Reattaching a metal dropout face plate on a carbon frame

[grams]

I have a carbon road bike frame with vertical dropouts. It has thin metal plates embedded in the carbon on either side of the dropouts so that the axle clamps against metal rather than bare carbon.

While removing the hanger screws a couple of years ago I managed to lift up one corner of the inner plate on the drive side. It eventually separated completely.

This makes reinstalling the rear wheel a total pain in the arse as I have to lay the bike on its side, put the plate on the dropout, then carefully manipulate the wheel in without knocking it out of place, which usually takes several attempts.

I can't ride without it because one of the hanger screws intrudes into the lock nut area, so it's needed to space the wheel above that.

I've tried bonding it back on with various household adhesives (epoxy, superglue, etc) but none has held for even one ride because doing up the QR always cracks the glue. About the only thing I've tried that's helped is heatsink compound, which is sticky enough to make the plate stay in place for one attempt.

Anyone have any suggestions?

[Paul]

If you only need to keep it in place while fitting: blue tack?

[CarlF]

Double sided (carpet) tape?

[Jurek]

The above two will fail when wet.
However, silicone bathroom sealant.......
ETA - let it cure before compressing.
ETFA - On second thoughts, compress just a tiny bit, like finger tight, before allowing it to cure.

[Ian H]

My suggestion would be to clean the surfaces thoroughly, add a very thin film of epoxy/Araldite, then immediately clamp it up very tight, perhaps using the wheel/QR, and leave somewhere warm to cure.

[Paul]

New bike.

[Brucey]

heat sink compound is (IIRC) often made using silicone oil as a base. Having put this onto the parts, you will basically never, ever, get them properly clean again, if they are rough and/or porous. Not clean enough to make a really good adhesive bond, anyway. It is arguably one of the worst possible things you could have done if you ever wanted to repair it properly at a later date.

My suggestion is that you either

a) take the parts to a carbon repairer (this is the sort of repair they do all the time) or

b) degrease the parts as well as you can (eg using acetone) and then roughen the surfaces (by taking off the top surface using ~200grit paper, changing it for fresh stuff several times, so that you get rid of the contamination and don't just spread it around.  An alternative is that you very lightly grit-blast the surfaces that you intend to bond. It is a very good idea to do this anyway with the metal plate.

Without knowing more about the exact frame design one cannot be sure, but it is often possible to secure such plates by drilling and tapping, so that some small csk screws hold the plate in place even if the glue is a bit iffy.

cheers