Bicycle Mechanics - Why did my chain break on my new bike?

I have a raleigh 24 speed mountain bike (front shocks only) that is about 6 months old, but I didn't start riding it every day until about 2 months ago (10 miles a day). Yesterday when I was going up a steep incline and pedaling hard my chain broke. This bike was $600 and I didn't really expect something like this to happen so soon... I've seen 20 year old bikes that still have their original chain and have never been lubed. I lube my chain every 2 to 3 rides because I ride along the beach and get a lot of sand in the gearing. Could the sand have caused the chain to break, was I over lubing the chain, or was it just a cheap chain? I use tri flow lube and white lightening lube.

because it is shoved sideways to change gears.. it happens.. to get more gears outside the rear wheel the chain is made thinner, pins flush , rather than proud of the outer plate, like Regina Oro, back when 6 was enough..

It might have been none of the above. I assume yours is a classic chain break where one plate fell off a pin and the other is bent open breaking the chain.

Nothing you did with regard to your chain care caused this, it most likely is from one of two common causes.

1- bad closure at the factory. This might be one of the most common reasons for chain breakage. The people on the assembly line close hundreds of chains daily, and sometimes fail to make sure that the pin is through both links and centered properly. If you sill have the damaged link, the giveaway is a bulge on the inside of the outer plate that came off the pin (not the bent one still attached). That shows that the end of the pin being pushed through wasn't lined up and bent the plate before find and going through the hole.

2- bad shifting. Hard shifting under load with a modern index system is incredibly destructive to chains. They can withstand hundreds of pounds of tension, but when twisted while half engaged on two sprockets is very stressful. When you shift under load the chain is forced tighter into the twist and the link's are pried apart eventually coming to the end of the pin. The chain is now weakened but can continue to work for days or weeks until a high load is put on it on a steep hill, then snap. It's the same way a rope that's been frayed won't break until stressed to the max.

The second is a common cause of chain breakage among new riders, who tend to shift too late, and are forced to try to shift under load. Try to anticipate your shifting and shift while you still have enough forward momentum to lighten the pedal pressure through the shift.

Normally I try not to shift under load, but that must have been what happened. I will have to look for a higher quality chain that can take a litte more abuse.

There's no reason to shop top of line. Any chain from the mid range on up in each manufacturers line will do you. After that more money buys less weight or nicer finish but not more strength.

BTW- depending on the rest of the chain's condition, you might be able to repair it by cutting out the damaged outer link and replacing it with a connector from Sram, Wippermann, or KMC. Just be sure to buy the right width.

+1 on FBNY's comment. Shifting underload = :cry: chain.

BTW- depending on the rest of the chain's condition, you might be able to repair it by cutting out the damaged outer link and replacing it with a connector from Sram, Wippermann, or KMC. Just be sure to buy the right width.

+1. If you do go with a new chain, be sure you install it per the instructions. On many new chains, once you've pushed a pin out, you can't put it back in because the holes on the outer plates get enlarged. Either use the special connecting pin on Shimano chains or a connector link on other chains (including Shimano). On my MTB commuter, I use a Shimano 6,7,8-speed chain and KMC 8-speed connector link.

Could have been a bad chain / bad pin / poor assembly. Had to replace mine this year, but it wanted to jump gears when stomping on it. At lower force all seemed well. You could see that the link was funny precisely at the joining pin. LBS just swapped in another one. Lucky it didn't snap open on me.

The wider chains for older 5 / 6 speed clusters were more robust and more forgiving. You could almost open and close those things all day.

The old chain is in the trash so I'm definitely getting a new one, probably Shimano because I trust that brand. Does a lighter weight chain really make a difference, or is it only for people who race in competitions?

Lighter chains aren't about competition. They're for showing others that you have more dough to spend on chains. Buy any of the mid level Shimano chains, but make sure you have the right tool to close them, though many use Sram links on Shimano chains

Lighter chains aren't about competition. They're for showing others that you have more dough to spend on chains. Buy any of the mid level Shimano chains, but make sure you have the right tool to close them, though many use Sram links on Shimano chains

The new shimano chains have only *recently* trickled down to the 105 groupset. Before you could only get ultegra/dura ace chains with the new improved design.

