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Old 09-15-08, 01:52 PM   #1
desertdork
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Running a Phil BB "backwards"??? What difference will it make?

I'm posting this in reference to my recent thread here:

http://www.bikeforums.net/showthread.php?t=465239

The dealer's mechanic reversed the mounting rings during the installation of my Phil bb to make it compatible with the defective (reversed British) threading on my frame. In the process, he pressed the left-hand-thread ("red coded") ring onto the non-drive side of the bb cartridge.

Can I expect any issue...performance/compatibility/longevity-wise...if I reinstall this bb on a non-defective replacement frame of the same make/model? Will the bottom bracket care that it's running backwards? With the ring pressed on there, I won't be able to maintain the normally prescribed cartridge orientation.

This is probably a dumb question, and I willingly confess my ignorance on this matter.
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Old 09-15-08, 02:37 PM   #2
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I've reversed BBs before for various reasons. As long as nothing's been damaged you should be able to reinstall it "correctly" in another frame.
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Old 09-15-08, 04:35 PM   #3
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There is no reason the BB would run backwards. The cups have been reversed because of the threading problem on your bike.The BB shell can still be put in correctly. It really should be if the spindle is offset towards the drive side. bk
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Old 09-15-08, 06:10 PM   #4
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Originally Posted by bkaapcke View Post
There is no reason the BB would run backwards. The cups have been reversed because of the threading problem on your bike.The BB shell can still be put in correctly. It really should be if the spindle is offset towards the drive side. bk
Agreed, but it really doesn't matter if its backwards. The ends of the spindle body are the same, the only reason one would need to correctly orient it would be if the spindle has an offset.
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Old 09-15-08, 06:35 PM   #5
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I have used a Phil BB with offset 'backwards' to improve chainline - so agree there is no problem doing it. The bearings do not have a 'forward/backward' rotation to them.
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Old 09-15-08, 08:28 PM   #6
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I'm surprised the crank fit without hitting the chain stay
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Old 09-15-08, 09:16 PM   #7
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Thanks for confirming that there is no rotational preference for the bearings.

But the last post made me take a closer look at the BB spindle. With a crude measurement with a steel mm rule, it appears the 'normal' drive side of the spindle is possibly a hair (~0.5mm) shorter than the 'normal' non-drive side. It's probably symmetrical by definition for all I know.

It looks like it should work, then. I would exchange it if critical but am hoping to avoid that additional hassle.

Edit: It appears the smallest offset on a JIS Phil BB is 4mm. So this must be symmetrical. Thanks for your help.

Last edited by desertdork; 09-15-08 at 09:32 PM.
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