ghostamongyou

I'm a hair shy of 6' and a bit south of 215lbs. All of my gears were adjusted and indexed fine and working well without issues. So here's what happened:

I took a portion of a paved walking/biking trail in my area that I hadn't tried before, one with a portion that has a VERY steep incline. It couldn't be peddled while sitting; it was either stand up and power through it or get off the bike and walk. I chose the former. That's when what you see in the photos happened. I powered through four or five peddle revolutions and then the entire rear shifting mechanism just bent and collapsed in on itself, wedging into the wheel spokes. I had to do some serious yanking around on it just to bend it back out enough for my bike to be able to free roll while I half coasted, half did this weird skate board type shuffle back to my car.

What the...?
Has this happened to anyone else?
My bike mechanic that I took it to for repairs seems to think I should have heard some warning 'tinks' when it started hitting the spokes. I didn't hear anything. One moment I was standing and powering through a cadence in the lowest gear up a steep incline, and the next moment I was at full stop with my rear derailleur mangled into the wheel.

*seems the images won't go through because I don't have the mandatory 10 posts yet or whatever.

**ok, bumped 10 times, so let's see if the images will post now.

ghostamongyou

So can I just bump my own thread nine more times to get the 10 posts needed to post images...???

dabac

That does happen every now and then.
Depending on how the rear wheel is laced, high torque as in pedalling hard can pull the spokes closer to the derailer.
Standing and tilting the bike side-to-side can put some sideways load on the wheel, also pushing it towards the derailer.
Another thing that can contribute is poorly set limit screws, and/or forgetting what gear you're in.

I suppose flexy frame could contribute too, but isn't something I've encountered.

ghostamongyou

Anything I can do to avoid it happening again? or should I just walk the bike in really steep places and all together avoid putting that much torque on it?

CliffordK

Those discs are supposed to protect the spokes from eating the chain or derailleur. But, they aren't particularly popular, so it looks like they've shrunken over the years. They still should protect the spokes from chain drop, but not from snagging the derailleur.

As far as what happened. You have two adjustments on the derailleur.

• inline adjuster where the housing enters the derailleur. This adjusts the indexing.
• High/Low stops. This adjusts the maximum range the derailleur can travel. So, the indexing can be right, but the stops could be wrong.

Also, the low end Shimano derailleurs (Tourney, and similar derailleurs) have a lot of flex. That would make adjustment difficult. Go up about 3 grades, and the derailleurs should be much easier to adjust and last longer. Deore? I'm not quite what the mid-grade MTB derailleurs are today.

ghostamongyou

Would you say it's definitely a stop adjustment issues or is it possible that the stops could be adjusted correctly but the sheer force applied is enough to somehow bend the component inwards enough to get tangled in the spokes regardless? or is it unlikely to know for certain either way?

I was exerting some very significant force on the bike to power creep up that incline when all this happened. I remember hoping I didn't bend or break a peddle somehow, as I've never subjected the bike to those kinds of forces before and didn't really know what to expect. I was REALLY powering through that little stretch before everything buckled on me.

I'm just afraid of it happening again.

I'll keep in mind your suggestion about investing in higher quality components at some future point.

CliffordK

Many people can put out a significant amount of force without tangling the derailleur in the spokes.

All the force should be applied to the top of the freewheel or cassette, and not to the derailleur.

Cross-chaining would tend to pull the derailleur away from the spokes, but even on the small front sprocket, it should be slightly to the outside, and not pull the derailleur towards the spokes.

So, there is nothing that naturally would pull the derailleur into the spokes.

Lacing the spokes, the cross should be so that the pulling spoke is on the outside. So, under strain, it straightens the spoke, pulling it further away from the derailleur, and that appears to be correct on your bike.

So, that all gets you back to either a sloppy loose derailleur, or a derailleur out of adjustment (or both). Problems of a derailleur into the spokes often happen when climbing because that is when people are shifted into the large rear sprocket, and thus the derailleur is closest to the spokes.

One of the reasons that road cyclists don't really like the little plastic discs behind the freewheels/cassettes is that a properly adjusted derailleur never drops a chain off of the cassette, nor puts the derailleur into the spokes. NEVER.

Oh, dropping the bike on the derailleur can bend he derailleur hanger or derailleur, and cause it to go into the spokes too

ghostamongyou

Some of what you've said there, I'm not yet knowledgeable enough about bicycles to understand. The gist of your message though seems to be that the rear derailleur was likely out of adjustment somehow. When I get the bike back from the shop this week, I'll try to do some more reading up and youtubing on rear derailleur adjustment.

I do know this though: when mounting the back of the bike on a stand to adjust all the gears and index them a few days ago, everything worked properly. Going through the full range of gears, from lowest to highest and vice versa, multiple times, nothing was off or out of sync anywhere; everything was smooth as butter. And I didn't have any problems after a couple of near hour long rides. And yet... upon hitting that steep incline and trying to stand and power through it, catastrophe happened. I'm not honestly not sure what I can do differently.

