Major Rear Derailleur Failure w/ New Chain
#1
Junior Member
Thread Starter
Major Rear Derailleur Failure w/ New Chain
Even though I've been riding for over 10 years, I've never been very mechanically inclined, and so there are some pretty basic, stupid maintenance things that I sometimes leave to the local bike shop rather than deal with myself. But after what happened this weekend, I think I'm going to have to take care of these sorts of things myself from now on:
I brought my two-year-old Bianchi Vigorelli in to a LBS yesterday to have the (worn) chain replaced. The next morning, about 3-4 blocks into my ride, I heard a loud crunch, my drivetrain locked up, and I looked down and saw that my rear derailleur had flipped up into the spokes, bending the derailleur hanger in the process, and munching the chain.
Seems to me that the chain was the likely culprit, and I'm wondering if either the mechanic didn't install the chain properly (like it was too short, or maybe he didn't insert the pin correctly), or if the chain was somehow defective. I've never had a single issue with the bike before this.
I took it back to the bike shop today. The mechanic who did the chain wasn't there, but I left the bike with them and they said they'd assess the damage and get back to me in a few days. I'm still not sure how much (if any) responsibility they're going to take for this.
I'm attaching a few pics of the damage. Just wondering if anyone else thinks the chain is the culprit or if this is just a crazy coincidence?
I brought my two-year-old Bianchi Vigorelli in to a LBS yesterday to have the (worn) chain replaced. The next morning, about 3-4 blocks into my ride, I heard a loud crunch, my drivetrain locked up, and I looked down and saw that my rear derailleur had flipped up into the spokes, bending the derailleur hanger in the process, and munching the chain.
Seems to me that the chain was the likely culprit, and I'm wondering if either the mechanic didn't install the chain properly (like it was too short, or maybe he didn't insert the pin correctly), or if the chain was somehow defective. I've never had a single issue with the bike before this.
I took it back to the bike shop today. The mechanic who did the chain wasn't there, but I left the bike with them and they said they'd assess the damage and get back to me in a few days. I'm still not sure how much (if any) responsibility they're going to take for this.
I'm attaching a few pics of the damage. Just wondering if anyone else thinks the chain is the culprit or if this is just a crazy coincidence?
#2
Occam's Rotor
Join Date: Jul 2013
Posts: 7,248
Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 2366 Post(s)
Liked 2,331 Times
in
1,164 Posts
Looks like the dork disc saved your wheel. Bummer about the frame. That is a pretty major derailleur hanger bend. It is hard to tell from the picture, but I am guessing you are right -- not a coincidence.
#3
Senior Member
Join Date: Jan 2009
Location: San Diego, CA
Posts: 3,651
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 835 Post(s)
Liked 1,055 Times
in
740 Posts
Hard to say for sure but yes it's a possibility the mechanic did something wrong such as incorrectly changed your derailleur limit screws as part of the installation, installed the master link wrong, etc., etc., or it could just be coincidence. That's why you'll be encouraged to do your own work by posters here. Nobody cares about doing it right more than you, the owner of the bike and you can spend the time necessary to double check everything and it will give you the knowledge to sometimes spot trouble before it becomes catastrophic. Just sayin'.
#4
Junior Member
Thread Starter
Yeah, I'm glad I left the dork disk on there because you're probably right about it saving the wheel. As for the frame, I know that bent steel can be straightened, but I just wonder if this particular bend can be straightened without compromising the strength of the steel. It's a pretty serious bend, after all.
#6
Senior Member
If the chain had a pin (as opposed to masterlink) they may not have inserted it fully. or they re-opened it. It is just a bad design and why i only use masterlink chains (since it cost me a RD and hanger...).
I don't expect them to take the blame and buy you a new frame. You should have kept the bike as evidence and investigated yourself (with pictures here etc.) You basically charged the defendant with investigating and also made them the judge. Don't expect them to plead guilty.....
I don't expect them to take the blame and buy you a new frame. You should have kept the bike as evidence and investigated yourself (with pictures here etc.) You basically charged the defendant with investigating and also made them the judge. Don't expect them to plead guilty.....
#7
Junior Member
Thread Starter
#8
Senior Member
Join Date: Feb 2014
Location: Pasadena, CA
Posts: 4,847
Bikes: Schwinn Varsity
Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 1931 Post(s)
Liked 741 Times
in
421 Posts
Well that's strange. Was the chain routed correctly through the DR cage.... with regards to the little tab between the 2 jockey wheels...? I don't know what you call that tab.
