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Old(er) bike, new(er) derailleur, hanger problems.

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Old(er) bike, new(er) derailleur, hanger problems.

Old 11-20-21, 12:49 PM
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Cyclo_Tron
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Old(er) bike, new(er) derailleur, hanger problems.

TL;DR: I'm trying to mount a newer derailleur on an older bike. What's the best way to get a hanger that will match the old bike frame to the new derailleur?

Howdy, all. I've got an issue with a 2017 Norco XF3 that maybe ya'll can help me with.

A little history: buy the bike used. It never shifts right. All tuning leads to is which gears are hesitant to shift down, without actually fixing the hesitance. Shop's guess is bent derailleur hanger but that's why it's cheap(er). They were either lying or idiotic but that's a rant for another day. Have the bike for a couple of years, fall in love, etc. etc.

Fast forward to about 4 months ago. Bike is hanging on the wall, decides to drop the people's elbow on my roommate's bike from off the turnbuckle. Wake up to find them both in a heap on the living room floor.

Roomie's Specialized is fine. My bike, on the other hand, suffers a taco'd rear wheel and a bent derailleur hanger (or cage). Shifts terribly. All the tuning and bending I do doesn't really fix the problem (yes, with a new wheel). It consistently shifts worse than it ever did. I start entertaining the idea of replacing the derailleur (because maybe it can still be bent back) and find out the one on it is a replacement. I'm not terribly up-to-date on part's manufacturers but I learn pretty quickly that's it's the worst, oldest MicroShift you can find that still actually works on my bike (depending on how loose you are with the definition of "works").

That would explain a lot and should be a lesson to anyone buying used.

I start looking for a factory replacement. I'm not going to try to bend my way out of a derailleur that has who-knows-what indexing paired with the wrong shifter. Anyways, the factory derailleur is a Shimano Acera RD-M3000 Shadow and finding one, at least for me, was almost impossible. A lot of places don't have any left and the one's that do quote insane shipping times (6+ months). I start learning about matching new derailleurs to old ones, in terms of performance. I settle on the Acera RD-T3000.

Long story short here; I eventually get it fit on, replace the shift cable and housing, and the bike shifts better than it ever has. Photo since I can't yet link to the video of the derailleur shifting:

You'll note that the hanger is blue and appears to be made of plastic. Both of those things are true. You see, when the RD-T3000 came in the mail, it had an interesting B-screw arrangement that the MicroShift (and, I have to assume, the M3000) didn't have. I end up firing up SolidWorks and making this:


It takes about 45 minutes to print at 100% infill on a 3D printer. This is actually the second hanger I made for this thing. The first hanger (which is in the first photo) I made before I got the new derailleur in the mail and is basically a direct copy of the factory hanger. You'll notice the c-shaped slot in the latest hanger; that's part of that weird b-screw scheme. The big, square shaped head is for preventing the b-screw from just digging into the plastic and not doing anything.

Here's a few photos illustrating what the new derailleur has the the older one didn't:


That little c-shaped ring projects away from the derailleur where the old hanger has no such ring (I think). The hanger certainly doesn't make an obvious allotment for it. It's here, along with pictures of the old-style hanger fitting flush against the MicroShift:


Here's my question: am I doing this right? Ignore, for a moment, that I'm trying to do this is different types of plastic. More on that later. My main concern is if there's an easier way to put an new derailleur on a old bike. Is there another derailleur missing this "c-ring" setup that would mount more easily to the factory hanger? Am I just mounting the one I have wrong?

As an aside, the b-screw works on the derailleur with the groove cut into it. The bike shifts great; however, this process was driven by the fact that I use my bike every day to commute to and from school and I needed it back on the road quick. I'm wondering if I missed something obvious on the way and made this waaaaaay harder than it needs to be.

About the plastic: the first hanger was printed in PLA at 100% infill (maximum density). It lasted about 2 months of twice-a-day riding that included jumping a lot of curbs before it died. Oh well but that's not surprising. The second was printed at 100% infill in PETG. It only lasted about two weeks before I had to dump the bike one day and it fell on the derailleur side. I'm assuming the derailleur more-or-less did its job but, instead of breaking away clean from the frame or bending, it just snapped in half. Not sure but I'm confident it would have lived longer than the hanger in PLA had I not fell.

The reason I'm asking the question now is because I'd rather just buy a metal one that works for this frame/derailleur setup. If no such hanger exists BUT my design is good (read, I'm not doing something silly with that c-shaped groove), I can get one printed in Shapeways in materials much, much stronger than PLA and PETG for about $10. I can have one printed in steel for $50 but I think that would actually work against the derailleur doing its job in the event of a fall. Aluminum, the factory material, is about $103 to print and ain't gonna' happen.

Absolute worst case scenario, I can buy a reel of PETG for about $30 and keep making new hangers (a spool would be good for about 32 hangers). So, there's an emergency solution that keeps me on the road but, obviously, I'd rather put a bow on this thing for good. Thanks for any help and/or expertise

Addendum: here's the back of the M3000. Different b- screw scheme, it would appear. Did I goof?

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Old 11-20-21, 10:08 PM
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The hanger in the following link, looks to be the one that would fit on your bike, the derailleur that you bought, would fit on it without having to modify it or the hanger.


https://wheelsmfg.com/derailleur-han...anger-393.html


The RD-T3000 is a different type of derailleur to the RD-M3000, that's why they look different where they attach to the hanger.


https://wheelsmfg.com/blog/standard-...r-hangers.html
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Old 11-20-21, 11:14 PM
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That hanger is indeed the correct stock hanger for the stock derailleur and the 2017 XF3. It doesn't fit the T3000. That b-screw c-shaped thing interferes with it mounting flush. That's why the one in SolidWorks has the groove cut into it.

When you say different derailleur, what do you mean (besides model number, model year)?

I'm starting to think the thread in the 3D printed version of the hanger might be "out-of-clock"; that is, where the hardware starts threading into the "rear derailleur hole" is in the wrong position (?)
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Old 11-21-21, 12:27 AM
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Originally Posted by Cyclo_Tron View Post
When you say different derailleur, what do you mean (besides model number, model year)?
One is a conventional/standard derailleur the other one is a direct mount derailleur.

The direct mount derailleur needs a b-link (bracket axle unit) to attach it to a standard derailleur hanger.
A conventional/standard derailleur bolts straight onto a standard derailleur hanger without any extra bits.

c-shaped thing interferes with it mounting flush
Forget about the old derailleur and how it was attached, just attach the new derailleur so the 'c-shaped thing' is flush against the proper derailleur hanger.


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Old 11-21-21, 10:37 AM
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Ah, I see. Well, that diagram is actually really useful. It should mean the design will work fine, as long as the derailleur material is hard enough.

Appreciate the insight!
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