Tandem Cycling - Unshipped timing chain at speed

Today, as my wife and I were going for a town line at 35mph on a slight downhill, curving road (the town line is a river), there was a little croink, and pow -- no resistance. Wife says "chain off". This struck me as odd, since I hadn't been shifting, but I figured it must have gone off the outside of the big chainring, so I started shifting toward the inner, and was pedaling to try to make it catch. I was completely in single bike mode, as you can tell. Finally, after getting the speed down and corner negotiated, I look down to see the timing chain bumping along the road. Ah, I thought. That chain.

We were with about 7 singles, and I borrowed two 4mm allens to both loosen the eccentric (Co-Motion) and to try to tighten it afterward. After getting the chain on, I was only partially successful in tensioning (these were tiny allen wrenches), missing my pin-spanner that I usually use. We took it easy heading home after that, to prevent another derailment.

This is the first such incident we have had in 4kmiles since last spring. I noted last time I tensioned it that there was a distinct "tight spot" where it would go tight. I adjusted the eccentric based on that. Away from that spot, it would slack off, a little more than I was happy with, but there didn't seem to be much to do.

Lately, I have been feeling a slight clunk as my left pedal went through 9 o'clock (as viewed from the left), and it has been getting worse. Attempts to track this clunk down have all failed. The wife claims she does not feel it. With today's little excitement, I have to suspect that the clunk was warning of some kind, but I still don't know what it was. I haven't yet broken it down and cleaned it up, that is tonight's project.

Any ideas on what I should look for? This whole timing chain area is the one thing about bikes that I have not spent 30 years with. It seems like if I get the distinct tight spot, I should rotate a chainring to take it out. Anything else?

A happy accident: When I put the chain back on, I didn't consider phase. As it happened, it was about stoker 135 degrees ahead of captain. I had always wanted to try OOP, but never did. This wasn't exactly a great test, but it was interesting none-the-less. Of course, the wife immediately requested that it go back to "normal". Oh, well.

Short of bending a timing ring or having a really bad chain line between the front & rear timing rings, it's really unusual for a sync chain to come off unless there's too much slack in the chain OR something got kicked up from the road like a stick... and you'd have most certainly noticed the latter as it's quite disconcerting when it happens.

Moreover, unless a non-grub bolt / non-wedge bolt eccentric like the one on your Co-Motion is really gummed-up with road crud, you should be able to rotate the eccentric enough by hand to get the proper tension, i.e, 1/2" to 3/5" of slack. It there was a problem with a bottom bracket bearings that affected the rotation of the crank spindle you'd most certainly have known that too.

Therefore, unless you discover your chain is severely worn to the point where it's experiencing some chain suck coming off your front timing ring, or a bent timing ring and everything else seems like its lined-up properly I've got to think the lower run of your sync chain ended up with a lot of slack... perhaps enough for it to self-derail from bike sway or to have been clipped by your stoker's left crank as it moved through the 9 O'Clock (actually the 7 O'Clock) position. The latter would explain the clunk but I would have expected your stoker to take note IF they were sensitive to these types of things.

As for the OOP, putting the stoker leading the captain can put a disproportionate amount of the work on the stoker. If your stoker is the stoker of you as a team, no worries, eh? However, if she's not you'd be better off experimenting with your cranks about 2 full links ahead OR leading by 90°.

I recently found a recommendation for correcting timing rings not being perfectly centered. The suggestion was to loosen the chain ring bolts on one of the rings, then barely snug them up. Following this, tap the ring with a hammer while the chain is at its tightest to move the ring a little to center it.

This did not work for me and I didn't want to continue to smack my tandem with a mallet so I managed to find a variation that I found to be much easier.

Instead of tapping the ring with a hammer, when you find the tight spot, squeeze the two runs of timing chain together with your fingers, pulling the ring to center it. It will probably take a few attempts at squeezing the chain to get it perfectly centered, for example if you overshoot the best spot and need to move it back a bit.

Once you have centered the ring as much as you think is possible carefully tighten the chainring bolts and if you still have some variation switch to the other timing ring and repeat the process.

If you tensioned the timing chain a bit more to prevent future derailment, it could be causing the popping noise as you hit the "tight spot" but I couldn't say for sure without actually seeing the bike. It could just as easily be anything Tandemgeek already mentioned.

