Through our 37+ years of tandeming we've tested several new tandems and tandem related products.
Well, at ages 80/77 we're test dummies again!
Bob Davis, of Zona Engineering and Development in Peoria, AZ made us an offer we could not refuse!
Would we like to test ride the Dura Ace Di-2 electronic shifting system with a new type of battery set up?
We were using the old reliable barcon shifting method for the last 30,000-some miles after having disposed ot the D/A STI that we had some issues with.
Bob would modify our tandem and install the system at minimal cost to us. In return we had to supply feedback and voltage readings before/after each tandem ride.
Not really being into electronics, we had some questions.
We would loose our triple chainring set-up that we liked. Di-2 only accepts 2 chainrings so we switched to 48/32 ring combo; swapped our 9-speed for a 10 speed cassette (11/34) and of course had to install a new 10-speed chain.
This allowed us to keep about the same gear range we had before. Old setup's top gear was 130 inches (which at our ages we hardly used any more) and the new arrangement tops out at about 118 gear inches. Granny gear remained in mid-20s range
So, we switched from 3x9 speed combo to a 2x10 setup with satisfactory gears for us.
To be sure the change from barcons to electronic shifting is enlightening!
While at first glance the Di-2 carbon fiber shift/brake levers look a bit like STI, they decidely operate differently.
A subtle touch of the hi/lo buttons on the brake levers and the shifting is done.
Instantaneous . . . and front derailleur aligns the chain automatically with whatever cog you shift to.
The 48/34 combo or 32/11 combo? Works . . . noiselessly.
Bob routed the electronics cables from shift/brake levers under handlebar tape and then internally through lateral tube. Wires exited at rear of stoker's bottom bracket and chainstays. Routed the rear derailleur electronic cable unde chainstay and the other cable to the front derailleur.
We have about a hundred miles on the system.
So far so good . . . we are impressed!
Currently testing a Nickel Metal Hydride (NMH) Low Self-Discharge (LSD) batttery for the shifting.
Shimano utilizes a Lithium Ion rechargeable battery ususally located near the bottom bracket on the seattube.
Craig Calfee offers a battery that fits inside stoker's seatpost.
Bob Davis of Zona Engineering has expanded that by making it possible to recharge the NMH battery without seatpost removal.
Of course, we did not have Di-2 shifting on our Zona tandem, so Davis had to modify it a bit.
The electronics cables run under the handlebar tape from the shift/brake levers into the lateral (internally) and exitnear the back of the rear bottom bracket/chainstay juncture. Then externally to the front derailleur and under the chainstay to rear derailleur. A very clean looking setup.
A small connector exits the stoker's seatpost under the saddle for recharging.
Another connector under stoker's saddle allows for voltage readings to be taken during our test period.
The original price for D/A electronic shifting of about $3,500 was a bit much for most of us; introduction of the Ultegra version at about $1,300 less will have more folks consider the electronic shift option. The Ultegra is a tad bulkier looking and about 6 ounces heavier but seemingly works as well as the Dua Ace version.
As more units are sold, and other component manufacturers enter the fray, we can see these systems proliferate in the future.
Pedal on TWOgether!
Rudy and Kay/zonatandem