RichardT

Hi all

Well, my tandem crankset search almost worked out.
Next step, a group
I'm sure there is already a topic about Di2 on this forum but I couldn't find it yet, not the information I needed.

Does anyone of you have experience with Di2 Ultegra or DA?
I'm looking around for a set for my tandem.
In Europe those are hard to find for a tandem.
What's a good address in the USA for a complete set for a tandem with, if possible, the battery mounted on the left bottom rear fork

Of course it has to work as well, the set on a tandem so I'm curious about all the experiences....

Richard

Chris_W

The thread with the most info on this topic is here: Anybody use Di2 on a tandem?

zonatandem

Did some testing with Shimano Dura Ace Di-2. Minimal cost to us as test-dummies.
Utilized an in-the-seatpost Nickle Metal Hydride (not the Shimano Ion) battery.
Had to recharge at about 1,400+ miles. All worked great. Loved the self-adjusting front der. for chainline. Loved the crisp/instantaneous shifting.
However, 300+ miles later developed severe issues with front der. Would not shift/would overshift/could not adjust. Ended up having to dismount and walk up a 6% grade.
Battery became cantankerous; found loose battery connection. But did not solve the front der. issue. Apparently the adjusting screw for front der. had no threads to go into! According to a knowledgeable mechanic there's a plastic insert that would allow the screw to thread in.
Battery indicators never showed warning light to re-charge; instead front der. quit working . . . another indicator to recharge.
Seems they system has some teething problems!
Switched back to old fashioned/reliable 9-speed barcons and triple chainring.
Just our input/experience.

akexpress 

We have ultegra Di2 on our coupled Calfee. We don't have a huge number of miles on it yet but so far it is great. It is the best shifting we have ever had including our singles. Our setup is lightning cranks with compact 50/34 gearing and we run a11/36 xt cassette. We have the K edge rear derailleur modification. This gives the same low range as we had on our Ulterga triple cranks and we lost a little high gears with the 50 vs a 52. We are able to use the entire cassette on the large chainring and all but the smallest two cogs on the small chainring. So far we have not felt the slightly larger gaps between shifts. We are able to climb sustained 5 % grades in the large chainring and have not needed a lot of double shifts. We are presently in route to a Santana trip to New Zealand and will have a better perspective following this trip as there will be plenty of climbing. Our bike was returned to Calfee to internalize all the wiring which they did a beautiful job. We have to connect one wire junction at the coupler when we assemble the bike. All the other connections were nicely shrink wrapped and siliconed in place inside the frame. The bike now has only the rear brake cable running to the disc and it has a very clean look. Calfee utilized their seat post battery in a Thompson masterpiece seat post. As we travel often I have a spare battery and a stock Shimano battery that can be connected to a front shifter and taped under the stem for complete redundancy if needed. With lightning cranks we can always change to conventional gearing or triple, also Praxis makes some mid gear chain rings 52/36 that might work well depending on the terrain and team strength. We use a belt drive for timing. We committed all the way and had the cable stops for mechanical removed.

twocicle

akexpress, photos please

and did you ever find any solution for doing same-side gates belt drive (130bcd rings) with a compact drive ring setup?

RichardT

thanks, all, for the info.
Positive and negative......
But, can anyone tell me where to find a set for a tandem for a reasonable price?

waynesulak

That is a good one!
I know I know it is all relative.....

twocicle

Reasonable as in the eye of the captain or the pocketbook of the stoker?

This used Calfee Tetra for sale w/Di2 has to be near a record price point. Zipp wheels ($4k) and Lightning cranks $1700+) tally up.

Open Lateral

We had Di2 on a tandem, and it works great, but when electronic pushes you to a double front, it opens up all the rest. I like SRAM Red much better, just my opinion. Something about pushing a button is not shifting to me, and the shift is 100-200ms sooner, so the timing is slightly off from what you are used to.
I never understood Shimano with their limited options on electronic since the shifter options open up once you go electric with the shifting. At the time, there was NO marketing of the ability to shift from the clipons as well. They now have cable extensions for the longer boom tube run.

