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New tandem componentry advice

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New tandem componentry advice

Old 11-05-17, 03:55 AM
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bomberesque
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New tandem componentry advice

Hi

My wife and I ride a 90s Mercian tandem. We love it but, as it's a racing tandem, the stokers cockpit is rather on the short end and it can only fit caliper brakes. For unloaded day road riding this is not an issue but for loaded touring (Burley trailer out back) it has been a problem, especially on descents where the brakes just don't provide enough power.

... plus I wanted to buy a new bike and the tandem budget was the easiest to get approved

so, I've just ordered a new tandem frame / fork from Ritchey

This leads to some novel componentry dilemmas for me. the Mercian has downtube shifters, which I run friction with a 9sp mountain cassette and a 30/40/50 triple (old TA specialities) but ofc the new frame needs more modern shifters. final gear spread is 25-127" and does what we need it to, both on the flat and in the hills except the odd steep climb with the trailer loaded

The new tandem will be drop bar for the captain so I'm looking at drivetrain options, most available tandem chainsets seem to be triple but triple drop bar shifters are not easily available, which makes some sense considering the range you get from compact double these days. Plus the chainset ...erm... sets are OMGWTF expensive and nice really wide cassettes available these days

So I was wondering about the following, I know it sounds like a bodge but bear with me
  • Set of SRAM force CX1 shifters (left is just a brake lever, right is SRAM 11sp)
  • a wide ratio 11sp rear cassette (11-46 for preference)
  • SRAM MTB rear derailleur
....So far I am confident that this is all compatible (except the capacity of the RD, which might only be 42T) Now the screwy part...
  • compact 2 ring cranksets front and rear (probably 50/34 but there are options). No special tandem cranks
  • Run the timing chain between the 2 smaller rings when unloaded on the road and between the two larger rings when offroad/ proper hills. I reckon it'd be less than a 10 minute job to swap the timing chain and drive chains over

this means running effectively 1x11 with 2 configurations. the spread in the high configuration would be 30-127" and in the low configuration 21-87". It would be a lot cheaper to build than a trad tandem set up, would lack a front derralieur and parts would be easily available as none of it is tandem specific. However, I can see the possible issues
  • just daft, both chains on the same side, are you MAD?
  • possibly the worst of both worlds, will always be lacking the gears I want when we want them
  • faff to change the timing chain over, especially during a ride. need to carry a short length of chain to make the difference
  • Potentially miss one gear on the extreme in each configuration to crosschaining

Is this just a daft idea?

or there are compact double options that I'm missing? I think Middleburn should be able to do it as an option but with the above idea I could do the whole drivetrain (incl carbon cranks, when on special) for about the same cost as the middleburn crankset(s)

Last edited by bomberesque; 11-05-17 at 04:02 AM.
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Old 11-05-17, 06:53 AM
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bwebel
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I think you'll find this to be a bit of a mess to actually implement. It's possible that the timing chains in the different configurations would need slightly different tensions and thus would need eccentric adjustment.

What about getting two single bike 110x74 triples and then running the timing chain either on the outside 110 circle, or the inside 74mm? Or get two double compact cranks and put a third ring on for the timing with extra long bolts? Either of these is fairly easily done. I think Sugino makes some decent cranks that would probably work...or have you thought about just using the Sugino XD tandem cranks for the whole build? They aren't particularly chic, but neither are they particularly expensive. If you do do the right hand timing chain in some way, you usually need extra spacers between the chainrings to make it work, which could exacerbate the chainline issues in the setup that you describe.

With regard to the shifting, we typically use a bar end shifter for the front derailleur, which I find works a lot better than the indexed front systems. If you are coming from downtube shifters, you might just go to bar ends for both front and back as well.
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Old 11-05-17, 09:25 AM
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Thanks

good point about the 2 chainrings perhaps being too close together for the chains to cross, I can mock that up on another bike and see...
...as for eccentric adjustment when moving from high to low configuration or visa versa, yes that could be true but I have eccentrics on other bikes and don't find them too much faff to adjust (a case of how often you have to do it I guess)

however, the barend shifter comment is a really intriguing one. I have used barend shifters in the past and am not soooo keen but if just for the FD (using the SRAM Force CX 11sp doubletap set for the rear shifting) then there could be a good solution there. probably end up with tandem specific crankset(s) but at least I would get drop bar shifting for the most part with only a minor inconvenience when I want to shift the FD and it would easily accommodate the triple if I ended up with that

Just been told by my supplier that Middleburn tandem cranks are indeed available with just about any combo of chainrings (including compact double standards) and they look great, especially on a steel frame so there's that possibility if I drop some cash

Thanks for your time, New Bike Day incoming!
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Old 11-05-17, 12:00 PM
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The middle stoker crank on our triplet needs about 3mm of a spacer to have the two timing chains clear each other. You didn't indicate what the rear spacing is on the tandem. If it is 145mm, then I'd think you'll end up having to move the big ring out a fair amount, both to make the timing chains work and also to give you space to access the smaller cogs from the little ring. If you are using a regular single road bike crank, the drive chainline is 7.5 mm off with the 145mm spacing to start with.