#9
Junior Member
Thread Starter
If the chain had a pin (as opposed to masterlink) they may not have inserted it fully. or they re-opened it. It is just a bad design and why i only use masterlink chains (since it cost me a RD and hanger...).
I don't expect them to take the blame and buy you a new frame. You should have kept the bike as evidence and investigated yourself (with pictures here etc.) You basically charged the defendant with investigating and also made them the judge. Don't expect them to plead guilty.....
I don't expect them to take the blame and buy you a new frame. You should have kept the bike as evidence and investigated yourself (with pictures here etc.) You basically charged the defendant with investigating and also made them the judge. Don't expect them to plead guilty.....
But you mention the prospect of having to buy a new frame - does it look like my frame is toast? Or is that something that can straightened? I know that bent steel can be straightened; I just don't know if this particular bend is too severe for it to be reliably straightened.
This shop I took it to has been around for decades and has a pretty solid reputation, and in all my dealings with them in the past, I'd say 98% of the staff has been friendly and honest. It wasn't like I took it to some shady fly-by-night place that I'd never been to before. I guess we'll see how it goes. I investigated as much as I could with my limited mechanical knowledge, and sent photos to a cycling buddy of mine who used to work as a mechanic, and he was convinced the chain was at fault and strongly urged me to take it back to them and insist that they deal with it.
Last edited by Pavol Stromcek; 05-20-18 at 08:36 PM. Reason: clarity
#10
Junior Member
Thread Starter
For the first few blocks that I rode, the pedaling felt normal, at least, so I don't believe the chain was routed incorrectly. I was hearing a mild sort of popping sound from the drivetrain, however, and the chain froze up for a second shortly before I shifted to a larger rear cog and the failure occurred.
#12
Junior Member
Thread Starter
The cassette didn't appear worn, and this was the mechanic's opinion as well. He said the cassette didn't need replacing, so in a way, it might kind of be on him.
#13
Occam's Rotor
Join Date: Jul 2013
Posts: 7,248
Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 2366 Post(s)
Liked 2,331 Times
in
1,164 Posts
The link coming apart seems like the most plausible explanation.
As for the derailleur hanger, that'll buff right out.
(Nothing to lose bending it back. If the shop won't do it, get an Abbey HAG.)
As for the derailleur hanger, that'll buff right out.
(Nothing to lose bending it back. If the shop won't do it, get an Abbey HAG.)
#14
Senior Member
Join Date: Apr 2012
Location: Nor Cal
Posts: 6,016
Mentioned: 17 Post(s)
Tagged: 0 Thread(s)
Quoted: 1814 Post(s)
Likes: 0
Liked 923 Times
in
569 Posts
and can include loose chain jamming between the lower jockey wheel and the RD cage.
Anyway, the point was that there are possibilities that don't involve error on the mechanic's part.
#15
Mechanic/Tourist
If you weren't shifting to the large cog it can't be chain length (and it's quite easy to check for proper length) or limit screws, and a bad chain pin or master link is not only unlikely but quite easy to spot on the chain. You state you had just shifted, which sounds like the chain had seated on the cog properly. I don't see any way to apply blame to the shop, especially if your shifter is not in the large cog position. It's possible something flipped up from the road/path into the drivetrain.
#16
Junior Member
Thread Starter
I went back through the photos I took and found this one, in which you can kind of see the busted chain link: if you look just above the cassette, where the chain leaves the pulley, you can see it. Not sure if this really proves anything, ultimately, but the more I think about it, the more it seems that either the mechanic didn't insert the pin properly, or the chain was defective, because I don't think the chain could have broken like that from the impact of it being slammed into the cassette when the derailleur went.
#17
Junior Member
Thread Starter
(And if something would have flipped up from the road into the drivetrain, I think it would have to have been a very hard object, like a pebble, to cause that kind of damage, and I would likely have heard the resultant pinging or ticking sound.)
#18
Senior Member
Hard to tell for sure--was the broken link the one with the joining pin in it? That would be telling. The probability of the chain breaking in a short period of time under what sounds like modest load elsewhere is low. If the link came apart it could jam in the derailleur and the force could pull on it. Mistakes happen but the shop has control of how they handle this. Give them the chance to make this right--they have an opportunity to prove to you how they stand by their work and their standards for service.
