Commuting - Suprised at what a bike shop told me.

I bought a bike from GI Joes and the bike section. There are several mechanics and I happened to run into one of the ones who was not as smart. I tried to get a new chain and he told me not to get a chain unless its rusted. Are you kidding me if my chain doesn't get into gear easily and its lubricated isn't that time for a new chain? Its been 6 months and about 2000 miles. Should I just have a specialty bike shop install it in front of me so I know how?

This is totally insane. Run, don't walk to another shop.

BTW, you should get more than 2000 miles out of a chain unless you've really abused it. If the shifting is bad, I suspect a minor adjustment to your rear derailleur or cable tension may fix the problem in less than a minute.

A reputable bike shop can check the stretch on the chain and tell you if it needs to be replaced.

I may have "abused it" I use to ride in hard gears to go as fast as possible during my commute. Mashing is what I usually hear it called. I don't know how to adjust the derailer, what adjustment are you talking about?

Checking for chain stretch is pretty easy. The links should be exactly 1 inch apart. This means that if you put a ruler on the left pin of one link, the left pin of the next link should be at 1 inch. If it's not, the chain is stretched. Check http://www.sheldonbrown.com (http://www.sheldonbrown.com/) for the suggested tolerances. For myself, as soon as I feel it slipping when I'm pushing hard from a stop or up a hill, I change it.

Changing the chain is something you can easily do yourself. Sheldon's site has the details, but it basically takes a tool to break the old chain. The new one will probably have a master link, so you just thread the thing through and connect it up.

When you're changing the chain, you should also check the condition of your rear cassette and front chain rings. If the teeth are looking worn down, this is the time to replace them. Again, the process is fairly simple, but does require some special tools. For about $50 in tools, though, you can pretty much take care of all this kind of stuff yourself and save much more than that over time.

I thought it only took 1 tool which is to break the chain? The same guy said someone in the shop should do it because it should be done a prescise way. How many miles do cogs usually last? I have asked several different forums how and when you should replace cogs. Do you buy new cogs online or at a bike shop and how do you know what kind of cogs to get?

Time to find another bike shop - the mechanic sounds more greedy than stupid, i.e., he's just trying to get you to pay for service i.m.h.o.

try and find out if there's a Barnett or UBI trained mechanic anywhere near you. No garauntees they'll be the best but it might be a good starting point.

http://www.bbinstitute.com/ - barnett

http://www.bikeschool.com/ - UBI

Edit: a good shop will encourage you to start doing your own work so they can sell you parts and tools for years to come - a bad shop will just try and get you bring the bike in for service and discourage DIY.

Learn how to replace a chain yourself, for one, it's an invaluable skill and it's not difficult at all. Buy a chain tool, they spin typically to push the pins out of the chain to disconnect it (don't push it all the way) as well as to push them back in and link the chain. They often come as part of bike-specific multitools.

Also, to quote Jobst Brandt, and just to make sure folks are aware of it:

"Riders often speak of "chain stretch" a technically misleading and incorrect term. Chains do not stretch, in the dictionary sense, by elongating the metal by tension. Chains lengthen because their hinge pins and sleeves wear. Chain wear is caused almost exclusively by road grit that enters the chain when it is oiled. Grit adheres to the outside of chains in the ugly black stuff that can get on ones leg, but external grime has little functional effect, being on the outside where it does the chain no harm."

So your chain isn't stretching, it's wearing, and proper oil and treatment will slow that down immensely.

Yea I found that out the hard way. I didn't get lubricant for my chain until after I had ridden it in the rain several times and also several hundred miles. I now know how important maintance is.

A ruler and a chain tool are pretty cheap tools...

12 pairs of links on a new chain will measure 12 inches from the centers of the pins... measuring 1 link is doable but it's easier to tell over a foot of chain.

This is the method we use at the shop as I am not sold on the idea of using a chain gauge...when a chain reaches 12 1/16 it's time to look at replacing it as further stretching will accelerate the wear on the drive-train.

Single speed chains as found on fixed gears, ss bikes, and 3 speeds tend to last longer as they do not get flexed laterally as does a multi speed chain.

The last chain on my fixed gear road bike (noting expensive) lasted just over 4000 km (2400 miles) of very hard riding.

A ruler and a chain tool are pretty cheap tools...

