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Different MegaExo 6000 BB?

Old 01-17-15, 08:08 PM
  #1  
ian0789
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Different MegaExo 6000 BB?

So I am swapping some cranks around on bikes. I had a set of 53/39 cranks on a bike I wanted to move to a different one as an upgrade to that bike and put on a compact crankset to the one I was taking off the standard crank. So I picked up a FSA Gossamer crankset off ebay that came with out a BB but I had an extra laying around in my parts bin. When I took off the standard crankset I noticed that the MegaExo BB had a lip around it to fit the crankset in snug. It doesnt use anything for spacers so its a straight easy install. The crankset I was putting in is also a Gossamer but it uses one blue crush washer on the drive side and a wave washer on the non drive. So I attempted to see how it fit with the BB installed and it seemed like the spindle was a tad to short. My guess was the lips around the bearings just wouldnt allow for the space. So I took my other 6000 BB out of the parts bin and it was smooth, I swapped out the BB and reinstalled the crankset. I used the crush washer and wave washer and cranked it down to 38nm as per spec (went on the lighter side). The wave washer wasnt fully compressed like it seemed to be the 1st time around using the other BB but when I looked at two other bikes with wave washer they seemed more roomy.

So are some 6000BB only to be used with some Gossamer cranks and not others? I thought that all MegaExo 6000 BB was compatible with all energy and gossamer cranks and even as per FSA they claim to be. But if one uses a wave washer vs just the 2 crush or no washers then you have to find a different 6000 MegaExo BB?

So the new compact is on the bike with the parts bin BB I had and there is no play in the BB arms but it does feel a bit tight. I think or at least am thinking it will loosen up when it breaks in as the BB was a new take off I had picked up along the way. The 53/39 standard is off the bike and so is the BB that came with it and will be going on my other carbon bike I will be using for racing. So I am not worried about that as I know that is a perfect match.

Just wondering if anyone has run into similar issues with MegaExo 6000 BB's.

https://i.ebayimg.com/00/s/NzUwWDc1MQ==/z/U8IAAOSw1vlUr5ZS/$_58.JPG

https://i.ebayimg.com/00/s/NjAwWDYwMA==/z/EnQAAOSwU9xUPq1N/$_12.JPG

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So while I was posting this I came across that one crankset I took off and bottom bracket can only be used together as it uses the pinch bolt system while the crankset I was installing only uses the cap to torque down the crankarms. So I wonder IF the BB I had in my parts bin and installed is in fact meant for that crankset or if there is a different BB that I need to hunt down.
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Old 01-18-15, 02:31 AM
  #2  
jimc101
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Tried to read the above a few times, but still not sure what the main question is.

In general terms, external BB's never run as smoothly as internal/cartridge BB's if move by hand, when pedalling, this isn't noticeable.

With FSA MegaExo BB's, if in doubt, just replace with a Shimano HT2, they are compatible, and Shimano should be easier to find. The compatibility issue that you seem to be having is with the crank, not the BB, have you checked the techdocs to ensure you are assembling in the correct order? FSA Technical Information - FSA
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Old 01-18-15, 05:23 AM
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Originally Posted by jimc101 View Post
Tried to read the above a few times, but still not sure what the main question is.

In general terms, external BB's never run as smoothly as internal/cartridge BB's if move by hand, when pedalling, this isn't noticeable.

With FSA MegaExo BB's, if in doubt, just replace with a Shimano HT2, they are compatible, and Shimano should be easier to find. The compatibility issue that you seem to be having is with the crank, not the BB, have you checked the techdocs to ensure you are assembling in the correct order? FSA Technical Information - FSA
Yeah it sounds a bit confusing even when I read it so maybe this will help.

Bike 1 has a Standard Gossamer crankset with pinch bolts and cap. Bike 2 has a Compact Omega crankset. I bought a new compact Gossamer crankset to go on Bike 1 so I could take that Standard crankset and put it on Bike 2. The crankset I bought didnt come with a bottom bracket but I had one in my parts bin so I wasnt worried about not having one since the price was right. The crankset I bought uses the FSA Self extracting bolt and wave washer. When I took the crankset off and when to swap the new one in I it didnt seem to mount up with the spline a hair not all the way showing. My guess was because the BB has a lip around the spline holes.

Even tho they take the same 6000 BB it seems like there is 2 different versions. You could see looking at the external cups that they are not the same even tho they both are for a 24mm spindle.
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Old 01-18-15, 11:36 AM
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so if i understand this, a big if, you have a bike with a Standard Gossamer crank, removed it, and bought a Compact Gossamer crank, and found that it didn't fit the BB as you expected it would or to your satisfaction. if so, i would look at the cranks and see what's different about them.
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