Mechanically, I would carefully bring the hanger closer to sanely straight with knipex wrench pliars so as to not too much force on the hanger threads before aligning it with a hanger alignment tool. It'll probably be mechanically OK, although the paint on the hanger will likely be a bit messed up, and there's a small chance that it will break. If it comes back straight it'l be fine for use, though the odds of it braking if it gets bent again are much higher than before. Obviously new derailleur and chain.
Mechanically, I would carefully bring the hanger closer to sanely straight with knipex wrench pliars so as to not too much force on the hanger threads before aligning it with a hanger alignment tool. It'll probably be mechanically OK, although the paint on the hanger will likely be a bit messed up, and there's a small chance that it will break. If it comes back straight it'l be fine for use, though the odds of it braking if it gets bent again are much higher than before. Obviously new derailleur and chain.
#19
Senior Member
Join Date: Nov 2014
Location: Eugene, Oregon, USA
Posts: 27,600
Mentioned: 217 Post(s)
Tagged: 0 Thread(s)
Quoted: 18320 Post(s)
Liked 4,489 Times
in
3,338 Posts
I'm having troubles imagining how the chain could or would have popped out of the proper chain routing.
Inspection of the derailleur should indicate whether there is wear on the top side of the tab.
One can ride the bike just fine with the incorrectly routed chain, but it will cause the chain to sound a bit noisier than normal.
I can't say that would have definitely caused the bike to eat the derailleur, but if the chain was, in fact, routed incorrectly, then a large part of the blame would have to fall back on the shop.
#20
Senior Member
I went back through the photos I took and found this one, in which you can kind of see the busted chain link: if you look just above the cassette, where the chain leaves the pulley, you can see it. Not sure if this really proves anything, ultimately, but the more I think about it, the more it seems that either the mechanic didn't insert the pin properly, or the chain was defective, because I don't think the chain could have broken like that from the impact of it being slammed into the cassette when the derailleur went.
#21
Dirty Heathen
Join Date: Oct 2015
Location: MC-778, 6250 fsw
Posts: 2,188
Bikes: 1997 Cannondale, 1976 Bridgestone, 1998 SoftRide, 1989 Klein, 1989 Black Lightning #0033
Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 889 Post(s)
Liked 906 Times
in
534 Posts
I'm not a pro mechanic anymore, but I do turn wrenches on other peoples's bikes from time to time. I always try to give it a test ride on it's own wheels, not just on the stand, to make sure everything is OK before I give it back. Most of the shops I've been in do this too. Time or weather may have prevented it in this case though.
Bring the pictures back when you go to talk to them, esp, the ones that show the busted link, and that first one, where it looks like the chain is over the tab.
That way, they know that you know the condition / routing of the chain when it happened. Important, since the bike is back at the shop now.
Be cool, and give them the chance to own up to it first and make it right.
Bring the pictures back when you go to talk to them, esp, the ones that show the busted link, and that first one, where it looks like the chain is over the tab.
That way, they know that you know the condition / routing of the chain when it happened. Important, since the bike is back at the shop now.
Be cool, and give them the chance to own up to it first and make it right.
#22
Mad bike riding scientist
Join Date: Nov 2004
Location: Denver, CO
Posts: 27,274
Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones
Mentioned: 150 Post(s)
Tagged: 1 Thread(s)
Quoted: 6147 Post(s)
Liked 4,093 Times
in
2,325 Posts
I agree, doesn't look that worn. IME, chainsuck can be quite mysterious and unpredictable
and can include loose chain jamming between the lower jockey wheel and the RD cage.
Anyway, the point was that there are possibilities that don't involve error on the mechanic's part.
and can include loose chain jamming between the lower jockey wheel and the RD cage.
Anyway, the point was that there are possibilities that don't involve error on the mechanic's part.
I would also disagree that the chain can jam between the lower jockey wheel and the rear derailer cage. There's just not enough room for the chain to jump off the pulley and jam. It would rerail rather than jam.
I do agree that lots of stuff can happen that might not be the mechanics fault.
I went back through the photos I took and found this one, in which you can kind of see the busted chain link: if you look just above the cassette, where the chain leaves the pulley, you can see it. Not sure if this really proves anything, ultimately, but the more I think about it, the more it seems that either the mechanic didn't insert the pin properly, or the chain was defective, because I don't think the chain could have broken like that from the impact of it being slammed into the cassette when the derailleur went.
