Re-visiting stripped RD hanger
 

I am not a mechanic and even if I was I have never seen this issue before. The mechanic at the Co-op hadn't seen this either and thought the bike is done (or would make a fixie frame only).

I am helping a friend who bought a $20 Norco 10 speed with a Shimano Light Duty drive train. He had shifting issues and I couldn't align it properly. Either the rear would be aligned when using the large chain ring or it could be aligned to the small ring but never both. To my eye the RD seemed to have "bit" of play (it could sway slightly inwards and outwards).

I brought it to the co-op and was advised to try stripping out two chain links (chain was very loose) but that didn't save the day. I tried a second RD and found that it's hanging bolt was loose in the hanger. I stripped down both the old and the second RDs and discovered that the original (old) RD was missing an internal seal. With the seal gone the hanging bolt would reach just that much farther through the RD and thread into the hanger (only a tiny bit). Because it was so loose it had stripped the threads of the hanger.

Since he will need a new RD I'd like to do this reasonably inexpensively. I see online that I can get a 7mm dropout saver for about $20 but also see dropout saver kits for $70.

Do I need a full kit or can I just order a single saver?

Also do I simply use an 11/32 drill bit to widen the existing hole? Should I find a drill press instead of a hand drill? It seems too easy,which is also why I am asking before I go get a dropout saver.

Lastly could I just get a claw hanger mount and attach that to the frame in the hanger hole and then attach an RD to the claw or will that not work because claw hangers are usually mounted to piece that fits in the drop out?


https://cimg3.ibsrv.net/gimg/bikefor...0261d7dac0.jpg

Looks pretty marred, but you could try running a thread chaser through there in an attempt to repair the threads. The good news is that steel threads can be repaired, aluminum is usually softer and harder to fix without an insert/saver.

Heilcoil or equivalent.

The threads don't look too bad to me. A tap (M10x1.0) may clean it up.

...if it won't clean up with a tap to where it will hold a derailleur securely, this is your next step and best option.
I don't know what a "dropout saver kit" is, but a helicoil in this spot is a snap to install and will last forever or until someone breaks the hanger.

And they don't cost anywhere near $70.

https://cimg6.ibsrv.net/gimg/bikefor...ddcd81f234.jpg


https://www.amazon.com/Thread-repair...kit+m10x1.0%29

Of course use a drill press if available, to get the hole square. A single Saver should suffice, but this kit calls for a 15/32" bit so check with the one you get. Should work well and easier to install than a Helicoli, which I am partial to otherwise.

repair insert comes in from the back side then you hold it with a wrench , it has a hex..
while tightening the RD with that other wrench..

The "Dropout Saver Kit" has the clearance drill bit and a number of the internally threaded insert bushings so it's intended to repair multiple bikes. Hence the cost.

A single bushing is only a few dollars and the needed 15/32" drill bit is in any 1/2" drill bit set or available at any hardware store. As fietsbob noted, the bushing has a hex on the inside of the dropout that you hold to tighten the derailleur's mounting bolt.

Ok all. I will get a tap and try that 1st. If no luck will try the next options.

Thanks WGB

Davidad - tried the video but no luck loading.
Anyway - tried to chase the threads with a tap tonight but still slipping.

I'm handing it back to owner and suggesting he call around to see if anyone locally has used a helicoil or is willing to drill out the RD hanger hole to install a frame saver. I don't have a drill press and would be running a hand drill and I'd rather not learn how to drill straight and level on someone else's bike. Same goes for helicoil If I screw it up I'd feel obligated to replace the frame and that would not be stress free.

I'm sure either method will be very cheap but he can make the call.

WGB

I put a dropout saver into a hole reamed out with a hand-held drill. It would be nice to get it precisely square and so forth, but (a) clamping the bike to the drill press can be an interesting exercise, and (b) handheld works well enough.

As @fietsbob noted, you'll be holding the dropout saver with a hex wrench while you screw the derailer on. If you've used a properly sized drill bit, the fit is snug enough you'll get minimal wiggle from the mounted derailer. Note it might be worth checking the hanger alignment before you put the derailer on.

the ones I'm familiar with may be fitted using a tapered hand reamer ,
with the insert fitting in a tapered hole from the inside out,
they being tapered as well , so tightening the derailleur mounting bolt outside, pulls it tighter.

If you do not ream the hole out too large..