regomatic

The thread on compact cranks started to diverge into a discussion about chains so I though it best to start a new more specific thread on the subject.

When I started regular club riding on my Campy 10sp Chorus equipped single, I usually rode about 5,000 miles between chain / cassette changes without any problems. My first mechanic was a racer and recommended changing more often but he certainly stressed his equipment much more than I did and had a lot more riding on potential failure. I didn’t do any of the mechanicals when I first started riding, just figured I got enough miles on that set, drop it off Monday, pick it up mid-week.

I didn’t consider any major differences in chain stress and wear when we started riding tandem until we broke the timing chain on a ride a few months ago . Fortunately, we were not at the very back of the group and a couple of riders stopped and helped us with on-road repairs that I wouldn’t have known how to do. We took links off the right side and spliced them into the left side.

Once home, a phone conversation with my new tandem mechanic / consultant sent me to the bike shop with a shopping list of parts and tools to replace both chains and the cassette and instructions on how to complete the repairs myself.

As a result, I learned a few valuable lessons about chain replacement and repair;
• How to use a chain tool
• Add and remove links
• Borrow from the right side to fix the left side
• Chain replacement
• Cassette replacement
• PowerLinks
• Loosening a “stuck link”
• Using a chain wear tool


When I took off the old chain I found two other links that looked like this;


Obviously, we were lucky to make it home without additional repairs or a call for a SAG wagon. I'll be making visual inspections more often and will start using the chain wear tool regularly. I need to order a couple of PowerLinks that I can put into an emergency repair splice so I don't have to cannabalize one side to fix the other.

I am trying to become more self-reliant, step-by-step, to do more of my own maintainence and repairs. What other chain insights do the almighty internets advise?

lopsided

I don't have any words of wisdom but since we ride a tandem, I have to ask what brand of chain is that? I can't make it out from the pictures.

regomatic

I took the pics and then tossed it, it was OE on a Trek T2000, so I assumed Shimano, no telling what group. Maybe one of the experts here can recognize it by the markings.

I chalked the breakage up to maybe they don't always put the best stuff on, figuring lots of folks are going to upgrade or change out to personal preferences anyway, or more likely, I should have known better and regularly checked the condition of the chain long before it failed .

On the recommendations of the mechanic / consultant we put Sram 8 sp on the front and a Sram 9sp on the back. We had an incedent with a stiff link about 5-6 rides later, now I know how to fix that too. After that, they seem to be working fine.

So far, as long as the maintainence and repairs are relatively minor and there's someone around to offer advice, I have adequate logic and mechanical skills and motor function to make the repair. It's mostly about "what I don't know about what needs fixing" that I don't know how to fix.

TandemGeek

It's a SRAM chain: icon on the side plate is a dead give-away. Based on the two-tone color, if it was a 9 speed chain it's most likely a PC59 or, if it's 8 speed, a PC48.

lopsided

Thanks for the info. Our Burley came with a Shimano chain on the rear but it doesn't have very much wear on it yet. I have purchased a 9 speed Ultegra chain to replace it with when necessary. At one time, I wanted to go with a Wipperman until I checked their price changed my mind pretty quick. I still have much to learn about the differing mechanics of a tandem versus a half bike, but I'm fairly confident it shouldn't be too hard to manage. Good luck to you, you should be able to pick it up quickly.

JanMM

No reason to use a 9 or 10-speed chain for the synchronizer. 8-speed will be cheaper and maybe stronger. Check the adjustment of the eccentric bottom bracket occasionally so that you don't have the chain too tight at any point.
I replaced the synchro chain on our tandem last summer and found that putting the chain back on was very tricky - not easy to keep both cranksets exactly oriented to each other. Any tips?

TandemGeek

Everything you need to know about chains: https://sheldonbrown.com/chains.html

As for words of wisdom, I guess the only question I'm left with from your broken chain was how/why did it break? A side-plate break like that would seem to indicate that the chain has previously been damaged or that the timing chain had so much slack that it derailled itself near the stoker's cranks and then twisted around the crank arm or axle. If that was the case, proper timing chain tension is pretty important. You don't want it too loose or too tight.

There are several postings in the archives related to timing chains, eccentrics, and the like that you can drill-down on from the following reply... a poppourri 'o previous postings if you will.

https://www.bikeforums.net/showpost.p...5&postcount=31

Some of these may be repeats from the previous link:

Timing chain wear, replacement, and rotation:
https://www.bikeforums.net/showpost.p...30&postcount=2

Timing chain / eccentric adjustment - how to get the tension just right:
https://www.bikeforums.net/tandem-cycling/123493-timing-chain-adjustment.html#post1384113

Timing chainring alignment:
https://www.bikeforums.net/showpost.p...3&postcount=36

Setting chain tension to allow derailling by hand:
https://www.bikeforums.net/showpost.p...8&postcount=37

TandemGeek

Practice? Actually, there are a couple "tricks".

