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OT: Shimano Alfine 11 Di2 SEIS and backwards compatibility with existing hubs

October 17th, 2012 by

This post is completely OT for openSUSE, but I don’t have a better place to put it to share this useful snippet of information.

Shimano has just released its electronic shifting system for Alfine internally geared hubs. In mechanical Alfine, the gear cable pull is translated into rotation and gear selection by a detachable unit that sits on the end of the hub.  Alfine Di2 SEIS replaces this with a MU-S705 motor unit controlled by an electronic brake lever.  But it also introduces a new hub (SG-S705).  I wondered whether the motor unit can be retrofitted to existing hubs, as I have the original Alfine 11 (SG-S700) on my Genesis Day One, and I’m not completely happy with the Versa drop bar brake lever integrated shifter*.

So I mailed Paul Lange, Shimano’s German distributor, to ask. The answer I got is that the SG-S700 hub can not be used with the Di2 components, because it has a return spring for upshifts, whereas SG-S705 does not since the gear selection in both directions is actively performed by the motor.  If you put a MU-S705 motor unit on an SG-S700 it would be working against the return spring.

As far as I understood it, there is a spring in the SM-S700 cable end unit – I didn’t know there is also one in the hub itself, but I’ll check next time I have the wheel out.  Until then, my dreams of perfect drop bar shifting are just that, because at 400 quid SRP the hub is a big investment.  Maybe Shimano will take pity on me and make a mechanical STI…

* Mostly because there is no little cam decoupling the upshift lever from the cable spool inside the Versa shifter, so sometimes it shifts up several gears at once.

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2 Responses to “OT: Shimano Alfine 11 Di2 SEIS and backwards compatibility with existing hubs”

  1. Shimano guy is quite right – there is a strong return spring in the hub. I suspect there’s more to it than that, too. The cassette joint doesn’t have a spring.

    I too suffer the Versa shifter. It’s a pain. I’ll be going Di2.

    Cheers

    Bob

  2. Fabrice

    Any news on that issue ?
    Me too, I have an SG-S700 hub, and would really like to be able to convert it to Di2.