For those of you who commented and asked about my rear light mount.

Yeah, the epoxy didn't hold, it came off after some tugging and it looks like it's the Topeak T part that it's not sticking to. So, unless you have some good plastic glue, don't try this or you risk losing your lights.



So I decided to try something else: rivets. I don't have any bolts with heads flat enough so they would not prevent the lights from sliding in, there isn't really much room. So I used small rivets, they have small, flat heads that can be easily filed off.



It would probably be a good idea to put some washers under the other side of the rivets, but I didn't have any small enough.



The end result seems OK. It holds pretty well and after filing off the rivets' heads the lights slide in, but it's a tight fit.

Looks good, I bet the rivets will hold!

Two lights... hmm..
Do you really need to tell them twice?

I could be wrong, but the mounting surface for the epoxy looks much too smooth for it to hold. You have to rough it up a lot to give it a great amount of surface area to adhere to.

However, the rivet idea is much better in the long run!

Sometimes it would be nice to tell them a third time!

Yes, I did roughen it up but it didn't work. The smooth surface that you see is the layer of epoxy itself.

Yes, the rivets look like they will hold. The holes were slightly smaller in diameter than the rivets so I had to push them in, so it's unlikely that the rivets would come out under normal usage.

I actually have three rear lights The third is on the seatpost. For two reasons: redundancy and because I'm obsessed with lights and symmetry

I would be shocked if JB Weld wouldn't have worked there, too. If the rivets don't work, check it out!

The front fork on my beater MTB didn't have anything to mount fenders on; now they are held in place by JB Weld. I'll need a Dremel to get them off :-).

-Greg

Never heard of that. I will definitely check that out. Sounds like something worth having.

Great minds think alike, LOL

JB Weld is amazing. My friend got a free SVT Focus airbox that was broken. The guy had all the parts and sent it over. We used JB Weld to put it together (with zero prep work), installed it in his Focus, and the thing ran for years with no issues. JB Weld is to the epoxy world as duct tape is to a redneck.

It's more than that Haven't you heard: "What's long and gray and holds the Universe together?"

So, JB Weld makes all kinds of adhesives (well, duh... of course). Amazon sells several. Is there one in particular you'd recommend? Looks like the WELD is their flagship product (8265-S & 8265), but they also have the quick setting KWIK. Perhaps I should get both

https://jbweld.net/products/jbweld.php

This is the one I use (I think it's 8265-S). I am definitely a convert. I can't think of two things that I might need to join together that this stuff wouldn't hold.

I have 4. One on the bike (in steady mode), one on my bag, one on my Camelbak and one on my helmet...all in flash mode. The lights on my Camelbak and helmet move more and are even more eye catching.

...And I have 3 powerful forward lights. I like my 3rd dimension.

HDPE , I'd think, plastic is just wrong, it flexes epoxy cures rigid
so fusing short of melting together ..
plan B the mechanical connection is better.

OP just didnt take the effort to find the right ID backup washer,
so went ahead nonetheless.. pop-rivets can always be drilled out and replaced

I just run the Dynohub powered lights , now only need one set...

Nice job.

Also, Planet Bike makes a bracket for racks. You could use two of them bolted to a piece of aluminum or some such material. Then bolt the aluminum to the rack. I like this idea because you can make it as wide as you want.
https://ecom1.planetbike.com/3108.html

I'm in the process of designing a bracket or light for one of my racks. My Blackburn rack does not have a bracket for lights. Also, my rack bag hangs over the edge, so I want to make a bracket that will extend outwards a couple of inches to clear the bag.

Nice job.

Gluing plastic with epoxy has always been a challenge. There are so many different plastics. I suspect the plastic of the pbsf is either ABS or Polypropylene. Regardless, the rivet should hold. You might find some free play after numerous cycle from removing the light. If you do find yourself having to remove and pop in some new rivets, I suggest adding some glue along with the rivets. JB weld, abs glue or even some acetone to help fused them together before riveting should last a long time.

Any polyurethane adhesive like Gorilla glue should bond it. Scuff with sandpaper, clean, apply and clamp. Generally, the glued joint is stronger than the material being bonded once it's cured.

Yeah, this was my first instinct. If it's PE then...you basically can't glue it. PE has waaaay low surface energy so basically nothing will stick. It's a wax, not a plastic technically.

Rivets...those should work though. Looks factory!

Thanks for the comments. Yeah, I don't know much about plastics. The rivets look like the best solution though. I don't take the lights out often since I carry the bike inside with me at work. If it becomes loose then yeah, I'll add some glue and re-rivet it.

Such a little thing and yet so much engineering

Pop-rivets FTW!

My mudflaps are riveted to my VO stainless fenders.
I fixed my Topeak Aerowedge bag with rivets when the seatpost strap came detatched.
I had all sorts of riveted parts on my Jeep.
The front fender extender on my previous plastic fenders was riveted in place.
I used rivets to secure the RiverCity "reacharound" mounting brackets on the fenders of one bike.
Rivets hold the bottom strap on my Berthoud bag, to secure it to the rack rails.

Its a little late to say it, now that you are done; but, when using poprivits on plastic, you should put a metal washer behind them so they don't expand the plastic and pull out of it.

I was thinking the same thing, but then, there might not be enough space for the washer when the light is clipped in.

So slight derail here. I too like the PBSF rear lights, but the 2 watt usb rechargeable cygolite blows them away. BRIGHT like shield your eyes at 100 ft. Plus they make a great seat post and rear rack mount.

Oh, I know. I did say that I'd like to put washers there but I just didn't have any that were small enough. I don't think it'll be much of a problem here though since the lights stay on the bike most of the time. I'll check them periodically and re-do if necessary.

Yeah, I like rivets too, very clean and strong solution to many problems.

I used a bit of Goop between my PB rack mount and the rack (I was only able to use one bolt to attach and wanted to keep it level). Later I decided to go with 2 lights and had to pry the mount off the rack. The Goop stuck even better to the plastic than it did to the powercoating on the rack and I think the mount would have stayed in place permanently without the bolt.