12 pairs of links on a new chain will measure 12 inches from the centers of the pins... measuring 1 link is doable but it's easier to tell over a foot of chain.

This is the method we use at the shop as I am not sold on the idea of using a chain gauge...when a chain reaches 12 1/16 it's time to look at replacing it as further stretching will accelerate the wear on the drive-train.

Single speed chains as found on fixed gears, ss bikes, and 3 speeds tend to last longer as they do not get flexed laterally as does a multi speed chain.

The last chain on my fixed gear road bike (noting expensive) lasted just over 4000 km (2400 miles) of very hard riding.

Alternatively, just pull the chain away from the front of a chain ring - if you can expose all or most of a tooth then it's time for a new chain. It's not perfect but it should prevent full drive train replacements because the chain was used for too long.

I thought it only took 1 tool which is to break the chain? The same guy said someone in the shop should do it because it should be done a prescise way. How many miles do cogs usually last? I have asked several different forums how and when you should replace cogs.The one tool you need is the chain tool to break your old chain. Many new chains have a "master link" which is just a link you can close without any tools, making installation easier. Some manufacturers' master links can also be re-opened without tools, SRAM is one such manufacturer. Master links make life easier, but you will need the chain tool no matter which chain you choose (because you will have to shorten the new chain to correct length).

There's no fixed rule as to how long cogs or chains last. Too many variables. I rode my previous chain into ground and got maybe 12 000 kms out of it. I cleaned and lubed the chain whenever I heard any squeaking. So, by the time it needed changing, the rest of the transmission line (cogs, chainrings, pulleys) was shot and had to be replaced too.

If you have the time and inclination, clean and lube chain regularly and measure chain wear as described. Chains are cheap and easy to replace, whereas changing cogs and chainrings etc takes more time, more money and special tools.

There are tools for measuring cog wear, but Barnett's manual for example suggests that simply changing chain and pedalling hard on every cog is adequate. If the new chain jumps or skips, cogs need to be replaced too.

--J

I'll take the contrarian view and say the mechanic is basically right. You probably don't need a new chain. The primary symptom of a worn chain is jumping cogs when you pedal hard. If shifting is rough just tune your derailleur. If somebody at a bike shop suggests you don't really need to spend money right now he's more than likely telling you the truth.

I may have "abused it" I use to ride in hard gears to go as fast as possible during my commute. Mashing is what I usually hear it called. I don't know how to adjust the derailer, what adjustment are you talking about?
After seeing this discussion, I'm thinking your chain might be screwed up after all. Mashing will shorten the life of a chain but that's not really abuse. Riding without lube will destroy it very quickly. I recommend using the method measuring 12 links with a ruler described by another poster.

Since this new territory for you, I don't think it is a bad idea to go to a shop. They will solve your problem very quickly and you will learn a bit more about your bike. The problem with fooling around with the cable tension or any other minor adjustment when you're not quite sure what you're doing is that it's easy to make things worse.

Having said that, I still think that cable tension could be causing your shifting problems. There is a small adjuster where the cable enters the derailleur that you can tighten or loosen with your fingers. You may find that tightening or loosening that little barrel adjuster makes things work better. If you do this, pay attention to exactly how many turns you make and in which direction so if you don't fix it, you can return it to how it was.

As far as your question about cogs (your cassette), their longevity depends on maintenance. If you don't maintain your chain or ride with a worn one, they will last MUCH shorter. The giveaway symptom for the cassette being worn is when you put on a new chain and it skips horribly (especially under load). The cassette to get depends on what kind of rider you are, what kind of bike you have, your budget, and how you ride. This is a good bike shop question.

I may have "abused it" I use to ride in hard gears to go as fast as possible during my commute. Mashing is what I usually hear it called. I don't know how to adjust the derailer, what adjustment are you talking about?

This is off topic, but to prevent you from doing to your knees what you may have done to the chain....you probably don't want to do that. Just like you wouldn't try to lug a car at 20mph in 5th gear, it's not good for you either when biking. Riding at relatively low speeds in higher gears probably slows you down, actually.

Best thing to do is to find a cadence (pedaling speed) that's comfortable to you, and use whatever gear you need to maintain that cadence given the terrain. Opinions vary widely, but most people seem to do something between 60 and 100 RPM, with newer riders usually on the lower end. So for the most part, if your pedals make a full revolution once a second or so, you're probably good. My guess is that if you're trying to stay in higher gear ratios all the time, you could be well below that.

