Help! Tandem triple chainring shifting issues

[Tom Rodgers]

Dear LSR friends:

Since so many of you ride tandems and/or use triple-chainrings on a touring bike for thousands of clicks, I have some questions. My wife and I have been back on the tandem for about six months and did okay in the Texas Time Trials six-hour ride. I have a lot of experience building and fitting road and triathlon frames, but not as much with a triple chain-ring and definitely not on a tandem. We have an older frame and drivetrain we bought with Ultegra 9-speed, and we really do not miss the 10th or 11th bear, and generally speaking, ultegra is a reliable system. The rear cogset is 11-32 and shifts just fine in all gears. 

The problem comes with the front triple, which is 32-44-54 with a 175mm crank set for me (170mm for wife on stoker). This works good for me as captain because I'm used to 175mm and a 54-tooth big ring on my road and time-trial bikes, and with the 32x32 front-rear selection we can climb longer 15% grades reasonably well. The most unreliable aspect is going from the 44 ring to the 54 ring, usually after climbing and then wanting to go back downhill in 54x11, one of the funnest parts of tandem riding, descending very fast after a slower tandem climb. It just will not a reliable jump into the 54-tooth ring, no matter how much adjustment I've done. I have 20 years experience configuring Shimano an SRAM chainrings and shifters, going back to 9-speed non-indexed left shifter lever and of course newer STI shifters, so I know most of the quirks of adjusting a front derailleur and tensioning the cable. No matter how good I get the front derailleur and left shifter working on the bike stand at home, at some point in a hilly ride, it becomes very difficult to move to 54. Sometimes this means riding a lot in 44x11 when we'd rather be in 54x11 or 54x13. About the only way to make it go over is to get off the back and do it by hand, or sometimes by waiting a long time in 44x11 with chain rattling until it goes drops in spontaneously. Of course, once I get home and reset the cable again, everything seems to work fine. Also, after several hours of finagling, I'm 95% sure the left derailleur is mounted correctly, no way to get it move rather right with the chain (cage would actually hit the crank). There just is not that much room for error or adjustment on a Co-Motion Tandum with an Ultegra triple. It's meant to fit about only one way with maybe a millimeter and/or a degree of variation, not nearly as much room to play around as with a 2x10 road bike setup.

So I wanted to ask some questions about how you actually ride with the triple and/or tandem:

1. When I have been using a double, at least in the old days before electronic shifting, it was not a good idea to ride much at all in something like 53x23, because the chain would rub against the derailleur cage. You could shift into that okay most of the time, but not a good place to be for more than 100 meters or so of riding, inefficient. I try to follow that rule with the tandem, but because it's so hard to go from 44 to 54 chain ring, I find myself having to stay in 54x32 even though it's not the most efficient choice. How often do you even use your biggest ring on your tandem in easier brevet-paced riding? 

2. Do you find yourself riding more and more in the middle ring (for me, 44 teeth) and only using the larger (53 or 54-tooth) ring for cogs like 13, 12, 11? In other words just for longer downhills. 44-tooth for me is like a pro-sized time-trial bike small chain ring, and I have done this a lot, just not so much as required with the tandem.

3. The biggest problems seem more frequent after a longer time spent in 32 ring climbing 11-15% grade with 32x32. That seems to make it harder to EVER get the derailleur back to far-right into the 54 coming down the hill.

4. My Ultegra 6503 front triple derailleur is not very worn at all, an older model but very little wear with strong springs. The cable is also relatively unworn, but I'm going to get a new 3000mm cable this week because I've frayed the derailleur end of the cable due to so many adjustments and attempts to make it work right.

5. I do have an external cable tensioner barrel on the left captain side to tension it more, but this works for early home rack setup, but tends to become less helpful after hours of riding.

From a modern perspective, I can fix all of this by going to a 2x11 electronic front shifter, either SRAM etap (preferred) or Shimano, but this make it harder to go with 32-tooth front ring, which we DO need. We can't just go with 34x28 to climb, just not enough, or even 39-42 tooth ring. There aren't any 2x ring setups that can jump from 32 to 52,53, or 54 tooth front ring. If this were a solo upright touring bike the 2x11 electronic would be the solution for me, but not for my wife on a tandem. Because we have 9-speed rings and cranks, the 2x11 or even 3x10 means spending $2,000 for an all-new electronic drivetrain, including two new cranksets with rings for the narrower chain. By the time we do all that, we might as well upgrade the whole bike, but we bought this one on eBay eight years ago and it still works great, not ridden much between 2009 and early 2017. If we were 20 years younger and weighed 40 pounds less for both riders, maybe 2x would work for us, but that's not going to happen.