Maggie Rose

I don't understand; Shimano mechanical and especially Di2 shift better than SRAM in the front ring. And SRAM Red is also "pushes you to a double front". Are you stating that you prefer SRAM because of the ability to run a wider range rear cassette? Ask yourself you many triple riders would pony up $ for electronic shifting and you have your answer as to why it's not available in a triple.

Turbotandem

our bike pictured below.
Dura ace 2013 di2, yumya long cage adaptor including long b tension screw, right side belt V2r paketa, lightning compact crank praxis 36-52 110bcd with proprietary paketa coupling to 130bcd gates. This is the first pre-production adaptor from Paketa and I am currently the only one riding it. By next year I'll no longer be cutting edge... Interanl wire harness by Bob Davis, calfee seat post battery in captain's seat post. 11-36 SRAM XX casette.

I thought I would miss the "tight" gear changes of our prior "ordinary" configuration, but to the contrary. And I was one of those riders in love with the granny. We have 36 chainring-36 cog 1:1 gearing, and can go lower if we like to 34-36. To get a comperable ration on a triple means mating an 11-32 casette with 32t granny, or even a 11-28 with a 28t granny. The most disruptive hurdle in our riding prior to this bike, was dropping into the granny. I hated that shift and dreaded doing it, dropping the chain and just having to nearly stop pedaling to make the shift. We ran an 11-32 with 32t granny when we had a granny. So no with the 2x10 set up, as most of the high end mountain bike industry has adopted, the difference btwn the 11-32 and 11-36 casette is almost all on the lowest couple gears where the degree of changes btwn gears really don't mater. On the high end I think there is 1 or 2 tooth difference btwn the 11-32 and the 11-36 we ride. Accepting that is easy compared to the gains in shift quality and getting ride of the dreaded granny drops. I suspect teams trying a 2x10 setup would not go back.

We ride the rockies, 350,000 feet of climbing in 2012, but we are a light team at 290# and are drawn to race endurance events. Larger teams or touring teams I can appreciate need the triple.

Also intersting to note that the right side belt prohibits the chain from droppinng below the inner ring. So if you wanted you could put on a 34t-53t or even wider spread. I don't have the need to pedal hard down hill, so 52t works well for us.

waynesulak

I see you mention difficulty getting into the granny. We had the same problem when using 2006 Ultegra. We got pretty good at pausing together in order to make that shift but uphill a pause is a bad thing. Switched to Campy shifters and now we shift from middle to granny or big to middle under full power. I usually still call that shift due to the sudden increase in cadence as it drops onto the granny. Pausing to shift to granny is a Shimano problem we no longer have.

With a 12-25 rear cassette our cadence range can stay between 90-100 where we like it. Bigger gaps require a larger cadence range. That is a tradeoff we don't want to make. We are also 290 lbs and could easily use a double with a mountain cassette but with front shifting under load up or down we don't see the need to live with bigger cadence changes.

I am considering Ultegra electronic rear shifting with Campy triple front but not sure I want to live with the mismatched shifters and another battery to worry about.

Turbotandem

we had campy chorus front der. when we had a granny. I still had to bend the cage to get it to shift. The tandem had oversized stoker seat tube, so the der. touched the frame and went no further, so the cage needed one more mm.
On the 2x10 setup the top five or six cogs in the 11-36 set are plenty tight and accomodate +-10% shifts when we are in that power zone. When we use the tallest section of the casette we are gennerally in our lower climbing cadence of 80-95.
IMHO the difference in cadence a very sublte distintion in a discussion on how well Di2 works on a tandem. For me, I am SOOO tired of constantly trimming the front der. Even before getting the Di2 I was getting sick of that. Now on our tandems with manual der.s. I actually have our cyclecross climging tandem set up as 1x10 with right side drive and love that too. With the Di2, we can shift while standing in a climb, the shifts are flawless, the front der auto-trims, and I have no call-outs or pausing to shift into a granny. And the only compromise I have to accept a cadance falling from 100 to 89. Here's the gearing:
https://www.gear-calculator.com/#KB=3...UF=2111&SL=2.1
I'll take that upgrade.

