shelbyfv

I think most here would agree....

Phil_gretz

"It was a Shimano Tourney TX, RD-TX55 Indonesia."

I assumed this from the OP that said that it was in inexpensive fat bike. Very unlikely that it's Taiwanese made, though. Much more likely Chinese.

The Tourney is an inexpensive model, with two easily bent parts that can cause chain misalignment. The first is the soft steel mounting plate that connects the pivot to the derailleur mounting bolt. Easily bent by hand, much less by any inadvertent impact. The second is the stamped steel pulley cage. The sides of the cage are thin and can be bent, throwing the guide pulley and tension pulley off-plane with the remainder of the drivetrain.

The OP's diagnosis may be partially correct. If the pulley cage gets bent enough, the tension pulley can be offset laterally inward, putting side pressure on the guide pulley as the chain meets it. This problem can mostly be corrected by hand bending the cage back into alignment. The better solution is to replace with any higher level non-SGS derailleur. Choose one with a thicker stamped pulley cage plates. Even the M360 would be okay in this application. Of course, the chain should be replaced.

70sSanO

Keep in mind that there are people in this sub-forum that are paid mechanics, some have worked on pro cycling teams, for bike manufacturers, and owned bike shops.

You have come here espousing great knowledge and riding ability, yet you went to a mechanic to shorten your chain so you could ride your bike home as a single speed.

John

pdlamb

If I can circle back to the assumption that the spokes are still OK -- I suspect that's a bad assumption. At the very least you need to carefully inspect all the drive side spokes and look for scratches from the derailer. Any scratches will act as a stress riser, leading to accumulating fatigue and, eventurally, failure. They may not fail tomorrow, but in a few months you may be plagued with a succession of broken spokes. (Been there, done that!)

Kai Winters

Wow !
I 'was' offering suggestions, etc. based on the the original post.
I am terribly sorry I took the time and effort to offer serious suggestions, etc.
I've seen this problem often enough and have repaired them in over 20 years of wrenching...including today.

I'll not bother wasting my time, energy or effort again...

SoSmellyAir

Please limit that to posts by Alo.

Prior to this pandemic, I have almost always let my LBS handle any mechanical issues. However, that practice has proved to be pretty much unworkable during this pandemic, so I have learned quite a bit from YouTube and the advice on these forums.

rosefarts

Stiff link caught the derailleur and bent it over. No design flaw, just a buggered up chain.

With all his bluster, does the OP know how to check that a derailleur hanger is straight? It’s certainly not a matter of eyeballing unless it’s severely damaged.

alo

I am heavy, and take bikes on rough trails. I have broken spokes on other bikes.

I have taken this bike many more kilometers on rough tracks than any other bike. I have been surprised spokes have not broken. This is a tough bike. With some bikes, I would have had to replace wheels several times if I took them on the same tracks.

I have broken the rear axle on this bike.

Even ripping the derailleur apart, spikes did not break. The derailleur is fairly weak construction, and broke fairly easily.

Maybe spokes have been weakened. Maybe not.

It is likely that the time will come when a spoke breaks, and it may not even have anything to do with the derailleur issue.

In the past, I have only ever had one spoke break when it first happens, and I have always been able to ride home with one broken spoke.

So I will continue to have fun, and wait and see.

Many other people would stick to smooth roads, and be gentle on their bike.

I will continue to take mine anywhere.

More things will break in the future. It is just a matter of what breaks and when.

alo

It is interesting the number of people who take their bikes to shops for repairs, and the people who feel they have some sort of moral obligation to support their bike shop.

With internet sales continually increasing, many bike shops will not survive, and you going there will not save them. So don't think you can.

In Australia, I have never taken bikes to anyone for repairs. If I took bikes to shops for repairs several times, It would cost me more than I have spent on bikes in my entire life.

In S E Asia where I am, many people are poor, and I like to support them. I have had two punctures repaired recently. I paid US 50c and 75c for these. I had my chain shortened for 50c.

If I had all my repairs done at shops here, it would not cause financial stress.

Those who don't know how to repair bikes, I suggest you learn. Many bike shops will not be there in years to come, and you may have to do it yourself.

shelbyfv

Well friend, this is a bizarre tangent. AFAIK, nobody in this thread, other than yourself, has evidenced inability to repair their bike. Hope you get back on the road soon, regardless of who fixes the bike.

CliffordK

There seems to be a strong call from a lot of members to take the bike to a shop. I.E. Is that what these "experts" expect should be done in all situations?

A derailleur replacement is not that hard.

A hanger alignment tool can be handy, but one may be able to get it close enough with an adjustable wrench and eyeballing it. Use your derailleur as a guide... well, a good derailleur. This bike isn't being taken on the TDF.

veganbikes

You buy the cheap-o derailleur and think it is a design flaw and then go on a rant about bike shops needing to die off and we don't need to support them...yeah as they said in the Simpsons: "You don't win friends with salad"

Tourney is not designed to last it is designed purely for a price point. It is cheap and designed to be cheap and not so good because if it were excellent you wouldn't need higher tier stuff. Plastic and cheaper stamped parts aren't going to last especially not under heavy riders and a lot of usage especially off road. Probably the only time I might run tourney is on a little kids bike they are going to grow out of quickly and not ride often but my kids if I ever adopt would be riding on much nicer stuff (probably out of the parts bin)

The fat tire bike was probably made in China or elsewhere with cheap labor. It could have been made in Taiwan but usually that is reserved for higher quality bikes. It could even just be some rebranded Mongoose Dolemite or close to it.