I ended up using an Sram chain because the shop didn't have an 8 speed Shimano and the shop was having a sale on the Sram. With this new chain my bike seems harder to pedal than before... like I can't accelerate from a stop as quick. Is this possible or is it just in my head?

Check that the chain isn't dragging on something by backpedaling. Next, lift the bike and check that both wheels spin freely and aren't touching the brake shoes for instance. If both tests are negative it's probably in your head. I don't know where you live but it's been hot in New York and that makes everything seem harder.

FBinNY, could you clarify what you're saying about bad shifting? In the old days, it was usually impossible to shift under load. Now it's possible. In fact, it's easy. Are you saying that although it's easy, it's also risky to your chain?

FBinNY, could you clarify what you're saying about bad shifting? In the old days, it was usually impossible to shift under load. Now it's possible. In fact, it's easy. Are you saying that although it's easy, it's also risky to your chain?

Tom, thanks for being the straight man.

Before hyperglide shifting under load was virtually impossible because the moment the chain dis-engaged from one sprocket, and before it would settle into the new one it would skitter across the top and riders rapidly learned that they had to reduse the chain tension during a shift to prevent that.

The gated shifting that hyper glide allows the chain to complete a shift in a short section of arc, so the chain would engage the new sprocket while still attached to the old one, with a sharp S-bend in the transition. It's fine if there isn't too much tension, but as the transition zone comes around the cassette towards 12 o'clock chain tension in the upper loop forces it back down deeper on the old sprocket putting tremendous side pressure on the plates and forcing them out on the pins and/or twisting them, before they finally disengage as they come over the top.

You can see the potential for harm if you put a bike in the stand and do a shift in slow motion and gently hold back the wheel as the shift zone comes over the top.

So while hyperglide (or gated shifting by any name) has been a great benefit to new riders, making unskilled shifts possible, there's a cost in chain breakage.

I've never heard that before, and it's valuable advice. In a way, Shimano has made breaking a chain far easier than before, all so we can shift easily. Perhaps they've gone too far. Breaking a chain is more inconvenient than hard shifting is. It could lead to injury!

And yes, I'm often the straight man, but most people don't pick up on it. When I'm in class, I ask the "stupid questions" because I know what others want to ask but don't want to appear dumb. Or I ask the stupid questions because I sense when something is unclear to others.

Oh, and I hope you don't mind my asking, but what do you think of the KMC Z51 chain? It's inexpensive, and I have to put new chains on a lot of old bikes I work on. So far, so good.

. On many new chains, once you've pushed a pin out, you can't put it back in because the holes on the outer plates get enlarged.


You're right about not using the same pin, but have the wrong reason. Modern chains have the rivets peened over the placed much the same way the ones on steel construction are. When you push the pin through the peened area is sheered off, so when the pin is pushed back through there's nothing to keep the plate from being spread over the end, and falling off.

I've never heard that before, and it's valuable advice. In a way, Shimano has made breaking a chain far easier than before, all so we can shift easily. Perhaps they've gone too far. Breaking a chain is more inconvenient than hard shifting is. It could lead to injury!

And yes, I'm often the straight man, but most people don't pick up on it. When I'm in class, I ask the "stupid questions" because I know what others want to ask but don't want to appear dumb. Or I ask the stupid questions because I sense when something is unclear to others.

When I teach technical classes I start by reminding students that the only stupid questions are the unasked ones. The heroes are the ones willing to say "I don't get it, please explain"

Anyway, it really isn't such a Faustian trade off. Without gated shifting, narrow 9s and 10s systems would probably not exist, and broken chains aren't an automatic consequence. New riders still have to learn to shift, just for a different reason. Having had old Regina chains and freewheels fail to engage when I needed it most before index, I'm kind of happy for the better response, I just don't abuse the benefit.

