Tandem Cycling - Shifting Problems
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05-27-07, 08:03 PM
I bought a Calfee Tetra Tetra tandem in March '07 and have been very happy with it overall. I have Durace shifters and front derailleur, XTR rear derailleur, and yes, IRD 11/34 rear cassette. We have now put about 765 miles on it and still am trying to get the shifting right.
After determining that the cable housings were too short and the cables were sticking, new housings and cables were installed which improved the shifting somewhat at 600 miles. It no longer threw the chain off the small chainring onto the frame, which it did 5 times before, even with mulitiple derailleur adjustments.
What is working well: The chain goes on the large chainring very well on upshifts.
What is working some of the time: Downshifts ok from the large ring to the medium chainring.
What is not: The chain seems to "skate" much too often when going from the middle to the small chain ring, and from the small to the middle chainring. The pedals seem to freewheel when in this mode. It does appear that the chain is in a gear on the rear cassette, but just doesn't quite get in the grooves on the small and midside chain rings. Once in a while it also skates from the large ring to the medium.
Also, when shifting from the small ring to the medium chain ring, I have to push the shifter twice to make it go on the ring. It does go easier to the small ring from the medium but again, sometimes skates and I have a hard time getting it to catch.
The rear cassette shifting on upshifts goes fine, but on downshifts there is slipping and trying to find the right gear with the resultant gear noise as it strives to find the correct rear gear.
Is this a cable problem, front derailleur problem, bent chain link(s), possible (but hard to believe,), captain error? I am trying to be conscious of location of chain in rear cassette before shifting so as to avoid extreme chain angles while shifting.
Thanks for your input! I am going to TTR on Thursday and hope to get this nailed down.
05-27-07, 08:57 PM
Had similar issues on our c/f Zona tandem utilizing DuraAce STI. Front shifting was problematic (similar to yours), rear shifting was A-OK.
Fought with the front der. shifting for 3,000 miles. Even stoker Kay got fed up!
Her comment: Hey we've been using barcons for almost 30 years on our tandems . . .
Went to Dura Ace 9 speed barcons . . . now have 14,000+ miles on that Zona . . . problem eliminated!
Lo-tech out does hi-tech in some instances!
Pedal on TWOgether!
Rudy and Kay/zonatandem
05-28-07, 09:55 AM
It sure does sound like excessive cable drag/frictin but, because you're having problems both front and rear, you might try replacing the chain (the one component that affects both) -- perhaps with another brand or model. When in doubt, Shimano is probably the best fall-back for an XTR/DA system. HOWEVER, As Tandemgeek is wont to remind folks, it is almost impossible to diagnose some problems "over the phone." Once you've reached the end or your abilities, the _best_ approach is to find the most competent professional wrench in your area and pay him or her what it takes to get it right.
One thing I can say with confidence is that the cause is nothing inherent with STI or 10-speed (you don't say, but the IRD cassette suggests that's what you've got). Both can work extremely well on tandems, even if bar-con shifters can be a bit easier to "dial" on some bikes.
05-28-07, 07:45 PM
Thanks for your comments - I appreciate your help. I am going to buy another chain to see if that helps as today my friend Greg(BloomingtonCyclist) and I worked on it for awhile with some improvement but it still skates between the medium and small.
What is especially frustrating about trying to fix these kind of issues is that it putting the bike on a workstand just doesn't match real world riding up a steep hill!
Curious what the LBS has said. I suggest putting the bike on the trainer at the shop and ride it under power and show them the problem so that they can make adjustments. If you did the build yourself, you need a trainer to put the bike on and put it under load to diagnos problems.
The other thing that I have found is that the 10 speed technology can be sensitive to chain position on the rear cassette prior to shifting the front der. This is true on the tandem and our two road bikes. If you are shifting to the small chain ring from the middle, position the chain so that it is slightly cross chained in a higher gear not a lower gear. This is not how one would ordinarily operate. Normally, one would select the middle chain ring and keep downshifting as one needs a lower gear. When you decide to shift to the small chain ring, shift down a couple of gears on the rear cassette and then shift to the small chain ring. This should put you in approximately the same gear ratio and then you can shift the rear der to a lower gear. One would think that the technology should just work from all gear positions. It may if you fiddle long enough with the adjustments. This technique worked for me and there is an advantage in that once you get used to it the shifting is fast and the cadence does not change dramatically when you shift the chain ring. I use the same technique shifting the middle chain ring to the large – two quick up shifts on the rear and shift to the large chain ring.