While at the bike show, I happened to notice a vendor that makes a belt system that can be used for single speeds or tandem timing chains. It looked much less likely to be derailed, is lighter and the belts are claimed to seriously outlast bicycle chains. I haven't had a single timing chain derailment issue but I was more impressed with it being lighter and quieter.

There's a chance that rotating one or both of the rings (remove bolts, rotate ring relative to crank, replace bolts) on their cranks 180 degrees or so could reduce the extremes of chain tension and/or slack. Every once in a while rings and/or cranks are manufactured with the bolt circles off center, producing "high spots" and having these pointed away from each other uses a maximal amount of timing chain, and then 180 degrees later they are pointed at each other, and you have excessive chain slack. Rotating the ring relative to the crank can fix this.

I can remember seeing a note by Bill MacCready (sp?) somewhere, that said one of the primary causes of timing chain derailment was bent teeth on a ring. Seems to me a competent team would notice that. I'm inclined to go with the chain slack theory.

In the past, I think pointy-toothed rings were made for singlespeed / track / timing ring use, instead of the more common flat-topped rings with which we are more familiar, which would be less likely to allow the chain to derail.

for getting he chain back on: how about taking off a chainring so that you don't have to mess with the eccentric. put the chain on the unmounted ring ant then rebolt the chainring

Some update here. Rode it today for 47 miles after re-tensioning the eccentric. It was smooth, no sign of clunk. The eccentric is almost at its full forward position; I plan to replace the timing chain this winter. This is the original timing chain, with less than 5k miles on it.

While tensioning, there is definitely a high tension spot. Another rider on the ride today (also a tandem owner, suggested the loosen-chainring-bolt trick to remove the eccentricity of the chainrings. I may also try to mount a dial indicator to see if I can determine where the problem lies and try to correct it directly.

There are no apparent bent teeth; I was looking for that. There is a gentle side-to-side wobble, but not enough, I think, to create a horizontal wave in the chain.

Thanks for all the advice; I will report back anything interesting, but right now I think it must have been a combination of a bumpy road, a lot of load cycling, and a loose chain.

I had the high low problem too.
I put a new chain on, loosened the chainring bolts on both front and rear slightly, kept tension on the chain and rotated the chain a few cycles and everything seemed to center-up.
Tightened the bolts and properly tensioned the chain and high/low spots were gone.

I am going to bookmark this thread as there has been a wealth of useful tips presented here.

I am new to tandems, but in my experience 4000 miles is more than enough to lengthen a chain, and without something to put constant tension on it --like a derailleur-- a worn chain can climb up on the teeth enough to come off every now and then. The problem will get worse over time.

My folding bike has somewhere around 4000 miles on it, and it's on its third chain. It came off twice last week, and once the week before; I expect I'll be replacing it again this month.

I am new to tandems, but in my experience 4000 miles is more than enough to lengthen a chain, and without something to put constant tension on it --like a derailleur-- a worn chain can climb up on the teeth enough to come off every now and then.

Which is why the eccentric should be adjusted periodically if needed to take out the extra slack along with my previous suggestion for "centering" the rings. I seem to remember reading some recommendations for tandem chain life and for the drive chain it was nearly half that of a single bike with the timing chain lasting over twice as long. 4000 miles does sound about right for the upper limit, however I would not expect there to be issues with the chain derailing assuming proper adjustment of the eccentric.

I am going to bookmark this thread as there has been a wealth of useful tips presented here.

+1. Our daVinci has two timing chains, so I'm typically fighting two tight spots! Looking forward to trying these tips out.

I would think that timing chains should have less of a life span than the drive chain, especially if tight spots exist that stress the chain prematurely. I know on our singlespeed single bikes the chains have generally had less life than our geared single bikes.

I would think that timing chains should have less of a life span than the drive chain, especially if tight spots exist that stress the chain prematurely. I know on our singlespeed single bikes the chains have generally had less life than our geared single bikes.

You might think that, but it's not a correct assumption. The sync chain serves one purpose and that is to transmit the front rider's power to the rear bottom bracket spindle and it does so on conventional tandems through a 1:1 direct drive system using, in most cases, relatively large (34t - 48t) chain wheels or, as they're more commonly referred to, timing rings. So, you have only one rider's energy going into the system.