reburns

We have a 2005 Trek T2000 with Ultegra FD. I also used to treat drops to the granny very cautiously while climbing. A few months ago I decided to install a chain catcher by N-gear called the jump stop, even though I almost never had a problem with the chain coming off of the inside of the small ring. Probably installed it more out of not having enough to fool with than anything else. Anyway, the instructions that came with the jump stop suggested that with the catcher installed it was now possible to adjust the FD low stop to the inside limit, facilitating quicker middle-to-small ring shifts. I did this and the drops to the granny while climbing are very quick and easy now. With that one improvement, I now have zero complaints with any shifts on this bike, it just always works quickly and precisely.

Turbotandem

I was thinking about your 12-25 casette today. That's tight. What do you have for chain rings?

Turbotandem

we've used a third eye chain catchers by a few makers. They don't always work for us when the china drops forward of the catcher. I used to be a staunch granny advocate, but no more after riding our current configuration. Maybe it takes riding it to say, and it's not for everyone. The pro's out weight the cons, and until there is a triple Di2 I'm sharing my experience that it the Di2 is worth it, with little if any loss on the "con" side.

Hey, shout out to Ritterview for his advocacy of Praxis Rings. We made that upgrade and I love them. The up shift from 36 to 52t is so smooth.

waynesulak

I like a tight cassette. We used to run stock 54/42/30 rings that came with our Speedster. My stoker wanted shorter crank arms so I took that opportunity to switch to 53/39/26. Now that my stoker can pedal up to about 108 cadence that adds to the top end speed and we found we really like a 50/36/24 front setup. We like to use all of our limited power and when on the edge having just the right gear is important. We spin out in the low 30s mph but that only happens down hill and we actually gain speed by going into a tuck. We just don't have the power to push air above that speed on the flat.

Below is a gear chart:


.........24..... 36 ....50
[TABLE="width: 151"]
[TR]
[TD]25[/TD]
[TD]0.96[/TD]
[TD]1.44[/TD]
[TD]2.00[/TD]
[/TR]
[TR]
[TD]23[/TD]
[TD]1.04[/TD]
[TD]1.57[/TD]
[TD]2.17[/TD]
[/TR]
[TR]
[TD]21[/TD]
[TD]1.14[/TD]
[TD]1.71[/TD]
[TD]2.38[/TD]
[/TR]
[TR]
[TD]19[/TD]
[TD]1.26[/TD]
[TD]1.89[/TD]
[TD]2.63[/TD]
[/TR]
[TR]
[TD]17[/TD]
[TD]1.41[/TD]
[TD]2.12[/TD]
[TD]2.94[/TD]
[/TR]
[TR]
[TD]16[/TD]
[TD]1.50[/TD]
[TD]2.25[/TD]
[TD]3.13[/TD]
[/TR]
[TR]
[TD]15[/TD]
[TD]1.60[/TD]
[TD]2.40[/TD]
[TD]3.33[/TD]
[/TR]
[TR]
[TD]14[/TD]
[TD]1.71[/TD]
[TD]2.57[/TD]
[TD]3.57[/TD]
[/TR]
[TR]
[TD]13[/TD]
[TD]1.85[/TD]
[TD]2.77[/TD]
[TD]3.85[/TD]
[/TR]
[TR]
[TD]12[/TD]
[TD]2.00[/TD]
[TD]3.00[/TD]
[TD]4.17[/TD]
[/TR]
[/TABLE]

That is a change from .96 to 4.17 or 434% with the biggest jump under 12%.


We sometimes use a 12-28 cassette which gives a wider range of 484% with the biggest jump of 13.3%. We do notice that 13.3% jump but is is nice to have a little lower gear sometimes. Our power to weight is not the greatest.

