WhyFi

Yeah, but will this thread stretch?

tagaproject6

Stretching the thread...?

Aubergine 

jon c. 

Or will it just wear?

tagaproject6

Hah, indeed, the way you are ignoring obvious evidence and simple physics is fascinating indeed!

Reeses

79pmooney

Yes,all you say is true. Wire cables do both of those. Construction stretch is the fibers being pulled into a more compact cross-section when a large tension is applied to the cable. The cross-section becomes more compact as the fibers are stretched straighter. But bicycle chains don't behave that way at all. Elastic stretch is just that. Stretch that only exists while the metal is subject to tension. Release the tension and it reverts right back to where it was. (Like a rather strong rubber band.) Nobody measures elastic stretch although it is not difficult. You just need to apply sufficient tension to make for enough stretch to measure and do it with the chain not moving so you can actually measure it. I'm guessing it does add to permanent stretch indirectly. Under high pedaling loads (especially with a small chainring) the chain stretches more elasticly so the most heavily loaded teeth wear more. When the teeth wear, the chain "stretches" to fit - probably by bushing wear. I am also guessing this is a second order effect. In other words so small relative to the big sources of "stretch" that it really doesn't matter.

(Yes, bushing wear adds to permanent "stretch" by creating play inside the rollers. When the play is pulled out, the chain is now longer.)

And a related source of "stretch" - also common in climbing situations - poor chainlines, With a poor chainline, the bushings at the outside of the local bend in the chain (The chain now forms an "S" with bends coming off the cog and into chainring.) Those outside bushing see nearly all the load of the chain and therefore wear much faster. Faster chain "stretch".

Note, when I say "stretch" with the quotation marks, I mean elongation in the chain as a whole due to wear. Ie what you can measure with a tape measure.

Ben

smashndash

Sorry to derail this thread, but I'd like to address the topic in the OP. All my life I've been told that there's a massive difference between Walmart/low end bikes and shop bikes. I am a bit less inclined to believe that now than I was before I bought a real shop bike. Here's my (long) story:

My first bike was the good ol Walmart classic. Dual suspension. Aluminum. 21 speed. Shimano. Twist shifters. MONGOOSE mountain bike.
it was fine. Seriously. A $130 bike. I enjoyed riding it. It shifted pretty damn well. The suspension was probably for show but I could use it as a trampoline. Eventually I outgrew it and decided I wanted an expensive, luxurious bike. So I got a bikes direct hybrid. $350 my God. Of course it was a size too small. So I got a longer seatpost, stem and bars. That bike worked worse. The brakes (mechanical discs) were trash on the black diamond trails I suddenly thought I could ride. The shifting was better because of the triggers but otherwise fine. Overall, meh.

And then I got myself a $600ish fixie for $300 used. Aluminum frame. Half carbon fork. 40mm deep alloy wheels that weigh 3000g at least.
I was a LOT faster on the road (obviously) and I could put some real pressure on the pedals. This was the best bike ever! Sure the cranks (square taper) clicked and brakes were spongy but it was fast.

And then I got a $1700 road bike. This is probably my least favorite bike of all. I've had a lot of problems with this bike. Ive had a lot of problems ON this bike. I can't say it's necessarily more fun to ride than my Walmart bike. Sure, it's faster. A lot faster. And that lets me hang with other people who have fast bikes. But I can't say that a road bike that costed $200 or so wouldn't be as fun if I upgraded the tires to the ultra thin ultra sticky race tires I have now. Or even much faster...

Something deeply cynical inside me says that my next bike, which will probably cost somewhere between $5000 and $15000 (depending on how crazy I go), will be even less fun than my $1700 bike and will have even more issues. And I'm really not looking forward to it. I want someone to tell me that I'm wrong. And I want to believe it. But from where I'm standing, I can't.

growlerdinky

nitro glycerine as a ped

Racing Dan

I would believe the perceived stretch of gear cables is in reality the wire bedding/wearing into the housing or the wire guide under the BB. Except for really poor quality wires I cant imagine the tension on a bicycle gear cable being large enough to permanently stretch the cable.

Racing Dan

I believe ppl have replied to the stretch part of your post. I will just add that you likely need an other oil. Too much "bike specific" crap on the market. Get a thick oil like mono grade sae 40 engine oil, that actually manages to prevent metal to metal contact and I bet you should be able to get more than 1000.

Ghazmh

Racing Dan

Good one. I had a mechanic "diagnose" my old commuter with a 8 speed IGH. All it needed was a fresh chain and sprocket. I was told I needed to replace the whole IGH mechanism at considerable cost. Right! What a scoundrel ... :-)

indyfabz

You don't need to replace your helmet after 5 years is a myth I no longer believe.

rubiksoval

If the OP is replacing chains after 1000 miles, he's likely clueless on maintenance. I get 3500-4000 miles out of my Ultegra chains (and could probably get another thousand or so more), and I guarantee I put out substantially more power than he does at all times. Higher power output is not the issue.

TSUNAMIBAY

Okay, so I measured the individual links on both my old chain and the new one. (same brand Ultegra) Using a digital dial caliper the average link length on the old chain is .837" +/- .001"
On the new chain the link lengths averaged .832" +/- .001", which would correspond with the overall length I observed.

We used to have to replace the chains on our overhead hoists every couple of years due to lifting 10-15 ton dies. They would stretch as well, why is it a surprise that a chain would stretch as well?

TSUNAMIBAY

Curious to know how you are going to guarantee this?

rubiksoval

I weigh 10 lbs more than you.

And I'm a Cat 1.

TSUNAMIBAY

Oooooh, scary....

rubiksoval

in a thread full of

Colnago Mixte

I'm not sure why people are saying chains don't "stretch" when it's pretty obvious to me that they do. Is there some more technically correct term to use such as "elongate" or "expand"?

If we can't even get a consensus on that simple observation, then this thread probably IS a waste of time.

indyfabz

Whatever gave you that idea?

rubiksoval

"Wear out."

jasnooks

Did you measure the distance between the center of the pin holes, or just measure the oal of the plate?

Edit: While I know that chains get longer due to wear, I'm curious if it's also due to links stretching. I've never measured a link plate myself.

OBoile

Track cyclists snaps a chain in this video during the crit IIRC.