seely

I put a new KMC chain on my fixie and got everything all tightened up, chain was set extremely tight, so I took it out for a spin and it was working great. Skidding was no prob, chain tension felt great. Well, I'm coming down the biggest hill in downtown Grand Rapids and skipping here and there to check my speed when all the sudden, *ping!* and there goes my chain... mind you this is maybe 1/4 of the way down, and there are 5 traffic lights before you get to the bottom, not to mention they are all red and there is cross traffic. I'm dragging a shoe, its not doing a whole lot. I'm starting to think about laying the bike down and letting my bag take the impact, but I'm going 25+ so the thought is a bit scary and definately last resort. Finally, just as I am approaching the first bigger intersection the light changes, cross traffic clears and I can make a really hard right turn. Thankfully I was able to stop pretty quickly since there was a slight uphill on this street, but my heart was still racing. Closer inspection revealed that the chain had stretched essentially an entire half link on one hill's worth of riding. Chainline was ok, but I guess the backpressure just popped that chain right off. Anyways, I said screw it and today called my boss and had him order me one of those chains thats made entirely of half links. Chain stretch kiss my ass!

rvabiker

How does that have anything to do with chain strecth? Sounds like you had it on there too tight and the thing broke...

fixedpip

I think your rear wheel must have slipped. Chains don't 'stretch', they wear. To quote Mr Brown:

"This is not actually how chains elongate. The major cause of chain "stretch" is wearing away of the metal where the rivet rotates inside of the bushing (or the "bushing" part of the inside plate) as the chain links flex and straighten as the chain goes onto and off of the sprockets."

So moving to a half link chain would not really solve anything.

seely

No slip, rear wheel was perfectly straight as ever, and the chainline was still perfect after i stopped and put it back on, and no it didn't break. I use a 12" wrench w/ track nuts to tighten my rear wheel down. Chainrings perfectly true too. I reset the tension after limping it home with a saggy chain and then went back out, and even then I still came back and had noticeable less chain tension than when I set out.

I'd have to disagree with Mr. Brown. While I know the chain does not literaly stretch like an elastic band, I think it does enlongate over time. When I was riding BMX we had the same issue with chains, you would take them on one ride and then get nearly a halflinks worth of slop. It makes sense to me, I mean there is some room I'm sure for the pins/bushings to settle in seeing as they never experience any sort of load until they are on a bicycle, so it seems to me that a ton of load like a new chain would experience on a fixie would stretch the chain out fast.

sohi

WHAT? you bought a half link chain to help with chain stretch? I have the
shadow conspiracy chain and it stretches faster than anything else I had before.
It makes sense because the chain links are bend into the shape they have and
by pulling on the chain you "unbend" it. A regular chain link is straight so the pulling
force runs straight through them

summerinside

(and that's why i've got a brake)

rvabiker

There's no way I buy that your chain stetched enough in one ride to throw it. While I agree that chains stretch (Sheldon Brown is not the be all-end all as far as fixies are concerned) I just can't see it stretching that much.

zip22

where exactly did the chain break? and i agree with everyone else. halflink chain wont solve a non-existant stretch issue.

rvabiker

He threw it, it didn't break.

spud

yeah that seems excessive, and why didnt you have a 15mm wrench to readjust it? youre using chainlube right? have you measured it?

popluhv

Overtightening a new chain, and then skipping on it? Sorry, but you got what you asked for.

baxtefer

user error

freddiesan

I have to agree that it sounds like user error. Hey Grand Rapids! You must be neighbour with Slingshot bicycles then? Tell them my frame broke 8 years ago and that I want a replacement.

chzman

it was the travelocity roaming gnome that pulled the chain off

na975

if you had bought an Izumi V this wouldn't happen.

Re-Cycle

I didn't catch, 3/32 or 1/8 ?

points of interest:
-Steel dosn't stretch, bushings wear out. Period.
-No matter what brand the chain is, its bad to make it reealllyyy tight.
-Even the cheapest KMC chain wouldn't do that if it was tensioned properly. Remember that the condition of your botom bracket and rear hub greatly affect your chain's desire to stay on. If you have play in either you may *think* your chain is tight when really it wants to say 'Cya'.

I'm currious, if this guy wrecked bad would anyone wake up and put a front brake on? I doubt it.

popluhv

No, but then I would never ride 25mph+ down a hill into an intersection.

rvabiker

Doesn't matter does it?

screamingveg

I would and do, but I also have a brake.

spud

hhahahahaha, biggest bunch of bull in this thread since the first post.

rvabiker

Glad someone pointed that out...

operator

Well N.S. You need to get better reading skills. Chain "stretches" because it wears. He says it right on the fracking page.

LóFarkas

Guys, I thought the FGSS bunch wasn't as ******** as the rest of BF (or the world? or is that the same?)

Here's a few home truths about chain stretch.
Sheldon is right in saying that chains never "stretch" in the strict sense of the word, like an elastic band. The pins and the bushings (or the widened lips in bushingless chains) wear from friction; they develop longitudinal play, if you like. Of course, that does make the chain longer. (Which Sheldon also clearly states. He has nice illustrative photos which I'm too lazy to find now) So lets call it chain stretch and wink knowingly when we say it.

It doesn't surprise me if a brand new chain stretches pretty fast in the first days. During manufacturing, little burrs can be formed on the bushings, etc. These wear down quickly, and the chain settles at its normal length, and starts its slow wear from there. I guess even the generously applied factory grease can keep the pins and bushings slightly apart when you install the chain. As soon as you stomp the pedal, the tension forces it out, and the chain lengthens a bit.

I'm pretty unsure about what happened to the OP. It seems improbable for the chain to have stretched enough to fly off... but then, it was a downhill skip, so there was a lot of force involved. Possibly a small pothole helped in with a big jerk...possibly it was a slightly sideways "hockey skid" that made the frame flex, and effectively shorten the chainstay for a moment. I read somewhere that frame flex does screw with chain tension a lot.

Long, eh?

(Another story chalked up to my "Riding brakeless is not very clever, however zen you are. For example..." list. It's your life, you are entitled to do silly and dangerous things. I do some myself. I'll prolly never do brakeless, though. Being oh so cool is not that much of an objective to me.)

MacG

It's true. Chains may literally stretch a small amount, but the vast majority of the elongation everyone calls stretch is due to the bushings being eaten away.

seely: can you measure the chain in question for us? Just grab a measuring tape or good ruler and center the 1" mark dead-nuts on the middle of one of the rivets. With the chain held tight, look where the 13" mark falls. Is it centered on a rivet, or a bit off? How much off? If you managed to elongate a chain by even 1/16" during one ride, you either bought one hell of a ****ty chain or you did something seriously wrong.

I'm pretty sure that when you measure the chain, it will match up almost perfectly on the inch marks over a foot of length. Are you sure you didn't bend your stays somehow or mess up your BB?

Lunigma

Only a fool would disagree with Sheldon (bike-wise that is). you didn't mention if you put chain lube on the chain, you didn't mention if you put a new cog on either.

a new chain (even a crappy one like KMC) will wear faster with an old cog, no lube and a super tight chain. you did sooo many things wrong. what size chain ring and cogs are you running? cogs that are smaller than 16T are known for jumping the chain off easier. a short wheel base will help make it jump aswell. even if your chain did get really really stretch out that wouldn't be enough of a cause for it to jump, it needs another force.

get a brake if you don't know what your doing.