FYI…I put an 11/23 10 speed Ultegra cassette on my tandem and the shifting is really crisp. The 11/34 that came with the Santana is fine but this set up is even better for both the front and the rear. This tells me the front is sensitive to chain tension. We will see if this remains true over time or was just my imagination. We rode 44 miles today with our usual course with 2500 feet of climbing and the 11/23 worked great.
05-29-07, 04:48 AM
Indexed shifting is bad. Go back to friction! (end retrogrouch mode)
05-29-07, 07:04 AM
[QUOTE=Lo-tech out does hi-tech in some instances!
Wisdom of the ages from a perpetually young guy named Zona. Remember when you could open the hood of your car and just about climb inside and get to everything, and fix it without a $20,000 computer station? How many pro chefs use electric stoves with printed circuit boards that decide when and when not to pulse the burner? And the old fashioned electro-mechanical switches on everything from dishwashers to toasters that just seemed to work and that could be replaced without emptying your wallet (or sending the thing to the landfill in favor a new, cheaper solution)? And the newest grin called the MS Vista operating system that has taken bloatware to a hilarious new dimension? Remember when we all did just fine with 5,6, and 7 cog cassettes that could all be used with just about every chain ring?
Perhaps as we move toward a "green" revolution, simpler stuff will once again be in vogue. It could spark whole new cottage industries.
I like the (9-speed) STI rear shifting system. It is handy. But I will be going to a barcon friction shifter for the front der. this year.
05-29-07, 09:27 AM
Too hard to know without fiddling with it.
I'd be as inclined to look at technique as the hardware as it could be one or the other or a combination of both, e.g., is your stoker "easing off" on the pedal pressure a tad as you shift or does she continue to drive the pedals?
What are the brand & sizes of the front chain rings?
What brand and model of chain are you using?
Is the derailleur cage parallal with the chain rings or slightly canted in or out?
How many millimeters are there between the bottom of the derailleur cage and the top of your big chain ring's teeth when it passes over on the shift from big to middle?
05-29-07, 10:47 AM
The other thing that I have found is that the 10 speed technology can be sensitive to chain position on the rear cassette prior to shifting the front der. ... One would think that the technology should just work from all gear positions. It may if you fiddle long enough with the adjustments.
That's not been my experience with 10-speed STI at all. It's no more finicky on our tandem than 9-speed was -- that is, not finicky at all, once I sorted it out. But I didn't change the front 'rings or derailleur when I changed from 9 speeds to 10. We still have the original Ultegra items... which reminds me of a conversation I had with a drivetrain engineer at one of the better-known bicycle companies. He remarked that, as part of the 10-speed evolution, Shimano seemed to have put more technology into chainrings and less into derailleurs. He felt that it may have been a reaction to the increasing number of crankset competitors and an effort to encourage bike makers to stick with all-Shimano drivetrains instead of spec'ing Shimano derailleurs with brand T(ruvativ) or brand F(SA) cranks. Assuming my source is at least partly correct, you might look to see if you have genuine Shimano rings and, if you don't, see if you can try some without actually investing in them (which could cost a pretty penny).
05-29-07, 08:42 PM
Thanks to all for your posts. To TG, I will get you the measurements tomorrow. The ring sizes are 30, 39, and 53 - FSA Mega Exo carbon crankset. I am going to be getting a new chain just to make sure that that isn't causing the problem. I am now using a Shimano - will try and get a Shimano Ultegra chain.
05-29-07, 09:00 PM
I have FSA/Ultegra 10 Speed on my Santana and shifting is outstanding.
I understand this is not your issue but the one time shifting was poor turned out to be my technique - Shifting from small to medium ring, I was not pushing the lever all the way across thinking I would push to far to the top ring. As soon as I recognized my mistake and use full lever deflection for shifts from small to medium and medium to large. My stoker raves how cleaner shifting is on 10 speed vs 9 speed.
I have had no issue shifting down big to medium, medium to small.
