Wednesday, June 21, 2017

How To: Going 1x - Removing a riveted FD

Another how to! It's been a while but now that things are slowing down again (I missed track state championship because of some work I can get back to tinkering with things. And this week we'll dive right in to something I have seen some people mention doing or thinking about doing, but that maybe you are a bit timid about tackling yourself.

First, let's get the disclaimer out of the way. If you screw your frame up, that's on you. No manufacturer recommends doing this, and neither do I. But if it's something you are considering doing, you might has well have a guide to reference. Also note this is done on a Speed Concept, so YMMV from manufacturer to manufacturer. My guess is that all of them riveted on are done basically the same way, but who knows.

Now that the disclaimer is out of the way, let's address the inevitable question of "why."
I'm not going to try to convince you. If you found this post through searching, you have already read more than I can put into words here. If you just stumbled on this and are rolling your eyes thinking "what a waste of time" then nothing I can say will change your mind. That's not my intent anyways. So, let's get on with it.

Alright, so you are planning to remove your front derailleur and go "permanently" 1x. The simplest way to do this (besides buying a 1x bike) is just to de-cable and/or remove your front derailleur. Now (unless you have a clamp on style, in which case you're done) it's a matter of what kind of derailleur hanger your bike is equipped with. A couple of my bikes just had bolt on hangers, which is obviously best for this kind of stuff, since two bolts and you're done. My old P3sl has the hanger welded to the frame, and so even though the P3 is on track duty it's still got it's hanger. Some day I may grind it off, but I hate to as that is VERY permanent. Most (at least TT / Tri) bikes now are something closer to "semi-permanently" mounted to the bike. That is, riveted. That's the case with most of the carbon cervelo's, and, more importantly to me, my Speed Concept.

So, what does "semi-permanently" mean? It means you're going to have to do some "surgery" to get it off, but that you could re-install it at a later date with minimal work if you changed your mind. For that you'd need a rivet gun (yes, like you'd get at Harbor Freight for ~$5) and the corresponding pop rivets, but it's not a job out of the reach of a home mechanic.

So, the thing is riveted (and also glued) to the frame. So what do we need to get it off? I used
- Electric handheld drill w/drill bits (a couple of sizes)
- heat gun (not necessary but makes life easier, a blow dryer might work)
- hammer
- punch (could improvise with hex keys or something similar)
- screwdriver/something to pry hanger off.

Now, before we get into it too deep, it's important to understand the design of the rivet holding it on and how to get it out. What you'll see is what looks like a button head bolt, except there is just a hole in it instead of a place for a tool to remove it.

This is a rivet. Everything below the dome is out of sight when installed. The outer straight piece is broken off when installing the rivet.

this handy diagram I borrowed off the net shows how the rivet is installed. #3 is how it looks in your frame.

Now that we have an idea of how they got the rivet in, let's get to work on getting it out.

We'll break this FD removal into steps.
1.) Drill off the cap heads
2.) Punch out the rivet
3.) Heat the hanger
4.) Pry the hanger off
5.) Get rid of the debris

Step 1: Drill off the cap head
This one is pretty simple, you can expedite this process by starting with a bigger bit from the get-go, but it's best for "first timers" to start slow. Grab your drill bits and find one a little larger than the hole in the rivet. Drill into the head a little bit (as you can see in the diagram, the cap is not deep, you don't need to go any farther than where the cap lines up with the frame.) The reason I suggest starting with only a slightly bigger bit than the hole for now is that if you drill too deep, you just drill into the rivet itself, whereas if you start with a very big bit you may start drilling out the frame if you go too deep. That said, you will have to move to a bigger bit, maybe a couple of times. Just take it slow, repeat until the cap head breaks loose. Now, either repeat this step for each rivet before moving on, or move on to step two and repeat each step for each rivet.

You may want to throw something over the ring/chain as you'll get shavings everywhere.

Step 2: Punch out the rivet
Ok, so the head is off. Now we need to get the inside of the rivet out of the way. With the head off the easiest way is to grab your punch / makeshift punch (I actually used a hex key because it was laying beside me while I was doing it and I'm lazy. Anything hard, straight, that you don't mind whacking with a hammer and that will fit is perfect.) stick it in the hole you have made by removing the head of the rivet, and tapping it with your trusty hammer. It shouldn't take too much force to knock it back into the frame (so you know, be careful hammering really hard or you could literally punch all the way through the frame! That would be bad.)  The easiest way to get the trash out of the frame is removing the seatpost, turning the bike over and shaking a few times. If you are really lucky and have a larger hole at the bottom of the frame they might come out there on their own.

Now, repeat this until you have all the rivets removed.

Step 3: Heat the Hanger
Now, you can try to remove the hanger before this step. Depending on what kind of adhesive they used besides the rivets, it may come off with only minor amounts of prying. On the Trek they used some epoxy, so it really needed heated to loosen it up a little bit. Like everything else, take your time, a heat gun gets REALLY hot really fast. You just want to warm the hanger and adhesive below it up up, not turn it white hot. When in doubt, go slow, you can always turn the heat gun back on.

heat it up, don't burn it up

Step 4: Pry the hanger off
Alright, so it's time to take remove the hanger. Your method of prying it off may differ. I used my screwdriver, stuck it through the opening in the hanger (where the derailleur mounts) and pried it off. It took minimal force. You could also probably do it with pliers or any other things. Use some caution and common sense... the hanger is probably metal, and you just warmed it... so grabbing it with your hand is a bad idea.

Step 5: Get rid of the debris
If you haven't gotten rid of the back half of the rivet (now in your frame) this is the time to do it. If you remove the seatpost make sure to mark where it was for reinstallation. It's possible that if you took off a little outer layer of paint/material when you pried off the hanger you'll need to sand it down to even to prevent further fraying. In the picture below you can see in my case the glue took a little bit with it when removed.  Not a big deal, but also not for the feint of heart. This is also the time when you should figure out how you're going to dress it up now. I went cheapo mode and just painted the area black... but you could get creative and make it look considerably nicer (something I may do down the road)

Removed! Semi Perma 1x

Is it worth doing? It depends. For me, I like to tinker on stuff, like smooth lines (no hanger sticking out) and obsess over any potential aero gains. Are there any? Most likely some, and some reports suggest that the hanger itself is the biggest portion of that drag. Whats a few watts mean to you? Again, hard to answer, a lot of us spend a lot of money for a watt or two... so doing something (relatively) cheap/free seems like a good bang for your buck. Again, not suggesting it's for everyone, but if you're going to tackle it, here's a way that worked well for me!

 Thanks so much for reading, I really appreciate it!

- Christopher Morelock

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