Now, to be fair, your daVinci is an exception in that your sync chain is subjected to higher loading than a conventional tandem without the small BMX freewheel sprockets used by your Independent Coasting System's jackshaft. However, even so, the loading is still not all that much more severe than a single speed / single bike since you don't ever end up working against a stoker with an inefficient pedal stroke.

Now, let's look at the drive chain: it must handle the power of both riders on a variable gear system that uses sprockets with as few as 11 teeth and, for triples, granny-gear ratios on 27t - 34t sprockets, and that must also deal with side loading and wear from the front and rear derailling process.

As for "high spots" stressing the chain, you'd have to use a pretty large lever to tighten the eccentric enough to get anything close the amount of loading on the chain as it sees when it's under load from normal pedal input by the captain, never mind how much that chain loads up when the captain is standing on the pedals and climbing or sprinting at a maximum effort.

Yes, the high spots are annoying and very disconcerting when you spin a tandems drive train without any kind of a load on it but that's abo

I am going to bookmark this thread as there has been a wealth of useful tips presented here.

Bookmark this instead: http://sheldonbrown.com/synchain.html

... right now I think it must have been a combination of a bumpy road, a lot of load cycling, and a loose chain.

Based on what you have described, I would tend to agree with your conclusion.

for getting he chain back on: how about taking off a chainring so that you don't have to mess with the eccentric. put the chain on the unmounted ring ant then rebolt the chainring

:eek: You're kidding, right?

Here are the three easiest methods I know of for pulling the sync chain off a tandem.

1. Leave enough chain slack (3/4" - 7/8") so that you can manually derail the chain by hand as you turn the cranks to advance the chain... being careful to keep your fingers out of the gear mesh. Reinstalling is simply the opposite: get your cranks aligned and then counter rotate your cranks to re-engage the chain on the front timing ring. Yeah, you might nick a chain ring tooth every now and again but that doesn't really bother the sync chain and, even then, you can usually knock it down with a few strokes of a flat file.

2. For non-outboard bearing users who have square taper, ISIS, or Octalink bottom brackets, install self-extracting crank bolts on one or both sets of cranks and use a hex wrench to pull off one of the cranks to free your chain while still installed on the crank and timing ring. Note: If your sync chain is too tight this won't work... well. For bottom brackets with outboard bearings, consult your owners manual.

3. Just learn how to use your eccentric, have the necessary tools to use it in the field, and service it often enough to keep it from getting seized in the eccentric shell.

The last little trick to make all of this really easy is to put some alignment marks on your sync chain and timing rings, e.g., a couple of colored "dots" of paint so that you don't have to guess if you've got everything lined up. A blue dot of paint on the front ring and an adjacent chain side plate and a red one on the rear ring and chain will do it.

There are actually some other tips in addition to these out there in the archives in one of my posts from way back when; however, the search engine seems to be acting up (along with the entire BF server) so that'll have to wait for another day.

Me? I use #2 the most often, followed by #3 and #1 when I'm lazy or in a hurry.

Both our sync chainrings are tweaked on the beater tandem, so I pulled off the rigid tensioner and put on an old crusty rear derailer in its place. Seems to work fine now even with the tweaked chainwheels. IIRC I got the idea from a pic of one of Sheldon's tandems. Spring loaded tensioner FTW.

:eek: You're kidding, right?no way. i never had it happen (yet). but to me, one 5mm allen to take off 5 bolts seems easier to than trying to pull a crankarm off on the side of the road or messing with the eccentric. not that it's difficult to adjust the eccentric, i just think the other way is easier. and even though i have the basic shimano crankset, the timing rings are nice dura-ace ones which are very round and i don't have to play with the location of the chainrings to set the chain tension even (so far).

but to me, one 5mm allen to take off 5 bolts seems easier to than trying to pull a crankarm off on the side of the road or messing with the eccentric.

Completely removing 5 crank bolts is easier than loosening two allen bolts that hold the concentric in place and adjusting it with a spanner? If it happened to me on the road, I think I'd just opt for rolling it back into place since there would appear to have been enough slack for it to roll off. I don't foresee that happening though since finding the tip on centering rings.

Completely removing 5 crank bolts is easier than loosening two allen bolts that hold the concentric in place and adjusting it with a spanner?

You've brought up a good point that I failed to even take into consideration in explaining why I placed adjusting the eccentric 3rd instead of 2nd on our tandems... and that point is different brands and even some different brand's models of tandems have different types of eccentrics.

