I have an old Trek 720. It has been repainted but the head badge was just stuck back on. I removed a layer of black goo from the back with the Dremel and was wondering what type of adhesive would be best for sticking it back on.

What type of paint/clear coat is on the bike? Do you want to be able to remove the badge in the future? Andy

.025" thick 3M VHB tape is what I use.

Basic silicone should work fine. I used it on my Trek 360 and Lotus and I know those badges are going nowhere.

I'll second the 3M VHB tape. I've been using it for years and never had a badge fall off.

I swear they used roofing mastic tape on those badges. I was there in the years where they used 2 screws to hold the badges on. Convenient way of telling if it is possible I built a frame.

3M brand Emblem Adhesive

It comes in a tube that is slightly larger than the tubes of Model Airplane Glue from 55 years ago..........don't mistake it for that though, because Emblem Adhesive is what glues the badges, nameplates, letters, etc on to automobiles/trucks/suvs.

There is nothing better in this world for that purpose.

Speaking of 55 years...that's probably the last time any OEM auto company used adhesive to attach badges, nameplates, letting etc. onto a car. Double sided tape is the norm, or some sort of mechanical fastener in certain circumstances.