I have 3 tandems and a triplet setup with the SRAM doubletap rear shifting and barend for the front. Pretty much the only way I figured out to use SRAM with a triple and much easier to set up that fiddling with SRAM's lousy indexed front shifting. I actually put the front shifter on the right side and do all my shifting with the right hand.
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Old 11-05-17, 11:38 PM
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We are just waiting for our frame to come back from the painter to do a similar thing.
We are installing SRAM etap with a Wolftooth Roadlink and 50-34 and 11-42 to replace the Ultegra triple that we were using. The low gears will be about the same and we will lose gears at the high end though. I managed to coast down a hill on the weekend at just under 90km/hr on my half bike so I'm not to worried about the high gears.
We're using Da Vinci cranks and the only thing I haven't worked out ordered is the new BB for the rear.
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Old 11-06-17, 11:07 AM
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The proposed setup isn't too crazy, except for the 1X bit that involves swapping timing chains. My tandem is pretty similar to your proposed option: SRAM 2x10 bar end shifters, SRAM Rival Yaw FD, SRAM XO long cage rear derailleur, 52/34 chainrings, 11-42 10-speed cassette, RIGHT side timing chain outside the big ring, SRAM Rival cranks with some tweaks to the rear crankset.

Our rear crankset has a slightly narrower chainline than typical tandem cranks to achieve a narrow Q-factor. It's like 52T 1X drive train with a 34t bailout chainring. With the chain in the 34t chainring, only the largest ~5 cogs are usuable due to interference with the shift pins on the 52t chainring. I have no complaints about the functionality of it.

As it applies to your options, any left bar end shifter should be able to shift a triple front derailleur. 42t cassette is the largest a 2x10 XO rear derailleur can handle. The rear derailleurs for 1x drivetrains can fit larger cogs, but don't play nicely with front shifting.

Here are some thoughts and options for double right side drive using single cranks:
Sync chains on the inner-most ring are tricky because the sync chain sits closer to the chainstays than a normal setup. If possible, test fit before investing lots of money into that approach. I have a feeling it won't work on the Ritchey Double Switchback due to the wide tire clearance of that frame.
Sync chains on the outer-most ring require some clearance between the big ring and the chainring such that the chains don't come in contact. If they do contact, it's ugly. If you overshift the drive chain into the sync chain, it's really ugly. It's really important to use a good front derailleur and keep it tuned. A nice set of drive chainrings would be smart, too.
These options assume the other crankset is normal road double.
Single-bike triple for captain; use the inner or outer ring for sync. Shifting should be great in all the gear combos. Watch for interference between stoker crank and chain. Use spacers to separate the sync ring from other chainrings a little bit.
Single-bike triple for stoker, with 10mm longer BB; use inner or outer ring for sync with additional spacers to keep chains clear.
Single-bike double for stoker with 15mm longer BB; use extra long chain ring bolts or a triplizer chainring to attach the third ring. Plenty of square taper options exist. No 24mm options that I'm aware of. It can be made to work with Cannondale BB30 cranks or SRAM S350/Rival/Force BB30 right cranks, FSA Omega/Gossamer BB30 left cranks, and Stages spindles. There might even be a workable carbon option with SRAM Red and FSA SL-K crankarms from the right model years.
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Old 11-07-17, 12:21 PM
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???KISS??? FWIW the capacities of both FD and RD are fudgeable. On paper, our 105 FD and RD should NOT shift a 53/39/24 and 12 - 27 9sp but it does. We were doing this in 2004, long before megarange cassettes existed for road hubs. In 2017 with the o.p.'s kind of riding in mind we would use the same triple up front, paired with an 11-32/36 10sp and call it very good. I have DT shifters on the Raleigh Coupe, Dura Ace indexed rear. Finding brifters that will shift a triple is probably not all that easy but they exist, I know Microshift/Nashbar makes them, but the o.p. is clearly a 'road less traveled' kind of guy so why not bar ends? <shrug>
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Old 11-07-17, 05:58 PM
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Barend shifters last a lot longer than the electronic stuff! They are also le$$ pricey and more reliable.
Currently have 45,000+ miles on my old 9 speed barcons on our custom c/f Zona tandem
Rudy and Kay/zonatandem
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Old 11-08-17, 08:12 AM
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WRT 3x brifters, there are still Tiagra 4603, Tiagra 4703 and 105 5703 on the market. I've been running the older Tiagra 4503 for several years on a half bike with great results (Tiagra 4500 derailleurs, 52/39/24 with 9 speed 14-28 cassette). I just ordered Tiagra 4603 for my Arriva upgrade and expect they'll work fine too.

Now 1x on a road tandem? I can't imagine giving up my triple on any of my bikes (except my MTB).
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Old 11-17-17, 12:45 PM
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Any idea what the Ritchey frame and fork weigh? How do the Ritchey couplers compare to the typical S&S?
Thanks.
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Old 11-19-17, 11:21 AM
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Originally Posted by Leisesturm
???KISS??? FWIW the capacities of both FD and RD are fudgeable. On paper, our 105 FD and RD should NOT shift a 53/39/24 and 12 - 27 9sp but it does. We were doing this in 2004, long before megarange cassettes existed for road hubs. In 2017 with the o.p.'s kind of riding in mind we would use the same triple up front, paired with an 11-32/36 10sp and call it very good. I have DT shifters on the Raleigh Coupe, Dura Ace indexed rear. Finding brifters that will shift a triple is probably not all that easy but they exist, I know Microshift/Nashbar makes them, but the o.p. is clearly a 'road less traveled' kind of guy so why not bar ends? <shrug>
The "why not" is that one can't shift them out of the saddle. OTOH one can't shift the front out of the saddle anyway, so bar end in front makes good sense. My fall-back would be a pair of brifters, with the left not connected, using a bar-end on that side for shifting the front.
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