The first isn't so much a trick as it is a built-in benchmark for crank arm alignment: most seat posts are parallel so if you get the front crank lined up with the captain's seat post, you should be able to get the cranks back in sync by positioning the stoker's crank to be in line with the stoker's seat post when you put the chain around it's rings.

The second one is a trick: with your cranks properly aligned, clean off a spot on the chain ring and chain plates that sit opposite of the crank arms. Once they're clean, put a small spot of acrylic paint or nail polish on a chain link side plate and then another one on the face of the chainring right below it on both the front & back timing rings, using two dots or a different color on the front chainring and chain. These are now your "alignment marks". Just line up the dots and your cranks should be aligned.

regomatic

That's the mystery. We had no prior issues or malfunctions with it. The first thing I learned about tandem maintainence was the eccecntric and how the chain should be tight, but not too tight and loose but not too loose.

We never tossed the timing chain before that day, so I don't think we damaged it. And the original owners documented only about 11.5 miles before we got it, then we put near 3,000 on before this malfunction, so I think it's more related to maintainence than malfunction.

Thanks for the links to the prior posts. I'll read through them expect I'll gain additional insight to lead me towards better maintainence and repair in the future.

zonatandem

While it may be cheaper to use a less expensive/brand chain on the synchro side of the bike, in case of a problem it may not be possible to swipe a link out of the drive side of the bike . . .
Another option is carrying a extra links/connectors for each chain, along with a chaintool.
Sort of like carrying a spare tube but also a patchkit, just in case.
A possible reason for your damaged chain: someone had removed the chain with a chaintool and it was not properly re-installed, cracking the side plate a bit. Through use/stress the plate failed some more.
Glad you're learning proper maintenance, it avoid problems down the road.
Tips on chains: keep 'em clean/lubricated. Use you favorite lube method (lots of choices).
Pedal on TWOgether!
Rudy and Kay/zonatandem

Fenlason

My "guess" on what broke the chain... is that it was a just little loose and was trying to come off. A little bit of frame flex.. or some side to side motion getting a little sway in the chain going.. could have caused to to "hit" the chainring at a little bit of an angle..putting a pressure on the side links... breaking it. It could have happened without you having any idea. A little looser or a little more sway or flex.. and it can actually jam for a split second.

In addition to replacing the chain I would look carefully for any damaged teeth... you might need to straighten one.. or take a file to it to clean it up.

glenn ps sorry to be a part of the side tracking of the other thread.

Fenlason

On another forum that I was breifly on a couple of months ago...[on bikes but not specifically tandems] It was in a section of the forum where only the "expert moderators".. could reply. This "expert stated... it is a little known fact... that you can get extra wear out of a chain.. if you turn it over. like you could wear it out on one side and turn it over and the other side would be good!!!

I did not know whether to laugh or cry or??? It was things like this.. as well as a SouthPark mentality among a good part of them.. that i thought it best to just move on.

TandemGeek

In re-looking at your original post I finally realized what you actually wrote (vs. what I thought I read) regarding the photo of your old chain... that is, the section of chain you photographed isn't the section that actually broke and was, instead, one of two links that had broken side plates. As the Wizard said in Oz, that's a horse of a different color.

The only three things that come to mind which could have caused three links to fail from fatigue would be:
1 - manufacture defect, but none come to mind on these versions of SRAM chains
2 - running the timing chain way too tight, perhaps exacerbated by off-center timing rings & bio-pacing
3 - just really worn-out chains, but 3k miles isn't nearly enough to do that on a timing chain.

Of the three, #2 strikes my fancy. At least one of the posts in the selection of links I provided as well as Sheldon Brown's web page on tandem sync chains & timing rings discusses how to detect and correct bio-pacing.

TandemGeek

Actually, this is somewhat true... but only in certain applications. Tandem sync chains running on even numbered timing rings just happen to fit the criteria.

More about it can be found in my previous postings and at Sheldon's website:

Tandem Sync chains: https://sheldonbrown.com/synchain.html
Go 1/2 way down the page to the 3rd section entitled: Synch Chainrings, and the Odd or Even.

