Question about epoxy and plastic
 

Silly question... does anyone know what kind of plastic the hard bottom shell of a saddle is made of, and can it be epoxied? I'd like to bond a piece of plastic to the bottom of a saddle (think Carradice hack or place to mount a light).

I've tried the search function, but can't find anything relevant.

I would think if you rough it up a little so there is more surface area to bond to, any heavy duty epoxy should work. I wouldnt count on anything holding to a smooth surface though.

This ^ Just use sandpaper on both surfaces, it should work fine, as long as you make sure they stay pressed together and cure completely.

Well, unless you used some sort of solvent cement on it, I bet it'll peel right back off. Seat base material is designed to flex, so any epoxy bond will start breaking right away.

I've had decent success with TAP Plastic's E-6000: http://www.tapplastics.com/shop/product.php?pid=129

There's also Shoe Goo, which is basically the same stuff, as is a brand called Goop. The nice thing is that it'll hold securely, but if you ever want to remove it, it'll come off without leaving a mark.

Most seats I've seen the bottom is made from a flexible engineering plastic. That stuff will resist nearly every type of adhesive out there, including superglues, and two part epoxies. Rubbery glues like E6000/Shoe Goo/Goop will hold that kind of plastic better than just about anything else.

Gorilla tape.

There are epoxies designed (and labeled) to work on plastic.

Epoxy will NOT stick to that kind of plastic.

Shop around for a different seat, or build a new seat from scratch.

Like this bike:

http://i134.photobucket.com/albums/q...IMG_0008-1.jpg

Here, I made a "banana seat" from scratch, using Epoxy over styrofoam, BUT notice I also replaced the seat-post with a fiberglass-over styrofoam board. So I was able to mount the seat without a sissy bar.

Thank you, guys! I'll try experimenting with TAP or a similar product, and if that doesn't work, I'll move on to plan B. :)

If it is ABS plastic, which it probably is, you can buy a can of ABS cement/solvent from the hardware store in the plubing section, and it can melt the pieces together. This works great on many things around the house.

It's not ABS- ABS is fairly rigid. Bicycle seat bases need to be flexible. I bet it's polyethylene-based, but that's a WAG. Dammit, Jim, I'm a bicycle mechanic, not a chemical engineer!

Carradice make a metal saddlebag adapter that clamps to the saddle rails.

I'll probably wind up using that or something similar- simpler than the rigamarole I had planned :D