In terms of broken spokes those are common on lower quality machine built wheels that don't really see human hands especially on heavier riders. Machine built wheels can last a bit longer under a heavier rider provided that they were tensioned by skilled human hands after they came out of the machine and are using decent quality parts. My Quality Wheels made with Alex rims and Deore with DT Swiss spokes have been fantastic but they are hand tensioned after they are built. A lot of the cheaper Wal-mart style bikes aren't touched by any real skilled labor in the process.

CliffordK

Back to the bike...

Try a Shimano Deore M591 or M592 if you can get it. New chain. Straighten the derailleur hanger. If shop rates are cheap, the shop should have the right tools. Otherwise, you can improvise if you wish.

The M591/M592 cages should be much better than your Tourney. But, you could take a file and round the inner plate corners if you wish, it wouldn't hurt anything, although hopefully not necessary.

I think the M662 and M771/M772 are also good. Perhaps the M662 is available.

How bad are the jockey wheels worn on your derailleur. Upgrading and hopefully the jockey wheels will last much longer.

smashndash

Ok I sorta knew where this thread was headed before I even read it. Classic blame the user, millions of bikes are fine, never happened to me, you must be dumb.

This exact thing happened to me (I think).



I was doing cadence drills. I can easily top 200rpm and I've done it several times. But this time, when I stopped pedaling, my chain made a noise. I assumed the chain had dropped, so while COASTING I looked down. Chain was still on the little ring. So I tried pedaling forward. BAM. Rear mech went into the spokes. Note that I was coasting this entire time. The derailleur was pushed by the pedal torque into the spokes. The chain had probably gotten derailed off the jockey wheels due to the high rpm.

I refuse to take even one iota of blame for this. It's a design flaw. I'm not saying that OPs problem is necessarily the same as mine, and it is odd that it happened at a lower rpm. Admittedly, most people don't do 200rpm cadence drills.

I'd say something like "maybe bf members need to learn to keep an open mind" but I'd be more likely to solve cold fusion.

70sSanO

One of the more bizarre threads in a while.

John

Geepig

Well, the difference here is that you have given enough information. The OP does not appear to be interested in any solution, discussion or whatever, and has received the aggressive response their aggressive approach was always going to generate.
As an engineer I am fascinated how the chain and pulleys responded when you switched to coast. I often watch the chain move around when I have a bike upsidedown, for example, and last night I had one with a few stiff links that would attempt to jump the sprockets.

CliffordK

Interesting.

I think I've jumped the jockey wheels a few times. But, never spun the derailleur.

In my case, I think it had to do with several things.

• Gear capacity close to derailleur max... thus chain was low tension on small/small.
• Cross chaining small/small (prepare for short, but quick hill climb)
• I suppose it is possible that I also hit a shift without pedaling. It has been a while since I've had the issue.

I don't think the skipped chain was immediately obvious.

nomadmax 

That may be true.

But it isn't our bikes that are broke...

alo

I bought a bike, and the derailleur was on it when I bought it.

alo

Thanks to the decent people giving genuine responses. I wont comment on all of them, but it is good to see genuine people on this forum.

alo

I believe in my case, the jockey wheels were worn and wobbled, which allowed a chain link to catch on the derailleur.

In future I will be aware of this, and replace the jockey wheels when they are worn too much.

alo

I have now fitted a new derailleur and chain, and my bike is like new again.

The derailleur cost US$2.25

The chain cost US$1.40

I actually bought two of each, so I have a spare at home, either for my bike, or if someone else's bike needs repairs.

These are made in China. Brands that most people in other countries would never have heard of.

The derailleur looks like a plain budget derailleur. The metal is thicker than the Shimano it replaced, making it look stronger. It is a sad day when a US$2.25 derailleur made in China, is stronger than a brand name derailleur.

The jockey wheels are also plastic, so will probably need to be replaced some time. If I have to buy another US$2.25 derailleur every six months or year, just for the jockey wheels, it will not cause financial stress.

I don't expect this derailleur will break with normal use. But with what I do, there is the risk or falling the bike, or knocking it on a rock, or something else. I don't consider anything on my bike to be unbreakable.

Where I am, the concern is not the cost, the concern is being far away when something breaks, and the inconvenience that may cause.

I am sure a lot of people in America, would like to buy parts at the prices here.

Koyote

So, to recap: You believe that your old derailleur was faulty, so you replaced it with a $2 derailleur.

Yeah, that'll be a big upgrade.

alo

and the $2.25 derailleur is stronger. I believe it will never break from regular use. Of course there is a possibility of getting knocked or something, which could damage it. It is one of the derailleurs they normally use on those everyday ordinary bikes, used for transport, not sport.

alo

It seems to me, a few decades ago, derailleurs and chains and sprockets were designed to last the lifetime of the bike.

Most of the modern ones are designed so they will fail and need replacing. So the company can sell more, and make more money.

Everything is made to be broken.

The $2.25 derailleur appears to be like those old style ones, designed to last the lifetime of the bike. Except it has plastic jockey wheels, which will need replacing.