Towards the end of that section you'll find a link to his "extending chain life" article:
https://www.sheldonbrown.com/chain-life.html

Since most road tandems run fairly large diameter timing rings, e.g., 42t is common, and because not many folks mess around with their sync chains, you don't often "discover" this little known chain wear condition. However, if you happen to run smaller diameter chain rings like our 34t daVinci cranks have, or even smaller such as those used on off-road tandems, you can suddenly find that a very quiet sync chain is now making a lot of noise or even "catching" teeth after removing it for cleaning then unknowingly re-installing it with the rollers just one tooth off from where they were before you removed the chain. Moving the chain just one link left or right usually "solves" the problem.

Also, as previously noted in the chainring wear & replacement discussion buried in the end of the compact crank thread, if you "rotate" your chain timing rings to extend their life or install new ones, you also need to install a new sync chain. If you install one that is worn, you may find some disconcerting drivetrain noise coming from your timing chain rings & sync chain and the more worn the chain or the smaller the diameter of your timing rings the more pronounced it will be.

Admittedly, this is REALLY arcane stuff that 98% of the world will never know or have a reason to care about, but since it came up I figured what the heck.

Fenlason

I was aware of the idea of switch places of the timing chain chain rings. I had no idea of the problem of putting the chain back on... one tooth off and it being a problem. I do clearly understand... and am fastenated [sp] by it. Why have I not seen this before?? Most tandem riders in are area are not wearing this side out.. and of course the drive side... the chain is never in the same postion on the sprokets...so it would not show. the whole concept that only part of the chain "stretches" again is new to me.. so I need to take some worn chains and do some looking and measuring...

The even number teeth vs odd... I think I am there but I need to "look" at it another day... I am running on no sleep and no caffine... and it might help to have a tandem in front of me...

Perhaps it is because of the above..[no sleep]. but I do not see anything in any of this that indicated you get more wear out of a chain by turning it over. [of course the poster I was referring to was not talking tandem timing chains but a mountain bike drive train. ]

if you take a worn chain and measure it's "stretch" ... it does not change if you turn it over. I am sorry I do not see this at all...

and yes you are right... I am sure We have "lost" everyone else here on this forum... it is pretty nit picky.. but i find it very interesting.
glenn

stapfam

I run 9 speed and the chain for this has to be a 9 speed chain, I used to have an 8 speed chain on the crossover- but I thought about it and I now fit Shimano XT 9 speed on the crossover and drive. I now only have to carry 1 spare length of chain-Or one spare chain as I now do- and this will fit both chains.

I have always used the XT grade of chain on my MTB's and have never broken one. I use the same chain on the Tandem now and I have to admit to only ever breaking one chain. This was 5 minutes into a big ride and was a Dure-Ace/XTR chain that I was advised by my LBS was a better chain. I fitted it a couple of weeks before and it seemed OK. When it broke- I refitted the "Old" chain that had done a full year and finished the event. Checking the broken chain afterwards and a side plate had broken. Not only that but 5 more plates were about to break.
Then like a fool- I bought a Dure ace Chain for my MTB. within a few months and I broke that aswell. Dure-ace may be a good chain and I should think some of you use it- But I am afraid that it is not strong enough for our use.

TandemGeek

Your original citation was a bit thin on details so I wrongly assumed that the “turn-over” was a metaphor for managing your chain phasing on straight chain drives, perhaps tied in with the straight chain drive “trick” related to flipping chainrings to also double their life.

Given the added detail that he was talking about literally “flipping over” a chain on a multi-geared bike’s drivetrain, what he described was without a doubt bovine scatology. Hopefully he didn’t then proudly proclaim that he had done so and it “magically” worked, which would have suggested he was both inept when it came to bicycle mechanics as well as a chuckleheaded parrot, i.e., someone who unquestionably takes at face-value what they read, see, or hear to be true and then goes forth and regurgitates it as fact, without ever taking time to comprehend what they are spewing.

However, like most “urban legends, myths, and outright lies” there has to be a little truth to give the story traction and, although he completely biffed the concept, my guess is that his BS started off life at the other end of the cow’s intestinal tract as what Sheldon described in his article on, “Extending Bicycle Chain and Sprocket Life”. I’ve also seen fixed-gear riders get this odd-even sprocket phasing concept confused with fixed gear ratio selection for “skip-stopping" to extend the life of their tires.

Again, we’ve wandered way off the reservation here into drivetain esoterica

zonatandem

Have broken 3 tandem crossover chains and one single bike drive chain in 250,000+ miles of cycling . . .
Maybe we can blame the tandem chain breakage on powerful stokers?

regomatic

Let's go back to that #1;

from one of your posts linked above from 2005?

This bike was sold to me as a 2001 model that was hardly used. In fact it had only 11.5 miles on the odometer and the "new nubs" on the tires when I picked it up it up in 2005. Could it be possible that one of these "late 90's" chains found its way onto our bike and this was a total fluke?