So I'd like to find a practical way to keep riding the 9-speed triple, which is plenty of gears but currently unreliable to the big chain ring. I've already got a newer front derailleur, and could even get a newer Ultegra left STI shifter for triple, but I'm not really sure I need it. Maybe there is some strategy to use in shifting during rides that avoids this problems? I'm even thinking of installing an older aerobar non-indexed left shifter from one of my original 1999 triathlon bikes (we have aerobars on the tandem) and just seeing if I can "feather" the front ring shifts better than index triple STI shifter--weird solution, but might work if can't find a better way.

Another reason this is so different for me is that I'm using to doing a 200km brevet averaging 20+ with 54-42 front rings even on our hilliest courses with no problem. Tuula and I are more like 14mph over only 130km hilly course in Texas Time trials. Totally different kind of riding, not as competitive, so what I would like is simply reliable and comfortable.

Thanks for any ideas.

Regards,

Tom Rodgers

[Ken Lanteigne]

Tom,

It sounds like you have significantly more wrenching experience than I, so I just have a couple comments.

For reference, our tandem was a mid 80's Santana with a triple front, upgraded to 8-speed indexed rear, using bar-con shifters.

We did 90% of our riding on the middle ring, 9% on the small, and 1% on the big ring.  Simply because the gear range of the middle ring covered 90% of the terrain/speeds we rode.  

Maybe I missed it, but I don't see where you describe your shifters.  Are you using brifters, bar-cons, or something else?  

In my experience, particularly on triples, front indexing can be problematic.  I've spent far too much time at the bike co-op where I volunteer, trying to get indexed front derailleurs to work through the gear ranges.  All it takes is a little bit of chain wear, a little bit of cable housing movement, or the derailleur being just a touch too high or not perfectly aligned, and the system won't work.

Ken

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[Tom Rodgers]

---------- Forwarded message ---------
From: Tom Rodgers <t...@svi.net>
Date: Wed, Oct 4, 2017 at 4:37 AM
Subject: Re: [LSR] Help! Tandem triple chainring shifting issues
To: <dans...@flash.net>

I think I said I was using Ultegra triple (STI shifter) for the front derailleur, both match. Rear is no problem at all. Thinking of trying 9-speed non-indexed lever (left bar end shifter) if changing derailleur and cable does not fix it. I just really need about another millimeter or two of outer movement to get it to stick to 54 ring, the feather back to put chain in middele of change.

Already moved derailleur a dozen times, but really, the Co-motion with ultegra triple just doesn't have much room for "legit-mate" movement, by that I mean without bending anything or putting the cage off angle. Sometimes these little unorthodox tricks work for a 2x front derailleur, but none of that works here. About all you can do is move the band on the tube up and down a millimeter or two, and I've tried all of that up and down. Because the three rings make a sharp angle that the derailleur must follow over a longer distance, you can't deviate. Again, the only thing that does NOT fit and work perfectly is the last millimeter of outward travel to ensure the chain "sticks" to the largest ring in that shift.

Actually, just changing to a newer FD of the same model has helped, and I have a new cable coming Thursday. Bike shops just don't stock the 3000mm cable much, at least not Bicycles, Inc. by me. It may just be a question of cable tension, since all the limit screws are where they should be.

If none of this works, I'm going to try the non-indexed bar end shifter I have left over from 9-speed in 1999--still in fine shape. Actually, I don't mind bar end shifters on aerobars for moving the FD, having trained 25,000 miles in 2005 and ridden solo RAAM without any STI shifters, only with indexing on the right aerobar. Some folks love STI and ram handlebars, but I do not. I was even thinking of moving the existing STIs onto a cowhorn bar before the shifting problems became chronic. I really NEVER use drops unless I'm racing draft-legal USAC events with sprint finishes. I like upright or aero positions 99% of the time. 

Again, trying to spend the least time and money before maybe going to electronic in 2018. Wife has shown amazing commitment to regular training on the tandem now, something I really did not expect, so now I don't mind spending money on her like I have on my six-figure triathlon bike habit of the last 19 years.

Thanks for all the help. Wanted to see how other people actually used a triple in practice. There's a good reason Shimano and SRAM have not pursued them with newer models or electronic, because it increases negative probability outcomes by 50%. I think they are moving soon to something like a 2x front with 34-52 and a rear cogset of 11-40, and I think that's where I'll eventually be. From an engineering persective, it's easier to make the RD move onto bigger and bigger cogs than it is to make a triple reliable.

Regards,

Tom Rodgers

On Tue, Oct 3, 2017 at 5:32 PM <dans...@flash.net> wrote:

Tom, I’m not much of a mechanic so I’m not much help, but thought I’d throw in a little. 

2. I stay in the middle ring 95% of the time. Only shift to the big or small on rare occasions, I can trim my Campi front derailleur so it does not rub, so no issue with big or small cogs. 

I do not think that you can shift a triple with Sram, but if you could that would be a nice deal. 

might try moving the front derailleur up ??? just a little ??

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