CliffordK

A little more about the OP and his goals would also be useful.

The Roadies out there tend to drop the fat bike riders (except the fat e-bikes) mighty quickly on pavement.

If this bike was part of diet and exercise, and he is meeting those goals, then there are a wide range of bikes out there that may also meet the needs including FAT bikes, MTBs, Cyclocross, Gravel, Touring, Cargo, and Road bikes, depending in part on what kind of roads and trails are the preferred destination.

70sSanO

Since the the premise of this thread is a derailleur design flaw, contact Shimano and point out that flaw in their design. I’m sure there are people in their engineering department who would be more than happy to hear from you.

Obviously you had hoped for more support here, or you wouldn’t have started this thread.

John

cxwrench

Pro racers don't 'choose' anything. They ride what's on the bike that the mechanic gives them. That decision is made much higher up the chain of command and at the Pro Tour or World Cup mtb level is obviously going to be the top of the line so there really isn't a decision to be made.

SoSmellyAir

Your original post has no photos or any other indication of (1) the model of your bike, (2) the model of the component at issue, (3) what you have done to try to fix it before concluding that there is a design flaw with that component.

Having very little information (see above) to go by, Trakhak posits a potential issue that -- in hindsight, based on your alleged level of mechanical abilities -- seems obvious, even though you also stated that you had not looked in detail at that issue because it had never happened before and thus was not something you expected. So, perhaps not really that obvious, certainly not so obvious as to cause immediate offence or to be construed as calling you stupid.

I humbly venture that responding with such a suggestion is also obviously expected given all the unknowns, but then again, I am not overly sensitive.

Or should we all adopt the Japanese way of conversing in the passive voice with no pronouns lest someone gets offended?

CliffordK

Would you ride on a team that gave everyone $100 Walmart FAT bikes to do a 100+ mile paved road race?

Wider the better for tires, right? That is what I keep reading here.

No doubt companies make more money selling Walmart FAT bikes than selling $10,000 road (or MTBs), so wouldn't it be better to use what they are selling....

Except they also want to win, not show a bunch of riders left in the dust.

Koyote

The OP‘s theory is defective – not the derailer.

JohnDThompson 

Agree that these are the most likely causes. And if the hanger wasn't bent before the incident, it almost certainly is now. OP should check hanger alignment before installing a new derailleur.

SoSmellyAir

OMG are you calling the OP stupid!?

alo

I am in S E Asia, where bikes are much cheaper than in places like America. I have looked on the internet to get an idea how much the same bike would be somewhere else, and have been unable to find the same bike.

The bike is an X-treme 26 inch fat bike.

The X-treme bikes I have seen on the internet are electric. The X-treme bikes they sell here are ordinary pedal bikes.

It has a strong frame, which will probably never break. With what I have done with it, I am amazed I haven't broken spokes. So the bike is tough. I have ridden thousands of kilometers on very rough tracks.

Replacement parts are very cheap here, so repairing it is not a problem financially. The problem is if something breaks when I am somewhere far away, and the inconvenience.

I don't believe there are any better quality fat bikes for sale here.

If there was, an expensive bike may break as often.

Some people look after their bike, by avoiding the worst places. I don't avoid going anywhere. If it breaks it can be repaired. Replacing the entire bike is also cheap here.

alo

It is impossible to know for sure, and the derailleur is totally destroyed, so it cannot be reproduced. But I think it was most likely the leading edge of a link that caught on the derailleur.

Prior to it happening, it did not look bent or out of alignment, and worked fine, but something was obviously not right for this to happen.

JohnDThompson 

Don't confuse "stupidity" with "ignorance." If someone isn't aware of the possibility, they may not consider it when replacing the derailleur.

SoSmellyAir

I am aware of the distinction between stupidity and ignorance; I was facetiously referencing a similar suggestion by Trakhak (to check the rear derailleur mounting tab), which the OP construed as Trakhak calling the OP stupid.

philbob57

1) A failure in an instance of a device does not mean the device was poorly designed.
2) Clearly something was going wrong with the drive train, but alo kept riding instead of diagnosing and resolving the problem. Then the derailleur went into the spokes. That means the derailleur was damaged beyond repair, but it doesn't mean the der itself failed, and if it did fail, it doesn't mean that alo figured out the source of the failure.
3) Alo thinks he can evaluate the hanger without a mechanic's help. That's up to him, as was continuing to ride when he knew his drive train was not operating as expected. But no one knows everything, and sometimes specific knowledge is a hell of a lot more important than intelligence. I'd want a 2nd opinion on something like this myself, but I think lots of people would make a different choice.
4) Many years ago, a reporter for a certain magazine listed the 10 dumbest members of the US Congress. The person identified as the dumbest called a press conference to announce that he wasn't the stupidest boss. He did not get a positive reception. The moral I drew from that story is that declaring oneself to be smart isn't smart. Show, don't tell.