I'm sure that we've never run it way too tight, and I will have the off-center rings checked out by the expert mechanic. I just spun it around and checked tension by hand at different locations and don't feel anything unusual, but that test would be too subjective to be reliable. We have a buyer in waiting for this bike as soon as our new ride arrives. I planned to have it checked out thoroughly and make any needed repairs or adjustments before we deliver it to the new buyers anyway, I'll add this to the list and be sure that it's corrected should any defficiencies be found.

In the meantime, I appreciate the information and responses that have been offerred so far and welcome any others. I did learn a lot about "what else do I need to know about tandem chains" from this post. This forum has provided a wealth of knowledge that has helped me move from just a rider to a more self sufficient cyclist and I'll look forward to posting more questions and sharing what knowledge I've gained more often here.

Thanks!

TandemGeek

Anything's possible, but it looks like your chains were stamped with the SRAM name and on closer inspection the model stamp looks more like PC59 than PC48.

The chains in question that were recalled were produced in '97 - '98, just before SRAM acquired SACHs (Oh, what luck, eh?). The chain models in question were the PC-41, PC-51, PC-61, PC-80R and PC-91 stamped with the SACHs name and either a date code "F" or "G".

This is a link to the CPSC recall notice: https://www.cpsc.gov/cpscpub/prerel/prhtml98/98110.html

chainedtogether

The first time I adjusted our timing chain, I learned a couple things: First, check tension with the pedals
moving. I was surprised at how much the chain rings deviate from perfect center. Mine are Gossamer
Mega Exo cranks, CNC machined. I've wondered how they could be so far off center. I don't think
they are bio pace. Is it error in the bolt pattern?

Second, when our chain is loose, the magnet on the stoker crank, for our Cateye cadence sensor,
attracts the sync chain as the crank arm rotates by. Sometimes it can stick to the chain, othertimes
just induce a little side to side wobble. It occurred to me that with a loose chain the magnet could
induce a derailment. It hasn't ever happened. I do my best to not let the chain get that loose.

ElRey

dude, you double the weight put on a drivetrain and you don't think the stress changes????

TandemGeek

While the Gossamer's chainrings may be CNC machined, the crank arms & spider they attach to are cold forged: it's the interface between the crank spider and chainrings that create the slightly non-concentric relationship between the rings, crank, and spindle. No one usually notices this on a derailleur-shifted drive train since it has no negative implication. However, on straightline drive trains like a tandem's sync chain installation it can become really obvious since you have a fixed-length chain trying to rotate about two non-concentric chainrings.

The only crankset that I know of that offers perfectly concentric timing rings are daVinci's as they use spiderless CNC'd chain rings that bolt directly to a CNC'd crankarm via a square spline. We have these on all three of our tandems and cost/weight/stiffness is comparable with FSA's carbon cranks; however, they are only compatible square taper bottom brackets vs. the newer ISIS or Octalink splined models. Here's a link to a photo that will help you understand what this arrangement looks like: https://www.davincitandems.com/images/crank3.jpg

Back to your Gossamer cranks, assuming there's a little bit of play between your chainrings and the crankarm spider arms, here are a couple extacts of my previous posts that suggest what you can do to get everything as lined-up and concentric as possible:

1. When installing or re-installing timing chain rings, make sure that you get the rings properly aligned that that the teeth are all in phase: keeping the manufacturers ring marks (brand names, tooth numbers, etc..) aligned usually accomplishes this.

2. You'll also want to try and get the chain rings centered on the spiders to remove any biopacing / cam action from your timing chain tension. Let me save a few key strokes here and, instead, once again refer you to Sheldon's Web page on tandem sync chains. The first section entitled "Adjustment" will walk you through the centering process: https://sheldonbrown.com/synchain.html

Bottom Line: If you're not having any sync chain problems with the slightly non-concentric condition then close-enough may be good enough.

stapfam

It took me a long time to get the Crossover rings adjusted so that I did not have an excesively tight or loose spot in out chain. Then I changed the chain rings to Blackburn and no problem. There is absoloutely Minimal (Daren't say None as that is impossible) up and down movement on the crossover chain. Just changing the original Chainraings to a quality pair made a world of difference.
Then on the Looseness of the chain- New chains, and chainrings will wear in. I keep an eye on the chain whenever new parts are fitted and I find that I have to tighten up after about 400 miles and then a final adjustment after a further 200. Then eventually when I get slack in the chain again- I know I have worn rings or worn chain.

Fenlason

TG I am not sure if I prefer that you just missunderstood me.. so that it ends up that we agree that turning a chain over to double it's life... is as you put it "bovine scatology [I like that]... or that you were going to enlighten me on something I did not know : )

glenn