Fair enough, but like so much in life, there's more to know than ever, just to survive.

Faustian trade off! :lol:

Oh, and I hope you don't mind my asking, but what do you think of the KMC Z51 chain? It's inexpensive, and I have to put new chains on a lot of old bikes I work on. So far, so good.

I'm not familiar with all that many chains specifically, but from what I can see the best value is anything from about 1/3 to 1/2 way up in each company's line. Other than the lowest end offerings all have riveted heads and are probably made from the same or very comparable materials. Spending more might get you better cosmetics or lower weight, but not more strength or wear resistance.

I personally don't ever go 1st class on consumable components. I look for the best function for the buck, and if I ever made a chain you'd have a choice of black or dark black finish since that's what happens anyway.

You're right about not using the same pin, but have the wrong reason. Modern chains have the rivets peened over the placed much the same way the ones on steel construction are. When you push the pin through the peened area is sheered off, so when the pin is pushed back through there's nothing to keep the plate from being spread over the end, and falling off.

FWIW: when Shimano first introduced Hyperglide (1989-ish), they didn't change anything on the chain. This resulted in many broken chains and some really pissed-off bike mechanics. (I attended one- I thought the Shimano rep was going to be lynched.) Shimano rushed out with the special Hyperglide chain and break-off replacement chain pin, which solved the problem. It wasn't until several years later that a real alternative (SRAM) became available.

Shimano chains are designed to deal with the strain of shifting under load. Since the OP's chain broke, I'd suspect improper assembly or sub-par parts.

It wasn't until several years later that a real alternative (SRAM) became available. .

Actually the alternative predated the problem. Bob Lickton invented the Lickton Link some time before that but never succeeded in getting any OEM to adopt it. So it remained a niche aftermarket item used by a relatively small number of cyclists. It wasn't until Sram licensed the patent, (or designed around it) and made the Powerlink standard on their chains that it became common.

I ride with Sram 850 chains on my 8 speed stuff. I got the one above that, and even the one above that and it was shinier, but that seemed to be about it. I've tried the 830 too, but only because the LBS didn't have any 850 in stock.

Actually the alternative predated the problem. Bob Lickton invented the Lickton Link some time before that but never succeeded in getting any OEM to adopt it. So it remained a niche aftermarket item used by a relatively small number of cyclists. It wasn't until Sram licensed the patent, (or designed around it) and made the Powerlink standard on their chains that it became common.

Yeah, I know about the Lickton Link and the Superlink. However, I was talking about a entire alternative chain, not just the link. I don't remember a non-Shimano Hyperglide-compatible chain becoming available until the late '90's.

Hi All, Hi SmoOothride,
Just repaired my 8 speed HG chain with a KMC "MissingLink". The missing link is Shimano compatible.
The part is a nice job. Was easy to repair. It is similar to Sram links.
http://www.kmcchain.com/index.php?ln=en&fn=service
Regards
losi

OK, well, I'm not really looking for the most bang for the buck. I'm looking for the least expensive chain that works reasonably well. I don't want to put a chain on my customers' bikes that has a high risk of breaking. I'll see how I do with the KMC 51 chain. It costs me only $8 from Niagara, which is pretty irresistible.

For my own bikes, I'll buy mid-priced chains, as you advise. And thank you very much, as always.

OK, well, I'm not really looking for the most bang for the buck. I'm looking for the least expensive chain that works reasonably well. I don't want to put a chain on my customers' bikes that has a high risk of breaking. I'll see how I do with the KMC 51 chain. It costs me only $8 from Niagara, which is pretty irresistible.

For my own bikes, I'll buy mid-priced chains, as you advise. And thank you very much, as always.

Nothing wrong with the Z51. KMC calls it a 6/7 speed chain, but it is 7.1mm so will work on 8 speed. May not be the best for performance shifting on 8 speed, but it's a good chain at good value, I used a lot of them as replacements at my shop.

Dan, thank you. That's reassuring. I ordered a couple more yesterday. So far, KMC chains seem to be working out well.