Our tandems presently use the internally-expanding Bushnell eccentric which is adjusted using a single hex wrench that is accessed from the right side of the front bottom bracket. While these are very easy to adjust with a T-wrench or hex-head socket & ratchet, they are nearly impossible to adjust with a micro-tool because of interference from the crank arm. Therefore, at least out in the field, it's just easier to pull a left-side crank that's been fitted with self-extracting bolts using a single 8mm hex wrench: no crank puller required.

The original Calfee eccentric can't be adjusted on tandems with outboard bearings and even some types of square or splined bottom brackets that have very large fixing cups as they both block access to the bolt heads. The newer Calfee eccentrics are larger and move the bolts further away from the spindle so that they can be adjusted on tandems that use the outboard bearings.

Santana's tandems use two grub bolts that are accessed from the underside of the eccentric which makes them very easy to access. However, they do tend to allow grime to build up in the gap between the bottom of the eccentric and the shell which can make rotating them by hand a little tougher than some of the other designs.

Older Co-Motions and a lot of the other brands of tandems use a pair of pinch bolts which, like the Santana eccentrics, are very easy to access and because the eccentric shell is pulled tight around the eccentric, there aren't any gaps where grime can build-up so these too are very easy to rotate by hand. I believe certain models of newer Co-Motions now use an internally expanding eccentric which may require a T-wrench similar to the Bushnell.

Trek and Cannondale use a wedge-type eccentric which can be a real bugger to adjust out in the field. In theory, the single bolt accessed from the right side of the eccentric gets unscrewed just enough to bring the head of the bolt out past the eccentric shell and then you whack it with a blunt object to break loose the wedge that holds the eccentric in place. In practice, the wedges can get stuck if too much torque is used to tighten the wedge bolts... usually as owners or shops work to eliminate creaking noises. Therefore, it can become a challenge to loosen these things in the field.

So, the point here is... there may be other factors that make adjusting the eccentric a less desireable option for field adjustment or a quick fix even at home. For me, when I'm at home the Bushnell eccentric adjustment is a no brainer: stick the T-wrench in and loosen it up. If I was smart I'd just carry a cut down T-wrench for field repair but, as already noted, I tend to cheat and just roll the chain off by hand, even if it might nick a tooth on the front timing ring.

I believe certain models of newer Co-Motions now use an internally expanding eccentric which may require a T-wrench similar to the Bushnell.
The one we have has 4 x 4mm socket head screws (2 per side). It is normally a very easy thing to deal with: you only need to torque one screw to hold it. But you need a pin-spanner to get a good handle on moving it. Using 2 micro 4mm's in the field (literally) didn't work too well.

One thing I don't like about the Co-Motion eccentric design is that when it is free, it slides really easily from side to side, so you have to worry about that when tightening it. Overall though, I think it is one of the best ones I have seen.

Trek and Cannondale use a wedge-type eccentric which can be a real bugger to adjust out in the field. In theory, the single bolt accessed from the right side of the eccentric gets unscrewed just enough to bring the head of the bolt out past the eccentric shell and then you whack it with a blunt object to break loose the wedge that holds the eccentric in place. In practice, the wedges can get stuck if too much torque is used to tighten the wedge bolts... usually as owners or shops work to eliminate creaking noises. Therefore, it can become a challenge to loosen these things in the field.

Your information may be a bit dated, unless I'm misunderstanding. My 2005 Trek tandem has a thrucap that screws in behind the wedge bolt - a short screw with a hole through it that allows access to the wedgebolt. When you loosen the bolt, it backs into the cap and provides a base for the bolt to force the wedge out. Whack 'em is history, unless one gets seriously corroded into place. I believe the current Cannondales work the same way. As it happens, I've almost always used my (largish Topeak) minitool to adjust it, simply because it's handy. Haven't had to correct a derailed timing chain yet, but can see where some interference could come into play. Pulling the crankarm could be a handy trick - I'll have to keep that in mind.

As for the chainring trick: I've tried that once on the fixie when I forgot an axle-nut wrench and couldn't seem to roll the chain back on. Never again. It was one of those jobs that required more hands than fit in the space, and the tension on the chain made it hard to get the ring mounted concentrically. I can't imagine that a timing chain would be much easier, unless it was also loose enough that it would roll on without difficulty.

Your information may be a bit dated...