Sorry for the unsolicited advice, but I used to do the same thing and quit when my joints started hurting. ;)

I bought a bike from GI Joes and the bike section. There are several mechanics and I happened to run into one of the ones who was not as smart. I tried to get a new chain and he told me not to get a chain unless its rusted. Are you kidding me if my chain doesn't get into gear easily and its lubricated isn't that time for a new chain? Its been 6 months and about 2000 miles. Should I just have a specialty bike shop install it in front of me so I know how?

If it sounds dumb, and is presented without justification... it's probably dumb and unjustified :)

The right thing for the shop to do here would be to measure the chain stretch. If it's skipping off the gears, it's almost certainly time for a new chain (and possibly a new cassette if it got worn down too much by the old chain). For the details on chain and sprocket wear and replacement, Sheldon Brown's the man: http://sheldonbrown.com/chains.html#stretch

Ok... maybe this is a good place to discuss this problem. I'm going to go get my copy of Barnett's Manual and Zinn. We've already got a quote from Jobst Brandt who says that chain stretch is a misnomer.

And Sheldon says that it is stretching.

I really want to get this down because I'm in the "it doesn't stretch it wears" camp. I have a feeling that "stretch" is a hold-over from the days of soft steel chains.

though If we can't hash this out here we might create a new thread.

I'll take the contrarian view and say the mechanic is basically right. You probably don't need a new chain. The primary symptom of a worn chain is jumping cogs when you pedal hard. If shifting is rough just tune your derailleur.

If you've gotten to the point where your chain is jumping cogs, you've waited to long.

Was the guy "pulling your chain?" Sounds like it to me.

Ok... so Zinn rides the fence... I have, in front of me, the 2nd Edition Zinn Road Bike Maintenance Manual. He calls it both "chain wear" and "Chain elongation". And suggests using EITHER an accurate ruler (but doesn't define what that is) OR a shop chain wear checker such as a Rohloff or Park model.

Barnett's is firmly in the "doesn't actually stretch" camp. From the 5th edition: "The reason that chains become longer is that wear occurs between the rollers and the bushing or rivet inside the roller."

anyone else?

Ok... maybe this is a good place to discuss this problem. I'm going to go get my copy of Barnett's Manual and Zinn. We've already got a quote from Jobst Brandt who says that chain stretch is a misnomer.

And Sheldon says that it is stretching.

I really want to get this down because I'm in the "it doesn't stretch it wears" camp. I have a feeling that "stretch" is a hold-over from the days of soft steel chains.

though If we can't hash this out here we might create a new thread.

Chain stretch is a misnomer in that chains don't actually undergo any process that physically and permanently elongates any individual component. Not modern chains, not old chains, not any steel chain... none of them actually stretch.

The Young's modulus (http://wikipedia.org/wiki/Young's_modulus) for steel is about 200 GPa, meaning that you'd have to apply 2000 N of force (the weight of a 200 kg/440 lb man) in order to stretch a chain by 1%, if it had an average cross-section of 1 mm². Which is way too conservative. The real figure is probably 5×-10× higher, so let's say it takes 2000 N to stretch the chain 0.2%. Thus, actual "stretching" of the chain under stress is negligible. Furthermore, this is within the elastic limit of steel, so the material would be restored to its previous length after the force was released.

In plain English, a 440 lb man can mash his entire weight down on the pedals (with a 1:1 gear ratio), and the chain still won't be permanently deformed :)

What actually happens is that the pins (plain bearings if you like) get worn down until they are slightly loose in places, which allows the complete link assembly to extend itself slightly under tension, due to the extra slack. Looks like Severian said it more precisely above!

IIRC, and I just read this this week, Sheldon ALSO says that "stretch" is a misnomer and that it is wear, not stretch, but uses the term "stretch" anyways because that's what is commonly uses. So, no conflict there.

Regardless of what makes it longer, it gets longer! That's a fact! Wanna test just ride a chain for a year (you'll destroy your cogs, but hey, this is an experiment, right?) and lay it next to a new chain...old one is longer.

