jambon

Hi there ,

This Question is going to seem seriously OCD ,but i am curious about this from a physics and materials perspective as much as from a Bike maintenance one .If a bike is in the shed and isn't going to be used for months on end , for example , my summer touring bike ,should the chain be removed so that it isn't stretched under the tension of the rear derailleur ?And for that matter should both the derailleurs be put in a position where there is no cable or spring tension so that they dont lose any tautness over the winter ?

KBentley57

From a physics standpoint, the chain is under so little stress from the rear derailleur that it essentially doesn't feel anything. Think about the tension they are designed to withstand, and the small amount provided by the derailleur. It's only real purpose to to take up slack. The same goes for the springs in the front and rear derailleurs. They are strong springs no doubt, but they are only stretched/compressed a small amount, and never enough go go beyond plastic deformation.

However, if you're storing it in a humid region with no movement for long periods of time, then it probably would be a good idea to remove the chain, soak in oil/wd40 and keep in a jar somewhere, just to keep it from rusting. Same goes with the derailleurs, if you have to remove the chain, shift them to their least tension state afterwards. If you give the chain a quick wipe down with lube every month or so while it's not being ridden, I don't think you'd be able to tell the difference though.

Retro Grouch 

If you wanted to wear out a piece of metal you'd rub it against something. Since there's no rubbing motion going on with your bike in storage, your chain isn't going to wear.

GravelMN

If you are planning to store your bike for 50 years or more, then you might want to worry about it. Shift the derailleurs to the lowest tension position then just properly lubricate everything, maybe apply a storage lube like LPS3 to the chain, and call it good until spring.

KenCarlson

Chains elongate, but not by stretching. Chains get longer by the pins wearing due to friction from riding, so chain "stretch" is a misnomer. If your bike is going to sit for a few months, no wear to the chain will occur and it will be exactly the same length at the end of storage as it was when it entered storage.

On the other hand, it can rust while just sitting there, so it's helpful to clean and lube the chain before storing it for the winter.

-Ken

rydabent

For the most part my bikes hang in the winter. I hate riding if I cant ride in a t-shirt and shorts. The tension on the chain will not cause it to stretch. How ever I do shift the chain to the small-small chain rings to releave tension on the spring in the RD.

jambon

Thanks for these inputs , that the chain is worn by movement and friction and not by stretching tension from deraileurs makes a lot of sense .

HillRider

Metals do not elongate from tension below their yield stress no matter how long it's applied. There is a phenomenon called "creep" but it is so small at any normal temperature that for all practical purposes it can't be measured. You could leave your chain under derailleur spring tension and the derailleur springs themselves under tension for centuries with no problems. Repetitive load cycling (cycling as in applying and relaxing the load, not bicycling) eventually fatigues springs but a static load within their design parameters has no effect.

As mentioned, rust, not tension, will damage an unused and unprotected chain.

Andrew R Stewart 

As mentioned, shift into the cog combos which the ders default to minimize their springs' stretch. Lube all the pivots, cables and chain. keep as dry as possible. Air up the tires periodically. Hang from the wheels to get off the floor/ground. Visit it and tell it you miss riding. Invest in well fitting cold weather clothing and take it out and ride. Andy.

Northwestrider

Chains don't stretch , they wear

JohnDThompson 

Chains "stretch" as a result of wear: abrasive grit erodes the pins and rollers and the added clearance over the length of the chain is measured as "stretch." But a chain that is not in use does not suffer any wear, and so will not "stretch" in storage.

cny-bikeman

Wow, just wow. You could store the bike for 100 years with no "stretch" (wear) on the chain from the tiny amount of tension. I would caution you against doing any work on your bike, as there's a possibility that you might cause some harm. In fact, just hang it in a climate controlled, nitrogen rich atmosphere away from any sunlight.

Grand Bois

As mentioned above by Hillrider, that accomplishes nothing.

AnkleWork

I love this thread! Many thanks.

Kimmo

Hmm

JerrySTL

If you want to worry about something, worry about all the springs in the shifting system when the bike is sitting around. I know people who shift down to the smallest front and rear gears to reduce tension on the derailleur springs to keep them in good shape.

Of course when you get back on the bike and forget that it's in a 39x12 combo, don't blame me if you have trouble getting started.

mconlonx

Overthinking.

Chain stretch is a result of wear via use, not actual stretching over time because of tension. In 10,000,000 years under derailleur tension, your chain wear would measure the same, assuming non-use.

Black wallnut 

Finally some entertainment outside of the 41.

FBinNY 

Even if storing for 1,000 years, there's no need to relax tension on metal parts or springs. Steel doesn't stretch or sag over time. Stretch or sag only happens when the elastic limit is passed from overload, which distorts the part. If this weren't the case, bridges and buildings would sag under their own weight.

Chains are also a special case, because when we speak of chain "stretch" we're not talking about the effect of tension. What chain stretch describes is a wear effect which increases the play at each pin and link allowing the links to move farther apart. In this way, chain stretch is analogous to how freight trains stretch as the engine and cars pull out and takesup the slack at each coupler. Each car is still the same length, but slightly farther from it's neighbor so the overall length of the train is increased -- "stretched".

Looigi

FWIW: It might be useful to appreciate the tension the chain can be subjected to while while riding. For example, if a 160 lb rider puts all his weight on a forward pedal while climbing in a 34 tooth ring, the chain tension will be ~3 times the riders weight or about 480 lb. A strong heavier rider could double that. A smaller ring and/or a longer crank will also cause it to increase.

Reynolds 

This concern probably might be traced back to the worries of some firearms owners about the weakening of springs over time if storing fully loaded magazines. This believing has been refuted countless times, but still resurfaces now and again.

AnkleWork

Exactly. Springs lose tension via cycling.

Davet

^^THIS^^is the very best explanation for chain "stretch" that I've seen! Not stretch but elongation.

Andrew R Stewart 

Tangent- So the parallelogram springs of moderate cost Shimano mountain rear ders that lost their tension over time isn't from the bike being ridden/left in the lowest rear cog? Same question about the cage springs of those Huret Alvet ders and the Dia Compe early 1980s side Pulls. Andy.

FBinNY 

Steel springs don't sag because of static loads, nor do they from repeated cycles (until we hit very large numbers) unless operating near the elastic limit. A single instance of flex beyond the elastic limit (impossible in an RD parallelogram) can "cold set" a spring - like a 350# man standing on a scale rated for 250max), but other than the effect of the set, the constant would stay the same.

Repeated flexing close to but shy of the limit can accelerate a fatigue process, and either set the spring or lower the constant, but we're talking about a very long, slow process. Eventually with repeated flexing near the limit fatigue sets in and the spring cracks.

How long this all takes and the extent of the effects depends on the spring design and material. Some steels make better springs than others, and certain alloying element in "spring steel" can greatly increase the fatigue life and/or prevent sag (except if overloaded).

IME- I haven't seen measurable changes in RD springs, but I've seen the effects of fatigue in brake caliper springs, especially those with only a single coil. These don't get weaker, they simply crack. Otherwise spring "fatigue" on bikes is probably a matter of lousy material or poor design, probably the first, especially on low end canti brakes.

Where you're most likely to see changes in springs are in machine or automotive applications where springs see repetitive or constant abuse. Compare the life of an RD spring to the valve lifter spring in an engine which is flexed 500-1,000 times per minute for years.