Maury Cohen

I have a Calfee Tetra Tetra, and the shifting has ALWAYS been less than ideal. I accepted that tis is in part due to the longer cables, etc. on a tandem leading to a bit of fuss at either the lowest gears or the highest.
After riding a recent 29'er mountain bike with 2x10 gearing it occurred to me that his gear setup might be ideal for tandem application.

Has anyone made this conversion/

If so, can you report the rough cost of the changeover?

akexpress 

We converted our Calfee Tetra to 2x10 Ultegra DI2. As the prices for Di2 have come down significantly the difference in mechanical is getting small. To have a decent wide range you will need a long cage rear derailleur and a wide range cassette. We run 11-36 with a 50/34 compact and are very satisfied. The shifting is better then our D/A mechanical singles. There are a few other threads regarding 2x10.

rmac

How does the Ultegra Di2 work with a 11-36 cassette? I thought the maximum teeth it can handle is 28.

zonatandem

Instead of technically having 27 gears you'll be down to 20 gears.
As long as your high and low gear ratios are the way you want 'em, it'll work fine.
Switched from 3x9 (with barcons) to 2x10 (with Di-2) for testing purposes of a new battery systems.
Di-2 worked great for about 1,600 miles, then went to hell.
For sake of dependability went back to 3x9 with barcons.

akexpress 

the rear derailleur is modified to accept a long cage. K-Edge does the conversion in a couple of days, they have been modifying them for a long time, both Dura/ace and Ultegra. There are quite a few of us on this forum with the modification.

2frmMI

K-Edge website:
https://www.ki2bike.com
Bikerumor news post about K-Edge mod:
k-edge-ki2-kit-converts-di2-to-mountain-bike-group

rmac

Thanks everyone. So it's about $500 if you send them your dérailleur?

akexpress 

no it is down to less then $200 if you send them the derailleur or you can buy a new modified one direct from them. Talk to Joe Savola at K-edge for the conversion.

bikeinxs

11 speed ultegra Di2 will officially support 32 teeth on the back this fall. 2x11 is starting to look pretty viable for most situations.

https://velonews.competitor.com/2013/...-brakes_292856

diabloridr

Obviously there is no such thing a free lunch.

With fewer gears, the jumps will be larger if the high and low do not change.

This can be a deal breaker, especially for tandems where most teams already compromise their cadence.

As a related data point, beloved stoker had a triple on her old single, but wanted to go to a double when we built up a new bike for her. Opted to use the SRAM WiFli approach (11-32 10 spd cassette paired with 52/36 chainrings).

Bad news is she never did get used to the wider jumps.

Good news is we swapped her over to a 11-28 cassette and eliminated the issue with the big jumps and she is satisfied with the range.

rmac

Hmm. Here is what they said:

"Generally, we have our customers ship their derailleurs to us where we
retrofit them with longer cages and then ship back. This process usually
takes about a week with shipping time included. ... The MSRP on this retrofit is $335."

DubT

Our Tetra with 3X10 shifts very well. What is the issue and which gears do you have trouble with?

Wayne

Maury Cohen

I've adjusted the front derailleur several times and it either drags in the low low or the high high combo. Can't get it to work smoothly at both ends.

waynesulak

I have heard that Shimano made a considerable improvement in STI triple when they went from 9 to 10 speed. I have never tried to adjust a Shimano 9 speed triple but the 10 speed triple can easily be adjusted to work with no FD dragging.

If you were to convert to Shimano 10 speed triple, the 9 speed rear derailleur will work fine. Cost would still be cassette, chain, shifters, FD and possibly front rings. Depending on the existing wear on components you might be ready to replace the cassette, chain and front rings anyway which would leave the shifters and FD.

PMK

Before making the jump and expecting the same performance, ask yourself what was the shifter, der and gearset on the off-road tandem. We run 3x9 SRAM XO on both our off-road and road tandem. We don't run drop bars on road, that's just our preference. Shifting is very solid, like a truck. Maybe road setups can deliver this, just not sure. If it works well off-road, the same works even better on-road, not accounting for ergos.

PK

akexpress 

I totally agree with Paul. We have two full suspension mtn tandems with Sram grip shift triples and they shift with authority and inspire confidence. Even more amazing is they do it caked in dirt and mud, wet or dry. Our DI2 is the only setup so far that is as good on the road tandem. If you really want to start a lively discussion, talk about the difference in the cost between the best high end mtn tandem ( full suspension, couplers,carbon bars,powerful brakes etc) vs high end road tandem. Less than 1/2 the cost for the mtn tandem.