[TABLE="width: 151"]
[TR]
[TD][/TD]
[TD]24[/TD]
[TD]36[/TD]
[TD]50[/TD]
[/TR]
[TR]
[TD]28[/TD]
[TD]0.86[/TD]
[TD]1.29[/TD]
[TD]1.79[/TD]
[/TR]
[TR]
[TD]25[/TD]
[TD]0.96[/TD]
[TD]1.44[/TD]
[TD]2.00[/TD]
[/TR]
[TR]
[TD]23[/TD]
[TD]1.04[/TD]
[TD]1.57[/TD]
[TD]2.17[/TD]
[/TR]
[TR]
[TD]21[/TD]
[TD]1.14[/TD]
[TD]1.71[/TD]
[TD]2.38[/TD]
[/TR]
[TR]
[TD]19[/TD]
[TD]1.26[/TD]
[TD]1.89[/TD]
[TD]2.63[/TD]
[/TR]
[TR]
[TD]17[/TD]
[TD]1.41[/TD]
[TD]2.12[/TD]
[TD]2.94[/TD]
[/TR]
[TR]
[TD]15[/TD]
[TD]1.60[/TD]
[TD]2.40[/TD]
[TD]3.33[/TD]
[/TR]
[TR]
[TD]14[/TD]
[TD]1.71[/TD]
[TD]2.57[/TD]
[TD]3.57
[/TD]
[/TR]
[TR]
[TD]13[/TD]
[TD]1.85[/TD]
[TD]2.77[/TD]
[TD]3.85
[/TD]
[/TR]
[TR]
[TD]12[/TD]
[TD]2.00[/TD]
[TD]3.00[/TD]
[TD]4.17
[/TD]
[/TR]
[/TABLE]


For us the triple allows us to have our cake and eat it too. Tight gears to use when at threshold and low gears when climbing. Since the front shifts well we like it. If we had problems shifting the front we might do something different. Gears are about as personal as saddles. The choice depends on terrain, riding style, power, and ride goals.

Turbotandem

Thanks for the detail, this will help the forum compare. We cover about the same 473% range. F

or a low gear, the max development on a 2x10 compact configuration is 24" while on yours you have a skoch more at 23". Probably could be deeper if the smallest chain ring can go smaller.

Your deepest single gear change represents a change in cadence as you shift up from 105 to 92 with a more typical candence change in your configuration of 105 to 95. Our configuration single deepest change represents a change in cadence as I shift up from 105 to 89 with our more typical cadance change in our configuration of 105 to 93. How does the forum judge that comparison? Splitting hairs or functionally disparate.

Both your and mine deepest change is actually droping into the small chain ring. Yours 50% change from 36 to 24, or a change from a climbing cadence of 80 to 120. Mine similarly 45% dropping from 52 to 36. The neat thing about the Di2 is that change can be done with an instant upshift on the cog with the push button. One left click, two right clicks, under a second later and my stoker does not know we've made that shift. I can not pull that off on our manual tandems.

Ritterview

The Third Eye and very similar Dog Fang have to be just so, and if they slip the slightest bit, the chain slips underneath it, and the captain might tend to utter uncharacteristic expletives.



In my experience, the N-Gear Jump Stop is the bomb. It's placement is more stable, and even with our 5.5 mm 11-speed chain it is nigh impervious to the chain slipping underneath it. It better gets the chain back on the ring, so that after momentary drama, the chain will re-engage, and you are back going before anyone around you can comment derisively.


Front of Jump Stop on Calfee triple

Rear of Jump Stop

On USPSPro's Calfee, they had a fender boss installed, which they use instead of the N-Stop tube clamp. The N-Stop blade is thus bolted directly to the seat tube. If ever my Calfee takes another trip to Calfee HQ, I'm going to get one of those fender bosses installed.

Here is a pic of a Calfee water bottle boss, the fender boss is the same thing, only on the opposite side of the seat tube and very low.