Kapusta

Did I miss the part where the OP said what rear derailleur he had?

Litespud

Actually the advice to take it to a mechanic was spot on. Anyone who claims that they can confirm that a hanger is straight by eyeballing it is deluding themselves. You might tell if it’s well bent, but that’s it. No way can you tell if it’s a few degrees off by eye. A shop will have the correct tool to properly check straightness. Unless you have the gauge/straightening tool yourself of course, in which case, a reasonable response might have been “yes I’ll check the hanger - no need to go to a shop, I have the appropriate tool at home”
Try to a little less of a dick to people giving you advice when you came looking for advice 👍

Geepig

Even if totally destroyed a good engineer can often see the chain of events, which is one of the reasons for posting pictures.

I wish you luck with the bike.

nomadmax 

I'm a Campagnolo man right down to my tattoo. But it's pretty hard for me to believe a Shimano RD killed itself because of "design flaw". Truth be told, if it weren't for Shimano, Campy would still be selling old NR/SR rear derailleurs with pulleys that cracked.

ARider2

Another possibility is debris got caught in the chain causing it to jam in the rear derailleur, or the chain itself was damaged causing it to jam.

alo

Maybe I was wrong. Maybe a lot of people on this forum don't have a good understanding of mechanics, and need to take their bike to a mechanic when something goes wrong.

alo

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

Kai Winters

I've a few questions and some suggestions.
When has the bike been serviced? You say you've been riding the bike for 2 years. Has the chain and cassette/freewheel been checked for wear and stretch?
You say the chain was a bit loose and would jump teeth...this is a possible sign of a stretched chain and possibly worn cassette/freewheel. The chain will skip over the teeth as it tries to bite the gears. The springs in the rear derailleur do their best to keep tension on the chain to prevent 'chain wrap' but a stretched chain, worn gears, bent rear der. hanger and an inexpensive rear der. whose spring has lost some of its' strength are a combination recipe for disaster. There is also the possibility that a stretched rear der. cable, out of adjustment due to stretch over time and not checked and adjusted periodically could be a contributor to the problem.

My suggestion: Bring bike to LBS...explain what happened...A good shop with check chain stretch, gear wear, hanger alignment, cable stretch/rear der. adjustment, etc.

The limit screws and "B"/chain wrap adjustment on the rear der. should not have 'moved' on their own accord...they just don't move...but the limit screws won't do their job if the rear der. hanger is bent.

Sounds more like the rear der. springs were under load, tried to do their job then failed to do so and chain wrap with damaged parts is the result.

If you want good info, suggestions, advice you need to tell us the name of the bike, model of the der., etc. otherwise we are just guessing.
Good luck.

shelbyfv

You may be on to something there So it is/was a Tourney derailleur, that's helpful

. From another thread, this is your bike but it doesn't seem to have fat tires. Is there another bike? Maybe post a pic.

alo

You are either not reading, or ignoring, or deliberately misquoting what was said previously.

After the derailleur failed, I had the chain shortened, so it became a single speed, and I could ride home.

Then somebody suggested.

As a single speed, with no derailleur, I explained the following.

You are implying this was before it failed.

If this is a genuine misunderstanding, go back and read previous posts.

If you are intentionally misquoting, don't waste your time.

You can also read previous posts for the make of the bike and the model of the derailleur.

alo

Does this look like a fat bike to you?

Maybe read some of the previous topics, where I have discussed some of my other bikes.

alo

Many people do tend to think other people are like themselves. Those with a poor understanding or mechanics often think others also have a poor understanding. I assumed that most people on this forum had a decent understanding of mechanics. Maybe I was wrong.

I like to treat people like they are intelligent, unless they say or do something which indicates they are not.

None of us know it all. That is what forums are for. To share ideas with others, so we can all learn.