Bottom Bracket (tiny gap between cups and frame)
01-16-21, 02:53 AM
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Bottom Bracket (tiny gap between cups and frame)
I tried to post images but was not allowed since this is my first post!
I have stripped my bike to its frame to clean and rebuild. When reinstalling the bottom bracket I noticed a small gap between the cups and the frame on the bottom (on the top the cups are touching the frame and if i tighten any more the cups will dig into the frame.
Should I be concerned?
The spindle turns fluidly without any play, but it was really tough to thread the adjustable cup (fixed cup was smooth), but both cups have a small millimeter gap.
I have stripped my bike to its frame to clean and rebuild. When reinstalling the bottom bracket I noticed a small gap between the cups and the frame on the bottom (on the top the cups are touching the frame and if i tighten any more the cups will dig into the frame.
Should I be concerned?
The spindle turns fluidly without any play, but it was really tough to thread the adjustable cup (fixed cup was smooth), but both cups have a small millimeter gap.
01-16-21, 04:22 AM
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01-16-21, 05:46 AM
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With conventional bottom brackets, especially on better quality ones,
the shell should be faced(milled in metal working terms).
This brings the surfaces to parallel, and aligns everything correctly.
The cups would seat properly and the alignment perfect.
rusty
the shell should be faced(milled in metal working terms).
This brings the surfaces to parallel, and aligns everything correctly.
The cups would seat properly and the alignment perfect.
rusty
01-16-21, 09:35 AM
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That's a huge gap. Almost looks like the BB is cross threaded.
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01-16-21, 11:35 AM
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Someone please correct me on this if I'm wrong, haven't been working on vintage for too terribly long.
Make sure your cups are on the correct sides. The adjustable cup should always be non drive side... If my brain is orienting the pictures correctly, it looks like the adjustable might be on drive side. I did the same thing/had the same gap on the first old basket case I tried to fixie convert.. fortunately it was a cheap bike when new and even more fortunately I didn't strip or cross any shell threads. If they do seem to be on the wrong sides, dont use too much force when twisting them in the correct sides. If you feel a deal of resistance and suspect any cross-threading, take that frame to your LBS and see if they can chase the threads (or give any other advice) before it gets any worse.
And if you didn't already, liberally lube those shell threads.
Make sure your cups are on the correct sides. The adjustable cup should always be non drive side... If my brain is orienting the pictures correctly, it looks like the adjustable might be on drive side. I did the same thing/had the same gap on the first old basket case I tried to fixie convert.. fortunately it was a cheap bike when new and even more fortunately I didn't strip or cross any shell threads. If they do seem to be on the wrong sides, dont use too much force when twisting them in the correct sides. If you feel a deal of resistance and suspect any cross-threading, take that frame to your LBS and see if they can chase the threads (or give any other advice) before it gets any worse.
And if you didn't already, liberally lube those shell threads.
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01-16-21, 12:20 PM
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The only way the cups could have been reversed is if the shell is Italian threaded (or even less likely French) or the cups were horribly cross threaded. If the threads are correct and the cups installed on the proper sides, that frame is badly in need of facing.
01-17-21, 12:06 AM
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an uneven gap suggests that you might need to have the BB shell faced at the LBS
01-17-21, 07:30 AM
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OP - How did the cup gap look before you initially removed them?
