Sasquatch16

Broke my chain last night climbing a small hill. Have done similar and much larger hills in past. Not sure why it broke. Cobbled it back together but derailer hanger is bent and rode the 10 miles home as a single speed very gingerly. I am going to replace chain. What is the strongest 8-speed chain available or are they all the same?

Also at 265 lbs. am I to heavy to be lusting after a new bike that is 10 or 11 speed? I assume that the slimmer chains are weaker. Is this correct?

Thanks

HillRider

What was the chain that broke and had you joined it using one of the standard pins, not the specific Shimano joining pin or a suitable master link?

Sasquatch16

Chain was original that came with 2006 Trek Pilot 1.0. I bought bike used last year. Original owner only did a couple charity rides on it and I have done about 1000 miles since I bought bike last year. Cassette only has about 400 miles on it. It was changed to a 12-32 to make hill climbing easier. At the time LBS indicated that chain was ok. He lengthened chain but I can see that this is not where it broke. Looks like it broke right at a standard link.

FBinNY 

Chains are all rated at loads much higher than you could ever put into them, and do not break because of weight.

I suspect you have classic chain breakage where one plate came off the pin, then the opposite plate bent as the pin slid out of the inner link. If so, this happens in two steps. First the plate is pushed outward until it's only hanging onto the pin by the edge. You can ride this way for quite a while, but the strength is compromised and the next time the chain is loaded it'll fail.

Modern chains, all have peened pins where the end of the pin is flared over the plate, or into a small countersink in the plate, to keep the pins moving out when pressed, but hard shifting under load can overcome this. Also, some people splice the chain by pushing a pin out and back, which sheers the flared off leaving a pin that the plate can slide off.

Given your weight, I suspect that the problem is shifting under load, and if you examine the rest of the chain carefully, you'll find a few other pins that are slightly dislodged.

The key to preventing chain breakage, isn't to look for stronger chains (there are none) but to avoid shifting under load. Anticipate your gear needs as you begin to climb, and shift while you still have high rpm at low load. Once you delay, the added chain tension makes shifting problematic. You can also check you chains once in a while by cutting a square notch just wide enough for the chain to pass, out of the side of an expired credit card. Run the chain through it, and any plates pushed out will snag.

The other type of breakage where a plate actually cracks is very rare, but does happen, though almost always only thinner 10 and 11s chains.

Yes, thinner chains are less strong, but only slightly so and still pass ISO standards for chain strength. They do wear faster, but under normal conditions are not any more prone to breakage.

Zef

Sht happens. Chains wear and occasionally break. We shift gears by applying mechanical stress to the chain and with the exception of certain gear combinations the chain is never running perfectly straight. While chain breakage is not a normal issue to be concerned about it is not unknown to happen. As explained in posts above, shifting habits or even isolated shifting incidents can impact the chain and cause it to be compromised...due to the stress/loads the chain receives in normal use that compromise can become failure.

The derailleur hanger can most likely be bent back...there is a tool to check how out of alignment it is and is also used to leverage it back. I would have a competent mechanic do this operation as repeated bending can cause the hanger to crack and fail and since you have not mentioned year/make/model I have no idea if your hanger is replaceable or integral to the dropout.

Have your chain replaced. Your cobbled together chain is bound to break again at the most inopportune time.

-j

FBinNY 

Chains ONLY break at opportune times, specifically when heavily loaded, as when climbing and sprinting. They ALWAYS break in the upper loop, allowing the free end to whip forward, sometimes slapping your calf or ripping off the FD. The effect of a chain breaking is similar to what happens to Charlie Brown when Lucy yanks away the football. Like a broken crank or pedal, it's rarely fun, but doesn't usually lead to serious injury (though it can).

IMO chain breakage isn't a random thing. Many strong or heavy riders never break a chain in an entire riding career spanning hundreds of thousands of miles. Others, not as strong or heavy, break chains mire than once, often while fairly new to the sport. The common denominators tend to be inexperience and poor shifting technique.

In short, chain breakage is almost entirely preventable but it's up to the rider.

Sasquatch16

Thanks for your informative response. This is the type of failure that I had. Had to press out a couple pins and reuse one so chain is getting replaced. Are the Sram chains with the powerlink acceptable. I was thinking of replacing with a link that can be removed and also carrying one as a spare in case this happens again

seashmore

Thanks for the info! I haven't broken a chain yet, and now I know what I can do to keep it that way.

sauerwald

+1 on the Wipperman chains, they wear like they were made of steel!