Most likely... My C'dale was a '98 and it does appear they finally ditched the original design (http://www.google.com/patents?id=pR5UAAAAEBAJ&printsec=abstract&zoom=4#PPA1,M1) for one that works better... much better just looking at the design (http://www.cannondale.com/asset/iu_files/techcenter/2004_eccentric_double_wedge_owners_manual_supplement_en.pdf).

Same thing goes for Trek; a quick check of the manuals does seem to suggest it uses and improved eccentric design.

Thanks for the course correction.

Hadn't seen the internals of the new Cannondale; that's right fancy. Not completely crazy about the circlip, but the dual wedge is a nice add.

Suppose it doesn't matter how good Trek's is; at least not for 2009.

Suppose it doesn't matter how good Trek's is; at least not for 2009.

It was apparently a supplier-related issue that couldn't be resolved. Hopefully they'll get things worked out.... as I kinda like having some downward pressure on the price point of nice tandems.

Hadn't seen the internals of the new Cannondale; that's right fancy. Not completely crazy about the circlip, but the dual wedge is a nice add.

My experience was that the clip doesn't last very long. There is too much pressure on it. So, we're back to wacking it.

A little bit of update here. I am doing a complete overhaul of my Co-Motion now and have also obtained off ebay a spare crankset (FSA Gossamer). I discovered that the bottom bracket spindle lengths are all over the place; in particular, the ones on the bike when the unshipping happened were 108 on the front, and 118 on the back (FSA Platinum ISIS). This could have been a contributing factor, though of course tension is the key thing.

Anyway, the strange thing is that the spare set includes two FSA Platinum 113mm spindles. I was kind of hoping that I would have spares for any location, but that would require making the front and back the same, and thus keying everything off the stoker/triple requirement (as discussed in other threads). So maybe I just have 2 spares for the captain BB. Which is a bummer, because I think I need spares for the stoker BB; it doesn't feel too good when turned by hand, though with the crankset on it is hard to feel a problem.

And something I don't understand about these "new fangled" BBs. I thought the whole idea was that they used common sealed bearings. But nobody seems to replace the bearings, which would be much cheaper. What is the story there? (feel free to point me off to some other site)

And something I don't understand about these "new fangled" BBs. I thought the whole idea was that they used common sealed bearings. But nobody seems to replace the bearings, which would be much cheaper. What is the story there? (feel free to point me off to some other site)

No, the whole point of changing design specifications is to make existing things obsolete so that consumers will buy the new things instead of simply maintaining the old ones.

Every once and a while something gets slipped in that's actually a legitimate improvement but that's the exception and not the rule.

Only 4,000 miles on a crossover chain? Unless you do lots of dirt/rain/trail riding and don't clean your chains at all, that is darn low mileage.
The eccentric is supposed to take up excess slack in chain . . . 10,000+ miles on a crossover chain is more like it.

No, the whole point of changing design specifications is to make existing things obsolete so that consumers will buy the new things instead of simply maintaining the old ones.


+1

Not to mention making things that wear out faster so that "lifetime" items become "consumables".

Trek and Cannondale use a wedge-type eccentric which can be a real bugger to adjust out in the field. In theory, the single bolt accessed from the right side of the eccentric gets unscrewed just enough to bring the head of the bolt out past the eccentric shell and then you whack it with a blunt object to break loose the wedge that holds the eccentric in place. In practice, the wedges can get stuck if too much torque is used to tighten the wedge bolts... usually as owners or shops work to eliminate creaking noises. Therefore, it can become a challenge to loosen these things in the field.

So, the point here is... there may be other factors that make adjusting the eccentric a less desireable option for field adjustment or a quick fix even at home.

I have a new-to-me Trek 2012 with a seriously seized EBB (both aluminum). To boot, it wasn't adjusted properly in the first place and throws the chain a LOT. Teaches good technique trying to pedal smoothly and keep it on. My mechanic tried everything short of a torch. I'm gonna try soaking it in ammonia and then some hot-cold cycles. And then a bigger hammer. And then lots of copper/aluminum/graphite anti-seize.

In trying to get it to turn, I used a trick that might be of use when adjusting the EBB in the field without a pin-spanner: stick a long allen wrench in one of the pin-spanner holes and then back the crank (non-drive side on this) against it - the distance between the crank spindle and the wrench makes a pretty good lever-arm to twist the EBB. Long enough that I broke the end off of an alloy wrench, since the EBB was seized so tight.

