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Bottom bracket confusion

Old 06-07-12, 10:31 AM
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gamedic
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Bottom bracket confusion

I just bought a frame off Ebay. The frame is a Rocky Mountain Solo 50ac. The frame is bare it doesn't come with anything on it. I want to build it up with pretty nice components. I decided to start with the bottom bracket. Bottom brackets seem very confusing to me. Can anyone tell me which one I need. I think it is a 68mm english thread. Will a gxp or bb30 work or am I totally off track? I have no idea what the different types are. Thanks.
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Old 06-07-12, 02:47 PM
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I did a little searching on the internet and found a few builds. A couple of builds used FSA Mega EXO bottom brackets, but when I research that bottom bracket it wasn't very well rated. A couple of builds used a Tiagra bottom bracket, which I think may be lower end. A third bike had an octalink bottom bracket. I can't tell from the pictures of the fram I bought, but I think it is externally threaded. I guess I will have more to go on when it arrives.
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Old 06-07-12, 03:47 PM
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I'm in the same project right now. Pulled the square taper BB and will be installing the ISIS type with splines so to fit the modern stuff. One thing you will need to do is figure out the measurement of the spindle length so your chainset will properly fit and align.
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Old 06-07-12, 03:54 PM
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Crankset design has influence on type and length of the BB.
If you want the current generation of cranksets
the bearings are external, they screw into the frame.
the BB spindle is a tube attached to the crank arm..

To best insure better fit , Buy all the parts at once,
not BB first then crankset.

Doing business wit your local Bike shop is advised,
as there are less tools you also have to buy
and trial and error returns shipping is avoided.
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Old 06-07-12, 04:38 PM
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To summarize what's already been said, because it's so simple:

You know your BB thread: 68 mm, English. It is not BB30, you need to buy a BB that is 68mm English. Commonly just called an English road bike BB. (as opposed to Italian).

Simply buy an English bottom bracket either WITH whatever crank you buy, or buy it separately, but only after you know which crank you're going to buy. The crank will tell you which English threaded BB you need. The most straight forward thing is just to buy the BB with the Crank, or if not, just buy one that is specifically compatable with it (i.e. made by the same company).

If you're really into "high quality" boutique BB's, again, all you need to know is which crank you'll be using, and get the correct English threaded BB from that boutique company.

Me, I just buy the BB with the crank, or just buy the BB from the same company. I'm just into basic BB's and don't care about ceramic, or other supposed quality factors since although cheap BBs may wear out quicker, they're very cheap and very easy to replace. (but interestingly, I have only 'worn out' one BB in my life).

Last edited by Camilo; 06-07-12 at 04:44 PM.
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Old 06-07-12, 04:43 PM
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You need an English threaded bottom bracket to match whatever crank you choose. No, a BB-30 will not work.
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