I can't absolve the mechanic entirely but there are other possible causes that have nothing to do with the mechanic. You said you were in the smallest chainring and went to make a shift. The smallest chainring is the one most likely to have chainsuck problems. The chain is under less tension from the rear derailer spring because the chain is effectively "longer" and more slack in the inner ring. The derailer arm is also flatter so it puts less tension on the chain. If the chain catches on the ring and starts to "suck" upward and suddenly releases, the energy goes into the rear derailer which swings that flatter arm upward and allows it to contact the cassette or catch the chain. That pulls the spring on the hanger upwards and the next thing you know the system jams and goes for a wrong way trip around the cassette.
The chain pulling apart is just a result of the having the connecting pin in the wrong place at the wrong time. That wrong way trip around the cassette puts a lot of stress on the chain and can even twist it. It looks like your chain is twisted just above the cassette. That twisting would separate the plate.
Bottom line, I wouldn't be quick to say that it was the mechanics fault. Have you been hearing mysterious chain slapping noise occasionally? It's hard to put into words but, occasionally, the chain will make a slapping noise or you can feel the chain move when you haven't made a shift or it may make the noise after you've shifted. That could be caused by a burr on the rings. Are the rings old? Do you see any signs of the rings having damage...it would show up as a shiny scrape on the ring? All these could have caused the problem. It could still be the chain but it could be other causes as well.
Finally, I hate to be the bearer of bad news but your frame is probably gone. Look at your second picture. The hanger is bent way back behind the axle and the slot for the axle is significantly wider than it should be. You might be able to straighten the hanger but it is more likely to just break off than bend back. And getting the dropout slot back to the width it needs to be would be next to impossible.
__________________
Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
#23
Senior Member
Join Date: Jan 2009
Location: San Diego, CA
Posts: 3,651
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 835 Post(s)
Liked 1,055 Times
in
740 Posts
I don't know, I think that's extremely unlikely. The chain was making a strange popping sound from the time I began riding, so I honestly think something was amiss from the get go. I thought it might have been a stiff link or something, so I kept riding another block or so to see if I could figure it out or if it would go away. Then the chain froze for a second, I eased up on the pedals, the chain moved again, I pedaled a bit more, then I shifted gears, and a few pedals later - bam.
#24
Junior Member
Thread Starter
Have you been hearing mysterious chain slapping noise occasionally? It's hard to put into words but, occasionally, the chain will make a slapping noise or you can feel the chain move when you haven't made a shift or it may make the noise after you've shifted. That could be caused by a burr on the rings. Are the rings old? Do you see any signs of the rings having damage...it would show up as a shiny scrape on the ring? All these could have caused the problem. It could still be the chain but it could be other causes as well.
The thing is, years ago, on a completely different and much older bike, I had different shop install a new chain, and the very first thing they said was that the cassette will have to be replaced as well (a few cogs were visibly worn), and possibly the chainrings. (In the end, the cassette was replaced, and the chainrings were deemed fine.) This particular mechanic was adamant - and rightly so - that thoroughly checking both cassette and chainrings was mandatory when even considering a new chain. That being said, should the onus be on every mechanic who is asked to replace a chain to thoroughly inspect both the cassette and chainrings?
Finally, I hate to be the bearer of bad news but your frame is probably gone. Look at your second picture. The hanger is bent way back behind the axle and the slot for the axle is significantly wider than it should be. You might be able to straighten the hanger but it is more likely to just break off than bend back. And getting the dropout slot back to the width it needs to be would be next to impossible.
#25
Junior Member
Thread Starter
But for argument's sake, I think when you have a sound like that, that's not glaring or alarming, you can't necessarily put the blame on the customer if it is discovered that the mechanic is at fault. I mean, speaking generally, I don't think a shop can expect every rider to have instant knowledge of what a particular sound could indicate and what they need to do in that moment.
It does sound as though there is a good chance that the chain was coming apart at that point and shifting put enough sideways stress on it to make the link come apart but still, not absolute proof, could have been something else. Was it just popping or was it skipping as well?
Changing your own chain is something most can learn and takes much less time than driving to a shop to drop off and pick up your bike not to mention however many days you have to leave it there. You basically just need to get a chain tool, remove excess links from new chain, install chain with a quick link (available separately if not included with your chain) and you're done.
Last edited by Pavol Stromcek; 05-21-18 at 09:54 AM.