Di2 hybrid question

[R3PAUL]

I am planning a MTB with Di2 build, but already have a Road bike Di2 set up so I want to keep cost to a minimum.

My question is will Di2 work with a Di2 RD and a double crankset/mechanical FD or will it just confuse the RD when mechanically shifting on the FD?

More specifically I was thinking of ordering a 10 speed XT groupset with a double crankset and fitting a Di2 rear mech, internal loom, handlebar set and a Di2 drop handle bar switch. http://www.fawkes-cycles.co.uk/19146/pr ... -hand.aspx

To keep the cost down even further I would use an 800maH Lipo stick battery and mount it in the seat post as in my road set up (9 months on and still not charged).

Is this even feasible or will I need to keep it to one chainring or take the more expensive option and add a Di2 FD?

Thanks.

[pritchet74]

I am 99% sure that you do NOT need a FD to have a Di2 RD setup. Madcow or Jeffr could confirm though.

[R3PAUL]

Thanks. I have seen Madcows MTB set ups with one chain ring on the front and a Di2 RD on the back, but I want to know if I can have a double chain ring on the front with a mechanical (Shimano XT 10 sp.) FD or is this going to confuse the Di2 RD?

So basically, on the bars I will have one mechanical shifter for the FD and one Shimano Di2 electronic sshifter for the RD. Doing it this way it keeps the cost down whilst still having the full range of gears and not just being restricted to one chainring.

If it would work and the Ultegra Di2 RD does turn out to be the same cost as normal Dura Ace, then it could turn out to be a reasonably priced set up.

[Ypsylon]

The FD won't confuse it. It's the FD that trims according to the position of the RD, the RD is just under the sprocket it's supposed to be under.

[R3PAUL]

Thanks, but just to confirm I would have NO Di2 FD. It would be a mechanical XT FD.

The set up would be as follows:

Shimano XT M785 10 speed DOUBLE chainset
Shimano XT Dyna Sys 10 Speed Front Derailleur

This would be operated by:
Shimano XT 10 speed left hand shifter.

At the rear:
Di2 Rear Derailleur

This would be operated by:
Shimano Dura Ace 7970 Di2 10-speed drop handlebar switch - right hand

To Link the Di2 components up:
A Di2 Internal wiring loom
A Di2 Handlebar Cable set

And for power:
A 7.4v Lipo Stick battery 800mAh

On a normal Di2 rig the Di2 FD shifts/trims as the Di2 RD moves across the rear cassette. Take the Di2 FD away, replace it with a mechanical one (XT 10 speed).

Would this work or would the mechanical shifting on the double chainset confuse the Di2 rear mech?

Thanks.

[Cyco]

Pricing released for Ultegra Di2 in Australia puts it about 5% under the price of mechanical Dura-Ace, at this stage.

[R3PAUL]

5%? Might as well buy normal DA Di2 if that's the only discount they are going to give. I would expect the DA Di2 price to take a nosedive once the Ultegra equivalent is released though.

This second-tier group is expected to be around half the price of the flagship Dura-Ace set

http://www.bikeradar.com/news/article/s ... look-30616



From what I can see the only differences are colour, thinner wires/plugs and aluminium levers. If it ends up being half the price of DA Di2 then I can see there being supply problems as every man and his dog will want it.