I have a pair of Shimano 105 levers and would like to know what sort of mechanism is inside the shifter to track what gear it's on?

enter image description here

Is it a potentiometer? Or maybe small switches?

Also, does anyone know the pin-out of the 4-pin cable that connects the shifter to the Shimano's computer?

  • Shimano have applied the 105 label to many products over the years. You seem to be talking about an electric shifter. Could you be more specific about the product and year?
    – andy256
    Commented Jun 8, 2015 at 0:07
  • is the same as those ones.link Is not any Di2 or such. they have the gear sensor for the flight desk or whatever is the name of shimanos computer. I tested with multimeter and the resistance of the right level change between pin 1 and 3. so I assume it has a potentiometer. but is not the same case for the left lever.
    – TAs
    Commented Jun 8, 2015 at 7:43
  • You might search for patent applications for the design. It would likely be explained there.
    – dlu
    Commented Aug 20, 2015 at 13:42
  • @TAs check if it's a switch as it for the front derailleur. Also the pictures looks really like a mechanical one :O
    – Nhân Lê
    Commented Aug 21, 2015 at 17:01
  • Googling I found the manual and there is a 4 pin cable. NFI beyond that... instructions are ugly, screen shot in as "answer" just so you can see it.
    – Móż
    Commented Oct 25, 2015 at 6:56

2 Answers 2


Here's a screenshot of part of the instructions (Shimano pdf) that appear to match your levers.

enter image description here

You're right, there is a 4 pin cable in there, but I have no idea where you'd find out what the pins do. I strongly suspect it's a classic +power, +signal, -signal, -power layout but whether it's analogue or digital I don't know (it might just be a potentiometer). You would need to take it apart yourself and have a look, sorry.

  • 2
    Sorry for waking up such an old thread but I managed to use them with my DIY electronic shifters :) For your information its a potentiometer inside there...
    – TAs
    Commented Apr 21, 2016 at 21:49

search about shimano flight deck!

  • 4
    Thank you and welcome to the site. That was mentioned in a comment in 2015, but could do with a write-up, to say what flight deck is, when it was released, and so on. OP wants to know about the pinout of the shifters, so mentioning the different revisions could be important to OP, presuming they're still working on it after 8 years. You can do this with the edit link.
    – Criggie
    Commented Mar 17, 2022 at 5:08

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