I could care less if the metal itself is stretching or if it's a breakdown in the sleeves or whatever ...I do know what it does to cogs to ride on an elongated chain, though.

kmac-cogs CAN last a lifetime. Probably won't, but if you replace the chain dilligently and keep it clean and lubed you might be able to make the cogs last a really long time. The biggest indication of wear is the grooving you'll get below the "cups" on the cogs that are asymmetrical.

As for what kind to get you need to determine if you have a freehub or if you have a freewheel! If a freehub then is it Shimano type or Campy type (or are they the same now)?

Test for elongation in your chain and if it's a little bit long get a new chain. It's no big deal. Then keep it lubed. Before you replace the cogs try fiddling with the barrel adjusters. Go on Park tools websites and you can check on how to use the high and low adjustment screws, too. A quick minute messing with those will tell you if it's something more serious or not.

I only get about 1800 miles out of a chain. That's because my commute includes 4 miles each way of gravel/sand/clay roads. If it's wet, I can set out with a brand-new chain and it'll be coated with a fine abrasive sand before I get to work.

That said, I did let a chain go too long, about 2400 miles, and when I replaced it, I got bad skipping. So I put the old chain back on and I'm still running with it. I figured the cogs are wrecked anyway. I now have about 4500 miles on that chain, everything still runs pretty well but the cogs are quite visibly worn now and I have started being able to hear each link as it leaves the cog; that means they're catching (the cog teeth are getting hooked).

I have a new freewheel ready to go, I'll probably put it on this weekend.

Maybe I'll dig out a good ruler next time I'm at work w/ my winter beater. That thing I KNOW needs a new chain. 12 links to a foot eh?

That said, I did let a chain go too long, about 2400 miles, and when I replaced it, I got bad skipping. So I put the old chain back on and I'm still running with it. I figured the cogs are wrecked anyway. I now have about 4500 miles on that chain, everything still runs pretty well but the cogs are quite visibly worn now and I have started being able to hear each link as it leaves the cog; that means they're catching (the cog teeth are getting hooked).
While this method works, be aware that you'll be wearing your rings down prematurely too. If you let things get too messed up, you'll wind up replacing everything at once.

How about posting a couple pics of your drivetrain? It will let folks see how your chain sits, and close-ups of your cassette/freewheel and rings will show the relative wear. Maybe you can get some helpful opinions regarding what needs to be replaced (likely, too many opinions!).

BTW- don't buy the cheapest chaintool for $5. Buy at least a mid-priced one that comes with extra pins. The chain tool on my multitool is actually way stronger than one I bought at Walmart (BENT the contraption in half on my first use!).

BTW- the parktools website also has good info: http://www.parktool.com/repair/byregion.asp?catid=5&imageField2.x=24&imageField2.y=5

Your GI Joes may be different from mine, but I would not expect the "mechanics" there to know any more about bikes than your average Wallmart Meat department guy might know about cooking fine steaks.

The employees at my Joes seem like average retail employees who may just as well be working at Macy's.

Sadly, this is sometimes the case at even REI where the outdoor enthusiast employees may or may not be especially knowledgeable about bikes. At least in the case of REI, I find that I can usually be directed to someone who is knowledgeable. I once had an REI employee swear up and down to me that a Mr Tuffy tire liner was the "rim tape" I was looking for to go between my rim and my tube. :( She did not know what she was talking about. She knew she didn't and I knew she didn't. But she did not know that I knew she didn't. She made no attempt to find someone who could answer my questions.

That being said, most of my experiences at REI have been great.

I just measured the chain on my 'new' folding bike, since it's now got about 2000 miles on it (got it in May). Much to my surprise, 12 pairs of links measures 12 1/8"! Time to replace?

I bought a bike from GI Joes and the bike section. There are several mechanics and I happened to run into one of the ones who was not as smart.

Go find a smarter mechanic. :)

Actually, a chain wear-checker is pretty cheap. $10 at REI. (http://www.rei.com/product/710555) Then you can decide for yourself whether it's the chain or a derailleur adjustment that's needed.

While this method works, be aware that you'll be wearing your rings down prematurely too. If you let things get too messed up, you'll wind up replacing everything at once.

I'll flip the rings around when I change the chain. Bingo, whole new set of tooth surfaces. I may try flipping the cogs on the freewheel around too, but at $12 per freewheel it's hardly worth any time.