We went through a chain drop dark ages, when our stoker's Lightning crank unbeknownst to me had about 1-2 mm lateral play. The chain would drop repeatedly, and at times become lodged between the triple chainring and seat tube. This play would defeat the chaincatcher. Oh, it was terrible. Shims from Lightning cured the play, and now with an N-Stop we hardly ever drop the chain. It shifts quite well and reliably. [Back to OP -->] If I had seen Di2 as a way out of chain drop woes, I would have probably seized upon it. But the shim and Jump Stop cured the problem for $20, which is a lot cheaper than Di2.

PMK

Impressive the shifting is that good under so much load of standing while climbing shifts. Nice to be able to turn 95 rpm during a standing climb.

For us, we have folded rear cassette rings during seated climbing, no shifts involved. Probably 85 rpm, but bumpy or loose terrain off-road. Usually it's #2 or #3 and it fouls the smooth operation of the next sprocket down.

PK

Ritterview

I think gear-calculator is the ultimate way to look at and compare drivetrains. Quite germane to the OP, this is a comparison of Turbotandem's Di2 and my 11-speed triple (actually, I don't have a 28t granny yet, that awaits the on-order Athena long-cage RD to replace my short cage insufficient chainwrap SR RD).

On top, is Turbotandem's Di2, with the rear cassette about the size of a manhole cover. This provides range that is about the same as the triple. The one-cog jumps aren't too large, they just have to be called out, lest the stoker dig her aero helmet tail into her back.

On the bottom is the 11-speed triple, with the fine tuning rheostat shifting. We find the cadence that is optimum, and I make many one-cog shifts to keep it just so. This is quite helpful in riding with a group of rapidly accelerating half-bikes on rolling terrain.

waynesulak

While Ritterview's chart does show the larger jumps in single shifts I think that it really boils down to his statement that he is able to keep the cadence "just so" with a narrow range cassette. This is the benefit to us of the third ring. While we are able to pedal comfortably between 90- & 100 cadence we put out the most sustained power in the 95-100 range. This means the ability to keep cadence "just so" gets us the last bit of power not available at 92 cadence and still have low gears when needed.

That fine tuning may not be important to you and if it is not then a triple looses some of its appeal. In that case then you can fix your front shifting issues by going to a double. Like I said above gearing is very personal so what works for my team may not be the best for someone else.

Dean V

How do you come to the conclusion that you need to keep your cadence within such a narrow range to get optimum performance? I find that it can be quite variable, for me anyway. I have also done a bit of fixie riding on the road and even though your cadence is all over the place performance only seems to really suffer at the extremes (<40,>140 rpm).

Ritterview

I think the idea is that there is an ideal cadence which is most efficient, that produces the most power, or is more sustainable over a long ride. The purpose of the drivetrain is keep the team as close to that cadence as they can.

This graph has cadence (rpm) on the X-axis,and power on the right Y. This is for short, high-intensity events, but the idea is the same.



Here is a graph of cadence vs. power for one rider in a hill climb (from an interesting discussion of cadence vs. power vs. torque). On the face of it, for this rider, the cadence between 95-100 generated the most power. Keeping to that range will be easier with a tighter cassette ratio.

waynesulak

This is an example of what happens to us:

We are going full bore tracking down a single. You probably know what it is like, heart rates pounding at maximum sustainable rate and legs are hurting. We are increasing speed - making progress and pulling him slowly back - Yeah. Time to shift to a higher gear, if the cadence drops below 95 we have trouble maintaining our existing speed, slow down and must shift back to the easier gear which allows us to repeat the process. Very frustrating. If the cadence drops below 90 in the higher hear we slow down dramatically and get dropped. If we can shift and stay at 95 then we can maintain momentum and possibly continue are acceleration. If we can't go any faster then at least we maintain speed at 95 rather than 102 or so.

This is really important to us when we are right on the edge of our strength. If we have some in reserve then sure we can hit the pedals harder and sometimes grunt the higher gear up to the comfort range. If we are going all out trying to go fast then there is no reserve available. Likewise there are only so many times I can grunt it out before the legs will no longer respond. Keeping the cadence just right saves those grunts for later use.

We are most efficient at a steady cadence. Wide changes in cadence can be great fund and are a great workout but I don't think they get the most speed out of our limited power.