chain stretch
 

Just built up a fixed 92' trek 400. I'm just wondering how much chain stretch I can expect out of a brand new 1/2x1/8 kmc bmx chain. I have about 10mm left in the back of the dropouts. It worked out well because I was able to get good chain tension with the axle far forward in the dropouts, but since they're shorty horizontal dropouts I just need to know if I can expect the chain to stretch too far...

Thanks!

If your chain stretch more tha 1/8" its time to replace it.

if you are running brakeless you will be torquing your chain a lot more. a chain under normal circumstances will begin to stretch in six months.

not only is this untrue, but it's a use of the term torque that doesn't make a bit of sense. Riding brakeless will make the catastrophic failure of your chain from improper installation more likely though.

How is that? Tension is tension, isn't it?

He says catastrophic failure, so I guess failure without a brake vs. with one will more likely be bad for your health.

How could I have installed my chain incorrectly?

Not correctly push the pin in place, stretching it too tight, twisting a link while getting it fitted or put together, etc.

Not only is it actually true (come on, of *course* you put more rearward pressure on the cranks and chain than if you were coasting or using brakes), but you actually basically just repeated a version of the quote you were trying to poo-poo by DROPPIN KNOWLEDGE.


And that's a fine colloquial use of "torque"... You really didn't know what the poster meant?

Brakeless, more like 4 days.

maybe thats just me though.

To be really literal, your chain starts stretching as soon as you start riding; but no--a chain of any actual quality won't show noticeable stretching in that short a time.


If you're serious though, what you're feeling is more likely a symptom of the rear wheel slipping in the dropouts.

I understand axle slip and, but I can definitely feel the stretch in my chain after about 4 days.

then again, my bike is my only method of transport, and i ride pretty hard and ridiculous.

^^^^^^^lol

^ SMC chain, 4 days of me riding hard, yeah, it stretches.

^^^^^^:lol:

What, is it made of aluminum?

Maybe he does a lot of riding in 2000+ degree heat. Who are we to say that he doesn't? He did say "rediculous."

just measure it. Measure 12 pins, it should be 1 inch per pin.
By the 12th pin, if it's 1/16" over, it's stretched.
If it's 1/8" over you prob need to replace chain and cog/chainring as well.

i'm too lazy to paste the link, but read sheldon's article on chains.

A new chain goes through a break-in period but you're not going to "stretch" a chain in four days, no matter how "hard and ridiculous" you may ride.

Sheldon Brown on Chain "Stretch":

Cyclists often speak of chain "stretch", as if the side plates of an old chain were pulled out of shape by the repeated stresses of pedaling. 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. If you take apart an old, worn out chain, you can easily see the little notches worn into the sides of the rivets by the inside edges of the bushings. With bushingless chains, the inside edge of the side plate hole that rubs against the rivet has a smooth radius instead of a sharp corner. This probably contributes to the greater durability of bushingless chains.

I guess I'll just measure it when chain tension starts to become iffy. Because I'm pretty sure my axle is goin anywhere....

thanks for the info

Since one 'link' is actually two sections (one with 'outer' plates and one with 'inner' plates), don't you mean two pins/rivets per inch, or one inch per link?

No, it is not actually true.

Of *course* you put more rearward pressure on the cranks of a fixed gear than a freewheel (some > none). But, the max amount of pressure you can apply in the backwards direction is no greater than what you can apply in the forward direction. Besides, the direction of tension (not torque) doesn't matter. Action = reaction, so the forces on the chain's links & plates is the same. So, the amount of tension on a fixed gear chain is basically the same as on a single speed or geared bike chain.

Just because we all know what the OP meant by "torque" doesn't mean he/she used it correctly. You can no more torque a chain than push a rope.

Unless you are exerting the same amount of force at the crank on a lower gear.

You seem confused. ..And indignant. I'm saying that if you don't use a brake to slow down your wheels, but instead use the same chain that you used to get the wheels moving in the first place, clearly the chain is putting in more work. Not that it matters at all, but it is baffling to see how hard this is for new fixie-bros to understand.

oops. Thanks for the correction. Yes, I mean 1 inch per link :)