I just measured the chain on my 'new' folding bike, since it's now got about 2000 miles on it (got it in May). Much to my surprise, 12 pairs of links measures 12 1/8"! Time to replace?
1/8" is a lot. Chain is definitely toast. If you have problems with skipping after you replace it, you'll need a new cassette as well.

I may have "abused it" I use to ride in hard gears to go as fast as possible during my commute. Mashing is what I usually hear it called. I don't know how to adjust the derailer, what adjustment are you talking about?

I used to mash like a madman and didn't go through chains. Don't really have the mashing option anymore since I'm riding a three speed. It sounds to me like deraileur adjustment is the way to go.

This is totally insane. Run, don't walk to another shop.

BTW, you should get more than 2000 miles out of a chain unless you've really abused it. If the shifting is bad, I suspect a minor adjustment to your rear derailleur or cable tension may fix the problem in less than a minute.

A friend of mine bought a brand new bike and the chain had a few links that were too tight and we could never get them to loosen up. New chain solved the problem.

I was going to have my RDER cable replaced at "Joes" (down here in the Valley) about a 1-1/2 years ago.
Their "mechanic" told me the cable would cost $20-25 because they are specific to that model bike + about $10-15 labor.
Total Bull!
I took it to the LBS and it cost me $12.
I would have done it myself, but my old Shimano "deer head" Rder had the clamp nut located so that I couldn't fit any of my wrenched to it. The LBS fought it for 20 minutes before they got it off!"Joes" probably would have screwed it up besides! To me, the $12 was cheap, considering it was done right!
I now wouldn't even think about trusting "Joes" for ANY bike advice.

A friend of mine bought a brand new bike and the chain had a few links that were too tight and we could never get them to loosen up. New chain solved the problem.

There's a trick for that... flex the chain back and forth sideways (against the natural direction of motion) with your thumbs. After a few cycles and maybe a drop of lube, it'll loosen up.

I just measured the chain on my 'new' folding bike, since it's now got about 2000 miles on it (got it in May). Much to my surprise, 12 pairs of links measures 12 1/8"! Time to replace?

Yes, it is time!

I get about 2,500 to 3,000 miles out of a chain.

There's a trick for that... flex the chain back and forth sideways (against the natural direction of motion) with your thumbs. After a few cycles and maybe a drop of lube, it'll loosen up.

We tried that. Didn't work.

We tried that. Didn't work.

Ah, too bad. The only time I've seen a chain where it didn't work is where the plates had been forcibly bent by improper use of a chain tool.

Ah, too bad. The only time I've seen a chain where it didn't work is where the plates had been forcibly bent by improper use of a chain tool.

It didn't look like it was noticeably bent. I just suggested replacing the chain after we had been monkeying around with it on a few rides so he did. One ride I remember his chain was skipping so bad that I had to ride back to my car to pick him up. That's the point where he just said screw it and bought a new chain.

I helped him install the new chain before one of our weekend rides and he never had any trouble with it after that.

Ok... maybe this is a good place to discuss this problem. I'm going to go get my copy of Barnett's Manual and Zinn. We've already got a quote from Jobst Brandt who says that chain stretch is a misnomer.

And Sheldon says that it is stretching.
I do????? I don't think so!

"Chain stretch" is sometimes used as a sort of shorthand way to describe the elongation of a worn chain, but I don't think anybody with a clue about metallurgy thinks they actually stretch plastically.

It's a bit of traditional bike shorthand like the use of the term "alloy" to refer to aluminum.


I really want to get this down because I'm in the "it doesn't stretch it wears" camp. I have a feeling that "stretch" is a hold-over from the days of soft steel chains."Soft steel chains?" When were the "days of soft steel chains????" I never heard of such a thing!

Sheldon "Soft Steel?" Brown

"Soft steel chains?" When were the "days of soft steel chains????" I never heard of such a thing!

Sheldon "Soft Steel?" Brown

Indeed. As I explained above (http://bikeforums.net/showpost.php?p=5794336&postcount=21), no steel chain will stretch. There is no workable form of iron/steel chain that a reasonable human being can elastically deform... even an identically-dimensioned aluminum chain (1/3 the Young's Modulus of steel) would probably be impossible.

"Soft steel chains?" When were the "days of soft steel chains????" I never heard of such a thing!

