 cranks don't have cups as the bearings are inside the frame.

Shimano's Hollowtech II similarly has outboard bearing cups, and is compatible with some MegaExo cranks, the Gossamer being one IIRC.
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Old 07-22-14, 10:44 AM
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A photo of your crank and BB would be nice to clarify the issue.
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Old 07-22-14, 11:45 AM
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Originally Posted by e_guevara
A photo of your crank and BB would be nice to clarify the issue.

Crank came off a caad 10. So I'm just going to forget about that crank and buy one that will fit. Was looking at an fsa with the mega expo bb.
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Old 07-22-14, 12:27 PM
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Originally Posted by Triaxtremec
Crank came off a caad 10. So I'm just going to forget about that crank and buy one that will fit. Was looking at an fsa with the mega expo bb.
...


I'm overly confused now.

It sounds like you're taking the groupset off a factory CAAD 10 5 and putting it on a specialized sirrus hybrid... whilst converting to drop bars.

Yes?
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Old 07-22-14, 03:59 PM
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BB30 road crank won't fit into an English bottom bracket. The bottom bracket itself needs to be BB30. Sell the FSA BB30 crank and get another, either Mega Exo or Hollowtech, or even another square taper.
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Old 07-22-14, 05:32 PM
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and that is exactly what I'm going to do! I believe this will work great.

FSA SL K Light Carbon Road Bike Crankset MegaExo BB 46 36T N 10 170mm New | eBay

Thanks again for everyones help on my somewhat confusing thread!
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Old 07-22-14, 06:00 PM
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bb30 to 1.37/1.375" x 24 tpi shell

Originally Posted by cycle_maven
BB30 road crank won't fit into an English bottom bracket. The bottom bracket itself needs to be BB30.
Zipp VumaQuad did.

Irrelevant now.
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Old 07-22-14, 07:59 PM
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Even if you get the crank right, you still have the problem of the brakes.

Since the Sirrus is a hybrid, it will come with either brake bosses or brake tabs on the frame and fork. Finding the right brakes that will match the 105 road levers will be a challenge. Good luck.
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Old 07-22-14, 10:15 PM
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Originally Posted by e_guevara
Even if you get the crank right, you still have the problem of the brakes.

Since the Sirrus is a hybrid, it will come with either brake bosses or brake tabs on the frame and fork. Finding the right brakes that will match the 105 road levers will be a challenge. Good luck.
What's wrong with the brakes? I've seen a few other conversion with 105 levers and stock brakes.
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Old 07-22-14, 11:19 PM
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Originally Posted by Triaxtremec
What's wrong with the brakes? I've seen a few other conversion with 105 levers and stock brakes.
Read about the technical (mechanical) differences of caliper brakes, disc brakes, V-brakes, and cantilever brakes. The latter two have long and short versions, while there are mechanical and hydraulic versions for discs.

It has to do with brake lever travel vs. amount of cable pull, and the mechanical advantage of the brake system as a whole. Getting it wrong will result in a spongy feel or a very stiff lever. Levers are matched to the brakes to provide the best performance.

You never indicated what model Sirrus you had. The discussion was focused on BB/crank, and not on the brakes.

Last edited by e_guevara; 07-23-14 at 03:33 AM.
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