InTheRain

A similar thing happened to me. The derailleur ended up in my spokes because the carbon drop outs where the derailleur hanger attaches to the frame broke/failed. It's my understanding that the hanger is designed to break... not the frame. After some complaining and negotiating my LBS went to bat for me with cannondale and they replaced the frame.

I have come to find out that an improperly installed/aligned rear derailleur can put a lot of stress on the frame. However, you should notice some difficulty shifting immediately if that is the case. It happened on my replacement frame. The LBS built up the new frame with a combination of my old components and some new/replacement components. I noticed some pretty rough shifting on my first ride. I took it back to the LBS and one of the mechanics checked the alignment of the derailleur to the frame and rear wheel. He was rather embarrassed that it was out of alignment but got it fixed right away.

Kind of made me wonder... "was this the issue with the old bike?" I had never worked on it (lifetime free adjustments) but the LBS had done numerous adjustments over the years. However, I can't say that I noticed any rough shifting on the old bike when I had my frame/derailleur failure.

Trevtassie

More than likely a combination of several things. Derailleur slightly too close to the spokes, wheel flexing from climbing, cheap derailleur. Get a Deore derailleur and make sure it's adjusted right and get a reputable LBS to check the spoke tensions.

dabac

Far more likely to be the other way around.


The derailer sits on the slack run of the chain and doesn't see much force while JRA.


It'd take a serious production/quality issue or earlier damage for a dropout to break while JRA unless something else happens first.



That is the intent, but it doesn't always happen.


I doubt to which extent - if ever - dropout/hanger combos are tested to verify the intended sequence of damage.


I've "rescued" a Scott once by adding a small wedge to the replaced hanger to compensate for a warped dropout.



A nice and logical outcome that I wouldn't take for granted.
If a sacrificial part fails by not failing and causing further damage due to that, I'd consider that a design/manufacturing flaw. Like an electrician installing over-rated fuses that enables overload damage to occur further down the line.



Don't think so.
RD's sit on the slack run of the chain. They can't put much force on the frame unless they either get caught up in the wheel or the lower run of the chain goes taut. Lower run going taut can happen due to chainsuck or the freewheel/hub seizing.



Don't forget slop. RD's have several joints and pivots. They're not all equally exact to start with, and go sloppier with mileage. I've retired several derailers due to pivot wear making them lean dangerously close to the spokes.

ghostamongyou

Someone else mentioned upgrading the rear derailleur also, so I'll get with my LBS mechanic about it to see how much more it'll cost me to upgrade to something better.

I took a peek on amazon at 'Deore rear derailleurs', and I'm not sure which one I'd need. My bike is a 21-speed with three cogs on the front, seven in the back, and twist shifters. Any idea what would be the appropriate rear derailleur for that setup?

Trevtassie

Something like this Shimano Deore M591 9 SPD Rear Derailleur > Components > Drivetrain > Rear Derailleurs | Jenson USA Any Shimano 9speed speed Long Cage (SGS) MTB derailleur will do.

ghostamongyou

Hmm, ok, so a 9-speed derailleur will work for a 7-speed rear also and I don't have to specifically shop for a 7-speed rear derailleur? Good to know. Learning more all the time... thanks.

rgconner

One more way to put a twist on that rear derailleur: Kink in the chain.

A jammed link can put a sudden and severe strain on the rear derailleur as it fails to negotiate the jockey wheels.

Check the condition of your chain, see if it has any sticky links.

ghostamongyou

I see your point but am confident the chain was fine, with 'was' being the operative word there. After all the yanking around on it I had to do to get the derailleur pulled out enough so I could free wheel the bike back to my car, my LBS will be going over it.

StanSeven

I cleaned up the thread and deleted the excess posts.

It's too late now but a suggestion to reach ten posts is go to the Introductions section and greet people

ghostamongyou

Excellent suggestion for future reference! I'll try to keep that in mind on any other forums I may join that have similar post requirements. I wish I had thought of it.

JReade

I always assumed the protective disc was there to prevent the overshifting. Looks like it was about the same size as the mega range gear.

Beachgrad05

I had my rear derailleur into my spokes recently and I did hear the tink tink tink noise but was not thinking that was issue. It was a new sound. Thought I might have loose spoke which I've had before that resulted in similar noise. Or wheel magnet was hitting sensor tho when off bike spinning the wheel could not reproduce sound so was not aware derailleur was hitting spokes.

Got to hill and shifted into granny gear and kaboom derailleur grabbed spoke and snapped dropout off as well as the hanger. Trek was not willing to warranty as it was likely not frame failure that caused issue. I posted a thread here.

NoGears

Flexed wheel and/or poor adjustment. I stand and mash often on steep hills (as much as 23% grade once but often 10-15%) and I weigh a lot more than you and have never had anything like that happen.