I have broken a chain once in my riding career - I am not overly heavy, or strong, and as others have noted, it always comes at the most inopportune time. In my case I was commuting to work in Maine, the temperature was in single digits (F), and I was running late for an early morning meeting. I think that a contributing factor to the break was ice buildup on the drivetrain.

RubeRad

Wow, that's purty! Is that seriously how wipperman chains are packaged, or did somebody mock up a necklace & earrings case for a joke picture?

RubeRad

I used to be of the impression that 8sp and below were strong chains, and 9sp and above were weak, but I learned from around here that's not really the case. I've been convinced to upgrade to 9sp, and haven't had any issues in a few months, but since I've never broken a chain before anyways, maybe I'm just a gifted shifter. Personally, I'd stay away from 10sp and 11sp, but only partly because of slightly thinner/weaker chains; mostly because all the parts are so much more expensive than 9sp! And if I recall correctly, the rear wheel needs even more dish to accomodate the extra cog or two, physics and economics dictate that the wheels are either weaker (not good for clydes like us) or more expensive.

And as for SRAM powerlinks (or any, I think all brands offer their own versions), don't even worry. There was a thread recently where we were discussing (a) is a removable link weaker, or (b) if not, why not just make the whole chain out of removable links? The consensus seemed to be, they are not weaker, they are made to be stronger, and thus perhaps heavier, which is one reason not to make the whole chain from them, also it probably costs more to manufacture removable links than regular, so the chain would get very expensive.

shelbyfv

Interesting info from FB about checking the side plates. I'm going to cut up a credit card!

Drew Eckhardt 

Some contemporary chains aren't modern.

Campagnolo 8 and 9 speed chains don't have peened pins - they didn't do that (at least not substantially) until the 10 cog era. I don't shift under load, had a 145 pound racing weight in the 8 speed era, and still broke one of the C8 chains. Broke my last C9 chain too with no shifting under load at 185 pounds.

I've used less expensive LBS replacements built that way too.

When upgrading to ten cogs with a peened chain I noticed that it took a lot more force on my chain tool when shortening it to length than one of the old C9 chains. Presumably comparisons between a C9 chain and decent Shimano chain (they switched first) would have been similar.

A master (half) link like the KMC Missing Link should also provide a more durable connection than a connecting pin which won't be peened.

Wilfred Laurier

highlighted phrase is incorrect
9 and 10 speed hubs have exactly the same spacing as 8 speed
7 speed has slightly less dish than 8 speed
and there is a difference in strength
but a properly tensioned 8/9/10 sp wheel
is more than strong enough for very heavy riders

RubeRad

OK, that's good to know. So then does 11sp need more dish?

Drew Eckhardt 

Shimano 8-10 speed freehubs are all the same width and dictate the same dish with all else equal (as FBinNY notes, it's flange position which matters and that may not follow freehub width) although the 10 speed big cog hangs off the end of the freehub. The 11 speed freehub is 1.8mm wider.

Campagnolo added about 1mm moving from 8 to 9 cogs and stayed there with 10 and 11 although each addition moves the big cog farther off the end of the freehub. I had to add an extra washer to the drive side of my 1996 eight cog hubs and make a corresponding dish adjustment when I converted them so the chain didn't rub on my drop-out when using the small cog.

Obviously the move from 7 to 8 cogs implied a dish change for everyone due to the 5mm width increase and move from 126 to 130mm rear axle.

FBinNY 

How dod we segue to talking about dish on a chain breakage thread?

Be that as itmay, unless you're concerned with predicting wheel strength based on differences in R/L spoke tension, no wheel requires more or less dish than any other, including fronts.

With very few exceptions to match asymmetrical frames ALL wheels are dished to center. Varying brands have minor differences in freehub width for 8, 9, 10, and 11s, but that doesn't change that you're still dishing to center.

In any case, it isn't freehub width, but flange position that counts. (one follows the other somewhat, but not exactly) Go to a spoke length calculator's spec. page, or use your own ruler and look at the CTF distance for the right flange. The difference between that and half the over locknut width is the freehub allowance.