In my humble opinion, if you still have an issue after swapping chain and rings all that is left is your lever. With the utmost respect to zonatandem, I do not believe switching to bar end shifters is needed to get perfect shifting.
05-30-07, 08:54 AM
...I am going to buy another chain to see if that helps as today my friend Greg(BloomingtonCyclist) and I worked on it for awhile with some improvement but it still skates between the medium and small...Counselguy
As Counselguy said, we were able to work on the front a little bit. My wife and I rode it a few weeks ago for about 15 miles and at that time it skated on the small front ring when we shifted to it in prep for a major hill. On our own tandem, we've had some occasional skating when shifting from the large to middle chainring - we never had this with the original KMC chain - it only started after putting on an Ultegra 10 speed chain which is narrower than the original KMC chain. It has made me wonder whether the slightly thinner chains can have more skating problems on cranks that are made to supposedly work with both 9 and 10 speed systems...just a thought. However...
...there is one aspect on counselguy's tandem that we saw when we worked on the bike the other night and I believe is contributing to or possible causing all of his skating problems and after I describe it, jump in with your advice (I might be wrong). First, there is a boss with a threaded post low on the base of the seat tube to be used for attaching a fender. The threaded post has a nut (with nylon insert) on it leaving a couple of mm of threaded post exposed before the post goes into a The front derailleur cable passes under the bottom bracket through a tunnel made in the massive carbon fiber wrapped joint and exits an opening behind the base of the seat tube going on up to the derailleur. Unfortunately, the exit opening is centered in the space between the chainstays instead of being closer to the drive side chain stay. When the front derailleur is on the middle or large ring, the cable clears the fender mounting boss just fine but when the derailleur has shifted to the small inner ring, the cable is against the fender mounting boss between the nut and the base of the boss or it hits on the base of the boss itself. Either way, it deflects the cable plus the deflection is a little different depending on which part the cable is rubbing against. I believe this is messing up attempts to get the front derailleur to behave consistently when shifting to the inner ring. If it always rubbed in the same place I believe it would be easier to compensate for but as I said, the cable hits in one of two different places and it appears to me that they cause slightly different amounts of tension to stay on the cable.
So, it's a defect in the design / build but I'm looking for a fix. I have been thinking about ways to make a cable guide to keep the cable in a good position away from the boss. I first thought of threading a small tube to put over the post and base and let the cable rub against that. I've also thought about getting someone to braze a thin stainless tube to the side of a nut and then thread the nut on the post (with another nut against it to hold it still) and have the stainless tube be a cable guide (it could be bent / shaped to provide a good transition from the bb opening towards the derailleur.
The shop he bought the tandem through is several hours away in Cleveland although I believe that they have the ability to do some machining. I'm pretty sure that the thought of being without the tandem long enough to send it back to Calfee where reworking the cable tunnel under the bottom bracket would seem like starting from scratch -- so that's why we're trying to think of some things we can do here in Bloomington, IN. I'd post a photo if I had one, but I may take some if this isn't making sense to readers.
So, it's a defect in the design / build but I'm looking for a fix. I have been thinking about ways to make a cable guide to keep the cable in a good position away from the boss.
I suggest posting this problem on the Calfee forum with a pic http://www.bikefanclub.com/forum/postlist.php/Cat/0/Board/calfee . If it is a design defect, other owners will have it, will have work arounds or the problem is unique to counselguy's frame / build. I suggest sending a pic to Craig Calfee and get him on the phone and to the LBS prior to any substantative changes to get their solution/advice. Good luck.
05-30-07, 10:39 AM
So, it's a defect in the design / build but I'm looking for a fix.
Probably not. As already suggested, the Calfee Owner's Forum archives would yield similar problems if there was something afoot related to the frame vice the components that are attached to it and having already checked there I'm just not seeing any. Moreover, unless there is a lot of cable deflection, I'm having a hard time imaging that it would create the problems as described on the front derailluer: rear, yes... front's just aren't that precise except when it comes to trimming.
However, if you still are having issues when you arrive in Tennessee look for me. I'll have my "stuff" with me as I usually do at rallies and I've got teflon sleeves that can be used to eliminate any friction between the FD cable and fender stud. That should help to isolate cable interference as a potential issue. We can also verify that the spacing on the chainrings is correct, etc...
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