When I stripped the bike down I found that the bottom braket was stuck. I could hear some crud rattling arround inside the frame. When I finally got the bottom bracket off I found that the entire space was filled with, what looked like cement. In fact the plastic tube from the bottom bracket was held firmly in place by the stuff. When I finally got the tube out I was able to use a knife to flake off about a 2mm thick layer of crud. I think this must have accumulated because the drain hole at the bottom of the bottom bracket was blocked.
The thread inside the frame was totally corroded. The corrosion had even eaten into the bottom bracket cups. I have run the old cups in and out a few times to clean the thread as best as I can and I have used a bottle brush to get the bit in the middle.
Can this frame be rescued? I think there is enough thread left to hold in the bottom bracket cups but is there some treatment I could use on the alloy to stop the corrosion from getting any worse? Any chance this sort of thing is covered by the trek lifetime frame warranty?
Click for full image:
The galvanic corrosion is likely to continue, however, it appears rideable and there are certainly enough threads in good enough condition to continue using the frame. When you next install BB cups lather up with lots of grease or anti-sieze and ride on!
I suspect you can get another 3-6 years of service out of this one...depending on the climate you live in and the extent of riding you do. EM3
if there's a lifetime warranty you could try trek, but be prepared for the response that it's due to lack of maintenance
to halt further corrosion and protect the aluminium, spray the area with acf-50, this stuff...
http://proviationshop.co.uk/shop/articl ... rosol.html
...squirt it through the holes so that you get it on the hidden areas too
whether there's enough metal to hold the bb is something you probably have to find by experiment, if it's too bad you could try a cf frame repair specialist to see if they can fit a new insert
if it's usable you need to prevent further damage, put anti-seize on the bb threads before fitting, park tool asc-1 for instance, after wet rides invert the bike for a few seconds to see if water drains out, if roads have been salted maybe give it a rinse with clean water, reapply acf-50 every few months, you can squirt it in via the drain hole
fwiw on my frame the only place water gets in is the top of the seat post, if i'm going for a wet ride i try to remember to fasten a bit of plastic film over the top with a rubber band, not elegant but it works well (it's bb30, if the bb shell fills up it soon washes the grease out of the bearings)
I think the Trek warranty is definitely a no go as I am not the original owner.
I actually came across acf-50 whilst I was searching the net since my first post.
They also make another product; corrosion block grease. I have ordered both and will try these out.
I have had the bottle brush attached to my power drill this afternoon and have managed to clean up the threads a bit more!
I am going to continue with the build. The bottom bracket cups can now be strewed in by hand and they do up nice and securely. I will just be a bit paranoid, listening out for creaking/cracking noises the first time I pedal uphill.
I don't think re-threading would work as the aluminium that is left is so thin and in such a bad state. To fix this properly the aluminium tube would probably need to be removed and replaced. I have no idea if this is even possible as it is bonded in and is pretty integral to the frame.
Edit: Apparently it is possible:
Does anyone know of a place in the uk that has experience of doing this job?
maybe they can source the replacement bb sleeve, they may need to get the old one out first to determine the required od, something suitable is probably available, for instance...
http://www.cycle-frames.com/bicycle-fra ... -BRACKETS/
How many drivers does a buggy have?
So let's just say I'm drivin' this buggy...
and if you fix your attitude you can ride along with me.
I'm unclear on a few things:
- Is the corrosion occurring where the carbon shell and aluminium insert meet? (that is, on the exterior of the aluminum shell)
- Or, is occurring at the the interior of the aluminum shell? What role does moisture play?
- If I decide to continue to ride the frame, is corrosion prevention grease superior to standard bicycle grease? If so, will it halt or slow the problem?
Thanks in advance.
If you ride in the rain you grease the crap out of the bottom bracket shell.
Any grease will work. Don't want to use grease then use automotive oil.
Any oil or grease will work.
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