I believe that term came about during the transition from chains made from harder materials such as flint and granite.....

I believe that term came about during the transition from chains made from harder materials such as flint and granite.....

I prefer the granite chains with the hollow links and pins, they're lighter.

I do????? I don't think so!

"Chain stretch" is sometimes used as a sort of shorthand way to describe the elongation of a worn chain, but I don't think anybody with a clue about metallurgy thinks they actually stretch plastically.

It's a bit of traditional bike shorthand like the use of the term "alloy" to refer to aluminum.

"Soft steel chains?" When were the "days of soft steel chains????" I never heard of such a thing!

Sheldon "Soft Steel?" Brown



I sit very strongly corrected!

oops!


(tongue firmly planted in cheek) Really what this is is the recognition that while yes, things were harder "back in the day", the technology we have today is what changed! Life is still hard and we still have to bike uphill both ways in the snow. But now we've got Tungsten Carbide Diamond-tipped studded tires, heated chammy and carbon-fiber valve-stem covers signed in gold by Lance Armstrong.

So there!

Indeed. As I explained above (http://bikeforums.net/showpost.php?p=5794336&postcount=21), no steel chain will stretch. There is no workable form of iron/steel chain that a reasonable human being can elastically deform... even an identically-dimensioned aluminum chain (1/3 the Young's Modulus of steel) would probably be impossible.Don't be so sure...30something years ago I came upon a supply of aluminum chain at Eli Heffron's (http://www.eli.com/index.cfm?t=history). Not sure what it was made for, maybe some sort of conveyor belt in a corrosive environment.

It was the same dimensions as 1/2" x 1/8" bike chain, except that every few links the rivets stuck out about an inch past the plates on one side. I was trying to make a super-light 3 speed out of my old Peugeot PX-10 frame...Weinmann wood-filled rims/Clement Criterium Seta tubulars, Sturmey-Archer AW hub that I had disassembled and attacked with a grinding wheel to make it lighter (including what might be the world's only double-butted indicator spindle!)

Anyway, when I got it all together, I put the aluminum chain on it (after cutting off the protruding rivets. I rode it to work, about 3 miles, and by the end of the commute the chain was skipping very badly. I moved the axle back in the dropouts to take up the slack and rode home, but when I got home the chain was elongated even more so as to render it unusable. I believe this chain did actually stretch.

Sheldon "Bike Hacker" Brown

Don't be so sure...30something years ago I came upon a supply of aluminum chain at Eli Heffron's (http://www.eli.com/index.cfm?t=history). Not sure what it was made for, maybe some sort of conveyor belt in a corrosive environment.

...

Anyway, when I got it all together, I put the aluminum chain on it (after cutting off the protruding rivets. I rode it to work, about 3 miles, and by the end of the commute the chain was skipping very badly. I moved the axle back in the dropouts to take up the slack and rode home, but when I got home the chain was elongated even more so as to render it unusable. I believe this chain did actually stretch.

Sheldon "Bike Hacker" Brown

Oh dear... I *knew* I'd regret venturing the guess that even an aluminum chain wouldn't stretch, with Sheldon Brown lurking around the corner :p

The Young's Modulus of aluminum is 1/3 that of steel, which moves elastic deformation of an aluminum chain out of the negligible regime (<0.1% for a normal-strength human), into the regime where it's significant, 0.2%-0.3%.

And what I didn't think of before is that the yield limit of aluminum is fairly low. According to wikipedia it's probably only about 0.2% offset strain... meaning that if the tension elongates the chain by 0.2%, it will be permanently deformed. It's likely you ran into this limit.

With a Young's Modulus of about 69 GPa for aluminum, based on my above estimate, you would need to put 690 N of tension on the chain to reach 0.2% offset strain. That's about the body weight of a 160 lb. human. So, very easy to do (and even easier with a small chainring :)).

Sheldon Brown, I salute you. You seem to have experimentally tested the materials properties of aluminum, in bike chain form. :beer:

EDIT: Sheldon, do you know the alloys typically used in steel bike chains? Its plastic yield limit varies a lot depending on the alloy, http://en.wikipedia.org/wiki/Tensile_strength. Typical structural building steel apparently has a plastic limit of only about 0.1% elongation... which is too close for comfort with a bike chain.