I have a new-to-me Trek 2012 with a seriously seized EBB (both aluminum). To boot, it wasn't adjusted properly in the first place and throws the chain a LOT. Teaches good technique trying to pedal smoothly and keep it on. My mechanic tried everything short of a torch. I'm gonna try soaking it in ammonia and then some hot-cold cycles. And then a bigger hammer. And then lots of copper/aluminum/graphite anti-seize.

In trying to get it to turn, I used a trick that might be of use when adjusting the EBB in the field without a pin-spanner: stick a long allen wrench in one of the pin-spanner holes and then back the crank (non-drive side on this) against it - the distance between the crank spindle and the wrench makes a pretty good lever-arm to twist the EBB. Long enough that I broke the end off of an alloy wrench, since the EBB was seized so tight.

You might consider reposting this as a new thread - might get more looks.

Sorry, I have no advice. Surprised that a nearly-new bike would have seized parts already.

We've seen timing chains on others' tandems come off. Loose chains. We've also seen a stoker rip off the leftside FSA crank. Untorqued bolt. Clipless pedals proved their worth once again. It is definitely good to have an 8mm allen wrench.

Please, no hammering!!!!!

If the current Trek EBB is similar to the older single-wedge design, there are excellent instructions in the FAQ for the tandem@hobbes list: http://hobbes.ucsd.edu/tandem/Maintenance.faq . The instructions refer to Cannondale, but the older Trek EBBs were the same. If it's a double-wedge, you may be able to use the instructions on one side at least. Or, there may be a circlip in the bolt bore on one wedge so that after the bolt is loose, you continue to loosen it until it hits the circlip, and then keep on loosening while it pushes the wedge out.

Here's the section from the above link on loosening the EBB:

"2) Loosening the wedge.

(If you are going to be overhauling the bottom bracket, remove the crank arms
and the cartridge first.)

The Cannondale uses an expending wedge eccentric, similar in design to a handle
bar stem. The bottom bracket shell is a featureless aluminum cylinder. The
bottom bracket axle is mounted in a aluminum rod whose outside diameter is
slightly less then the inside diameter of the shell. The axle is mounted
off-center ("eccentricly"), so that rotating the holder (the "eccentric") moves
the axle fore-and-aft (and slightly up and down). A diagonal cut is made
through the cylinder, producing a wedge shaped piece. A nut is mounted in the
wedge, and a countersunk hole is drilled through the eccentric from one end
through to the wedge. A bolt is inserted into the hole and threaded into the
wedge nut. When the bolt is tightened, the wedge is pulled into the bottom
bracket shell, causing the effective diameter of the eccentric to increase,
wedging it into the shell.

The common and wrong way to loosen the wedge is to back the bolt out so that
the head is exposed, and pound on it with a hammer.

To loosen the wedge the right way, you need a short bolt with the same
threading as the wedge bolt and a stack of a couple of washers, of increasing
sizes. The bolt, with the stack of washers, is inserted into the eccentric from
the wrong side, i.e., into the big end of the wedge (on the right side of
tandem), and threaded into the wedge nut. The largest washer should be large
enough to bridge across the large end of the wedge from the bottom bracket
shell to the eccentric. Now, when this bolt is tightened, it gently pulls the
wedge free. When the wedge is free, remove the bolt and washers, and put them
in your on-bike tool bag.

The next step is to show this to your local bike shop mechanic, so that he
stops pounding on frames with a hammer."

Lots of technical discussion. But sometimes the simple stuff can be overlooked. I didn't see (unless I missed it) much discussion about the BBs themselves. Worn bearings can introduce enough free play that the crank spindle can be wobbled by hand. Loose chainring bolts can make a chainring wobble. Poor chain line can encourage a tooth to catch the side of the chain.

. . .and another option for a loose crossover chain if you want to tighten it up a bit without messing with eccentric (which on some old models are a bit of pain, including C'dale/Trek) is to 'float' a spare chainring a couple teeth larger than the cross-over rings.
Yes it works (did it in the early 80s) and it will lead to some interesting exchanges with other riders, like 'it'will fall off!' or 'why'd you do that?'
Yes, with proper care (clean/lube) cross-over chains will last twice as long as drive-chains. 10,000+ miles for us is pretty well standard.
Just our input.
RUdy and Kay/zonatandem