Trek Madone CF-BB sleeve - the fix is here

[bikes4two]

Re-bonding Carbon Fibre Bike Bottom Bracket Sleeve
The original problem was discussed in this thread here

The Problem In Brief
I bought a 2007 Trek Madone 5.5SL in November 2013 only to discover shortly after purchase that the bottom bracket sleeve had become disbonded.

Cause of the problem (speculative)?
• The original bottom bracket sleeve was made of a lightweight alloy and was bonded to the bottom section of the frame for only about 33% of its circumference.
• The bottom bracket used was a standard English threaded square taper cartridge.
• When a square taper bottom bracket is tightened, the cups at each end of the spindle exert a compressing force on the bottome bracket sleeve and it is thought that this tightening action (torque of 70nm) put shearing stresses on the bonded interface which ultimately led to the disbonding.

Re-Bonding A Replacement Sleeve
Finding a suitable bonding medium was originally discussed here and following various postings a West System© G/flex 650-K repair kit was obtained from a local marine chandler’s. The mixed resin had a working time of 45 minutes at 25degC, an intermediate cure time of 7-9 hours with full hardness in 24 hours (although I left the resin to harden for 36 hours as the ambient temperature of my bike shed was only 10-15degC.

How Did The Original Sleeve Work?
I asked myself this question to better understand how and what to fit as a replacement. Informed by many of the forum comments I concluded that:
a. Those pedalling forces transmitted into the sleeve were mainly supported around the frame bottom bracket entry holes
b. And the purpose of the bonding was to keep the sleeve in place during bottom bracket tightening and during pedalling (although some pedalling force would also be transmitted into the frame at this interface too).

Replacement Sleeve
Replacing the bottom bracket sleeve with another flimsy Trek version was discounted and so a mild steel sleeve from Ceeway link here was obtained.

Some additional light machining work to the new sleeve was required as follows:

The original Trek sleeve had an OD of 37.5mm whereas the replacement Ceeway sleeve’s OD was 38.1mm. It so happened that the drive side of the frame’s bottom bracket hole had become slightly ovalised/worn (due to the wear action from cycling with the original loose bottom bracket sleeve) and the new sleeve was an easy push fit on this side. However the non drive side of the frame was not worn and the sleeve had to be reduced down to 37.5mm. (My thanks to Davin of Middleburn Bicycle Components link here for this who is a member of my local CTC group). A 5mm ‘fill hole’ was also drilled in the centre of the sleeve in preparation for the bonding process.

Both Brucey and Davin independently suggested that additional bonding could be achieved by ‘plugging’ the seat tube, down tube and chainstay tubes and making use of this area to provide additional bonding surfaces/anchor points.
The Plugging
Although I did not use the entire ideas expressed, the frame tubes were blocked off with glass fibre matting having first plugged them with a small quantity of bubble-wrap (to provide supporting surfaces for the wetted fibre glass).

The Bonding
1. The original bonding area in the bottom part of the frame would be extended either side by using an epoxy putty. The putty had adhesive qualities in its own right but this was enhanced by wetting the receiving surfaces with epoxy resin. This operation increased the bonding area from the original 33% to something like 66%.
2. A Dremel© tool was used to clear away the old resin and to shape the epoxy putty to leave a bonding ‘gap’ of about 0.5mm between the sleeve and bonding interface, with the whole area thoroughly cleaned with acetone.
3. The mild steel sleeve internal surface was covered in masking tape to protect the threaded areas from leaking resin as was the frame in areas vulnerable to further leakage. The outside of the sleeve was ‘scored’ with a series of shallow hacksaw cuts to improve bonding, cleaned with 60 grit emery cloth and cleaned with acetone.
4. The epoxy resin was mixed with a filler (the approved West System 406 Colloidal Silica) to form a gap filling mix and the bonding area thoroughly wetted prior to inserting the new sleeve. Any possible resin escape points were plugged, the sleeve inserted and the resin allowed to set for 36 hours.
5. The bike frame was then hung upside down and fresh resin introduced through the fill hole until the void was full. The hole was then plugged and the frame returned to the upright position to allow the resin to find its own level around the sleeve.
6. After 36 hours the replacement chainset and bottom bracket (GXP this time) were installed, gears trimmed and a test ride scheduled for next week.

Finally
If you have any queries about the bonding process, please feel free to post or PM me your question. As time and miles go by I will update this post as to the success (or otherwise) of this bonding effort.

And of course, my sincere thanks to those who contributed such thought provoking and constructive ideas in the linked threads.

[Brucey]

good work!

Who knows, it might be stronger now than when it was new!

cheers

[[XAP]Bob]

And people say you can't fix CF;)

[Mick F]

Yes, excellent work.
I await with great interest the results of miles and time.

Well done, and have a wonderful Christmas!

[matt2871]

Hi There,

Great post!!

Did this work??

I've just sheered my bottom bracket sleeve from the frame of my Trek Madone trying to remove a very tight bearing….. I've got a replacement sleeve from ceeway, but have lost my bottle slightly…… if it worked for you ill go ahead, if not i might just call it a day…..

Thanks in advance,

Matt

[bikes4two]

Hi Matt2871,

> Yes, the fix to the BB as described is very much a good one. That's 14 months on although maybe only 1500 miles (too many other bikes to share my pedalling legs with )
> I'm a heavy guy (90Kg) and by way of testing, I find a hill to climb up, get out of the saddle and 'honk' like a devil and look for BB flex by looking down at the front changer to see if the chainwheel moves from side to side. On the Madone it doesn't as far as I can see (but when I do this on my steel framed bikes, you can see flex, but you would expect this)
> I am confident in the bike and would go as far to say that the 'fix' I made has left the bike in a stronger position than when it rolled out of the factory given the cr*p method used by Trek in this particular model.

Do PM me if you have any specific questions. I documented this fix and have it in PDF form somewhere if you'd like it?

PS - Matt - re your problem in shearing the original sleeve whilst removing the old BB - was this a square taper BB? They require more torque that other types - if you go for the fix, I would recommend going for something other that square taper - something with lower torque (I cover this point in my PDF I think!).