Loose carbon bottom bracket shell
01-15-21, 09:13 AM
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Loose carbon bottom bracket shell
Hi there
I have a BMC Teammachine carbon frame that has an issue with the press fit (BB86) bottom bracket. The carbon shell on the non-drive side has come loose as shown by the arrows on the picture. Is it worth trying to fix it with some kind of epoxy or retaining compound or should I aim for a professional repair if that's even possible.
Anyone had similar issues? And results?
Kind regards
Kim
I have a BMC Teammachine carbon frame that has an issue with the press fit (BB86) bottom bracket. The carbon shell on the non-drive side has come loose as shown by the arrows on the picture. Is it worth trying to fix it with some kind of epoxy or retaining compound or should I aim for a professional repair if that's even possible.
Anyone had similar issues? And results?
Kind regards
Kim
01-15-21, 10:18 AM
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Not being familiar with this frame's construction I ask if the loose part is the bearing from the BB or is a machined insert/cup that the bearing fits within? I believe you are talking about an AL insert that was bonded into the frame's carbon shell.
If this is the case then here's my thoughts- If the insert can be easily (with no additional damage to the carbon surrounding it) be removed then a home repair might be doable. The reinstalled alignment will be somewhat important so if the insert is sloppy and can rock a bunch then some way to hold it square to the main triangle should be tried. I have used 3M's DP460 for carbon frame repairs (and was recommended it by a bike company's tech people for stay/dropout rebonding). Getting the mating surfaces clean and prepped for the bonding is rather important.
If the insert can't be easily pulled out then I suggest a professional job. These types of repairs can be very simple and long lasting if done right the first time. But they can mushroom bigger and cause all kinds of frustration if not done well. Andy
If this is the case then here's my thoughts- If the insert can be easily (with no additional damage to the carbon surrounding it) be removed then a home repair might be doable. The reinstalled alignment will be somewhat important so if the insert is sloppy and can rock a bunch then some way to hold it square to the main triangle should be tried. I have used 3M's DP460 for carbon frame repairs (and was recommended it by a bike company's tech people for stay/dropout rebonding). Getting the mating surfaces clean and prepped for the bonding is rather important.
If the insert can't be easily pulled out then I suggest a professional job. These types of repairs can be very simple and long lasting if done right the first time. But they can mushroom bigger and cause all kinds of frustration if not done well. Andy
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AndrewRStewart
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01-15-21, 10:21 AM
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how old is the frame? sounds like a manufacturing defect to me. I'd ask BMC first. even it's no longer within their warranty, they'll know the best option for their own product.
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01-16-21, 06:47 AM
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Its the insert which is bonded within the frame but I haven't tried to wiggle it out. I am kinda worried that it might strip the surrounding carbon but will look further into it.
The frame is from 2013. I did reach out to BMC who replied that it can be fixed with adhesive. Alternatively the insert can be replaced, yet for a quote I would have to bring the frame to the shop. I guess I will take it there and see what a refurb would cost. Any advice on how much the frame is worth investing into?
The frame is from 2013. I did reach out to BMC who replied that it can be fixed with adhesive. Alternatively the insert can be replaced, yet for a quote I would have to bring the frame to the shop. I guess I will take it there and see what a refurb would cost. Any advice on how much the frame is worth investing into?
09-09-21, 08:56 AM
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Shimano BC1.37x24 shell
Hej people
Recently the shell, not the frame boss itself,that the bb threads into has come loose, such that removing the drive side bearing causes it to spin. When the shell spins, obviously the separation of the bearing from the shell / barrel is impossible.
The operation began as a result of excessive noise coming from Non drive side 1st, then progressively in concert with Drive side; to replace a scrubbed bearing on Nds as well.
Question: is the barrel/shell 1 piece, and can I remove it to clean and re-cement to frame boss?
Help please, it has been 6 days without a fix/ride!
Recently the shell, not the frame boss itself,that the bb threads into has come loose, such that removing the drive side bearing causes it to spin. When the shell spins, obviously the separation of the bearing from the shell / barrel is impossible.
The operation began as a result of excessive noise coming from Non drive side 1st, then progressively in concert with Drive side; to replace a scrubbed bearing on Nds as well.
Question: is the barrel/shell 1 piece, and can I remove it to clean and re-cement to frame boss?
Help please, it has been 6 days without a fix/ride!
