kwyer

I may have a new twist on this situation of broken chains on new bikes and destroyed deralliers. Its a bit complicated but hang with me and do your on research to verify. Recently purchased a new tandem bike and the wife and I were on our first ride at about mile 25 on a short climb the chain broke and took out the derallier and the hanger. Frame must go back to the factory. Carefully inspecting the chain I found a chain pin(smooth on both sides with no indent on the push side or break-off mark on the back side) that I was not familiar with as the chain was a HG-93 with which I am familiar. First thought was that the bike shop used the wrong pin. Called them and that said they see this same pin on bikes that come in from manufactures with the chain already installed. Called the manufacturer on this specific bike and ask them how they ship to the dealer. They said they ship a bare frame with a build kit including chains so dealer had to put the chain on this bike. Went back to the technical paper on this chain on Shimano's web site(go look for yourself at www.shimano.com) and found a graphic which indicated a type of pin called an "end pin" which appears to be somewhat smooth on the side versus indented like a normal link or a regular connecting pin. Called Shimano and ask them what was an "end pin". The said that it was an OEM connection pin to be used only by manufactures with a special impact gun to set the pin and a normal screw type chain tool will not install it properly and flare it to securly set it in place. So it looks like the bike manufacturer passed an OEM chain with and end pin on it(it comes already attached to one link for installation speed) and the dealer thought they were supposed to use it and popped it in with a regular chain tool. Whew! You and I and bike shops are never supposed to have OEM chains or the special impact tool gun to install them. So, bike manufacturer is currently talking to Shimano to get the final ruling on this situation and to see if they have been passing OEM chains down when they should not have. They were not aware of this situation. I talked with two of the best bike shops around town and they also had no info on and end-pin. This would explain chain failures early after purchasing a bike if the shop installed an OEM chain. I myself will never ride a bike with and "end pin" again as this will cost me about $500.00 dollars when its all said and done. I had previously built all my bikes up from the frame and installed all my own chains purchased in retail packaging and had never had a chain failure in over 8 years and 10 different bikes. Check your broken chains and look to see if it fails on an "end pin".

cascade168

Hmmmm, an interesting thread ...... I am a firm believer in Occam's Razor - that being that the simplest solution is, more often than not, the correct one. One thing that nobody has mentioned here and something that I feel may be key is that are you absolutely sure that the high limit screw is set properly?
The ultimate test of this limit screw setting is shifting while going up a hill. If you are in high gear at the bottom of a hill the load on the derailleur is at it's greatest and that little screw is all that keeps the chain off of the dropout. Just a thought. I may be totally wrong, but I don't see anyone else questioning this.

kwyer

Agree with you about the possiblity of the limit screws being a problem, but in our case I was very careful to assess the bike when the incident happened and was in the 5th gear in the rear on a 9 speed cassette.

LóFarkas

I buy into the chain pin theory. What boggles my mind is that you are not supposed to break a shimano chain and then put the same pin in again. Apparently, that is why they make the end pins. But if you can't install an end pin with a normal chain tool, either, I can't see how anyone is supposed to use a ****mano chain at all. Of course, they don't make something like the powerlink, so you can't even get your chain off for cleaning, let alone shorten or install from the box.

Bottom line: do not use a shimano chain.

spleck

kwyer, Can you either tell us, or hint to us the name of the manufacturer? I broke my derailleur hanger last week. I had some rough shifting, a little extra tension pedalling, some chainsuck, I may have back pedalled a little, then on the next push my derailleur was swinging almost to the ground. I was in the middle of the cassette, so it wasn't a limit issue and I don't think I had any damage to the spokes. I haven't really inspected the derailleur, but the chain was ugly. A plate was cracked and bent so I'm guessing it caught on the derailleur and pulled it up. I'll have to check to see if the pin was any different than the others.

I had to order a derailleur hanger directly from Specialized because my LBS didn't have any in stock and told me it would be $20 to get one. So after ordering 2 at $12.95/each, the owner of bike shop emails me to say that they DO have one and its only $12.99. Anyways, once I get it installed, I'll probably have them check out my frame because I'm afraid the screw hole for the hanger is also bent.

By the way, I only have 45 miles on this bike...

kwyer

Don't want to put their name out here because they are being great about the issue and are being very aggressive in doing research to correct the issues. I will say that they are not one of the big boys and that is paying dividends here because I doubt that any of the big boys would be working with me like this manufacture is doing. After we get resolution I will post a follow-up and name the company if they are OK with that.

Chris2fur

Hey, I think you may have missed something in kwyer's post--the "end pin" he mentioned is not the same as the repair pins that you are supposed to use. If you read the post again, you'll see that the "end pin" mentioned has smooth ends (no indent where the pin gets pushed and no "break-off" rim on the other side). He stated that the end pin was mistakenly used as it takes a proprietary power ("impact gun") tool to set it. It should have been removed and the proper repair pin used if they didn't have the power tool. Anyway, I agree with your conclusion (I use Sram chains). If I were going to run a Shimano chain, I would still use a Sram Powerlink.

2manybikes

That's correct, once you take a pin out of that chain you cannot use it again, It needs to be replaced by a "replacement pin". The replacement pin is NOT and "end pin" at least that's not what Shimano calls it on the web pages that explain it or the instructions that come with the pins and the chains. It is what bike shops and bike owners use to connect chains. When you use one there are no problems, I have a couple of bikes that have thousands of miles on them with those pins that I put in, and have put chains on quite a few others that are going strong. If you use Shimano replacement pins you can shorten or connect chains any way you want to without problems.

I went to the shimano page that explains how to install a "reinforced replacement pin" It does not explain an "end pin" but it shows one from the side so that you can identify one if you are working on a chain. It's in the diagram of the side view of the chain on this page.

https://cycle.shimano-eu.com/media/cy...9830558543.pdf

jur

The chain snagging in the cage of the derailer does seem to be the best explanation:

In the OP, it was stressed the derailer bent *outwards* each time. As far as I can reason, there is only one way this can happen:

1) The derailer parallelogram geometry is such that the mech is moved diagonally, inwards&down [edit] OR outwards&up [edit].

2) The only place there is tension on the chain is on the top part between the front and back sprockets. The bottom is held under tension by the derailer itself, so the only force on the derailer is coming *from the top*.

3) If the derailer did NOT go into the spokes, then the ONLY way to mangle it, is by the part of the chain trailing over the back of the cassette through the derailer, since this is the only place for the origin of force, assuming there was no chain suck.

4) If the chain somehow got snagged on the derailer cage, it would pull the cage upwards. Due to the parallelogram geometry, this will force the cage *outwards*, and worsen the propensity to snag due to misalgnment.

5) This can happen if you shifted to a bigger gear; the bottom part of the chain is under low tension so swings from side to side a bit while shifting, increasing the likelyhood of snagging.

6) Cheap derailers would be more susceptible to this due to the poor tolerances in the various hinges.

7) Although dodgy pins would make this scenario worse, a derailer cage with sharp edges and loose pulleys may also be susceptible. It would only take a small initial snag to increase the chances for a bad one.

supcom

Don't brand new tandems come with warranties? Seems to me that whether the manufacturer or the bike shop screwed up is not your problem. There was obviously a defect in material and workmanship that should be fixed at no charge to you.

chemcycle

How?

Seems to work fine under load uphill for me. Can't say the performance is any better than a "normal" one, since I've had "rapid rise" on my MTB for quite awhile.

Al1943

A similar thing happened to a friend's road bike. Tight link in the chain hit the rear derailleur, ripped it right off the bike, pulled the dropout off the chain stay and bent the seatstay. Chain had been cleaned with a power washer and not properly lubed. Check for tight links in chain.

willett

yeah your stops slipped mr.holms, and your derrailler ended up in the spokes

kwyer

Follow-up to my story above. Bike shop(Park Ave Bikes, Rochester, NY) and tandem bike manufacturer(Co-Motion, Eugene, OR) did a great job of dealing with this situation and we have our tandem back and it has even been updated with a newer dropout design that they are putting on new tandems. They did not just fix the busted dropout but replaced the other side so they would match. Kudo's to these guys and there customer service with this situation has already caused some others in our bike club to decide to go with them instead of another brand. Give these guys your business if you are looking for a tandem or regular bike. Their bikes are made in America by great people so check them out at www.co-motion.com

As for the chain, I installed the same type of chain(Shimano HG-93) back on the tandem bike with the normal "re-enforced connecting pin" that comes with a retail chain and we have had no problems at all for a couple of hundred miles. Shimano still claims that you can connect a chain using an "end pin" with an HG compatible chain tool with no problems but they have not been able to produce any technical documentation that specifically states this and I do not trust their stance at this point. I am very happy with a Shimano HG-93 chain joined with a "re-enforced connecting pin" and have this same chain on five different bikes with no problems, but I will never ride a bike with an "end pin" in it again and recommend that anyone with a chain with an "end pin" used to join it should get it replaced with a "re-enforced connecting pin".

kwyer

Follow-up to my story above. Bike shop(Park Ave Bikes, Rochester, NY) and tandem bike manufacturer(Co-Motion, Eugene, OR) did a great job of dealing with this situation and we have our tandem back and it has even been updated with a newer dropout design that they are putting on new tandems. They did not just fix the busted dropout but replaced the other side so they would match. Kudo's to these guys and there customer service with this situation has already caused some others in our bike club to decide to go with them instead of another brand. Give these guys your business if you are looking for a tandem or regular bike. Their bikes are made in America by great people so check them out at www.co-motion.com

As for the chain, I installed the same type of chain(Shimano HG-93) back on the tandem bike with the normal "re-enforced connecting pin" that comes with a retail chain and we have had no problems at all for a couple of hundred miles. Shimano still claims that you can connect a chain using an "end pin" with an HG compatible chain tool with no problems but they have not been able to produce any technical documentation that specifically states this and I do not trust their stance at this point. I am very happy with a Shimano HG-93 chain joined with a "re-enforced connecting pin" and have this same chain on five different bikes with no problems, but I will never ride a bike with an "end pin" in it again and recommend that anyone with a chain with an "end pin" used to join it should get it replaced with a "re-enforced connecting pin".

doctorSpoc

I ripped my Dura Ace 10spd rear derailleur off at the hanger just a few weeks ago. The problem was that the screw that held the removable hanger to my frame was loose and I probably didn't torque my rear wheel's quick release enough. I think this allowed the pulleys to go into the spokes. Heared tick, tick and skidded to a hault up a nice big hill. the derailleur went into the spokes, chain jammed behind the cogs of the casette and twisted and broke. I put lock tight on the hanger screw now so it can't get loose.