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View Full Version : SA 3-Speed trigger mechanism OK to operate front derailluer mech?



DannyC
07-02-2014, 05:24 AM
Hi Folks,

I was wondering if an old SA 3-Speed trigger could be used as a selector for a front derailleur?
I'm asking because I have run out of room as both my grips have rotary selectors on them for the SA CS-RF hub which provides 3 x 8 speeds.
I'm interested because while I can manually change over on the front to the smallest chainwheel (and it is great for hills) on the flat it would be nice to be able to move up to a larger chainwheel.

I can always just try it I suppose and hope it works.

If anyone knows that it is a "dead-cert" and can let me know, I would be grateful.

Ta!

Neil B
07-02-2014, 08:25 AM
Hi Danny

I doubt it. It all depends on the amount of cable pull, and whether it will index in the right place.
I know you can't use a road front shifter with a MTB crank without some faffing around. An old thumbie shifter, it would take up a similar amount of room on your handlebars, or a bar end shifter might work though.

Neil

Twinkle
07-02-2014, 10:55 AM
Hi Danny

I am afraid to say it's going to fail .:taz:

The amount of cable "shifted " on a 3 speed is different 1st- 2nd and 2nd to 3rd and it was not designed for a front mech ,
There are several cheapo shimano front mech shifters available that will as Neil says take the same amount of space as a SA trigger .

regards emma

DannyC
07-02-2014, 11:33 AM
Thanks Folks,

I had (sort of) thought that that might be the case, I just have an SA 3Spd shifter in my box of bits.
I will go look for an appropriate shifter.

sandman
07-02-2014, 01:00 PM
I am going to disagree with Emma :surprised: and say "Yes" all you need is an amplifier arm at the correct angle and spacing to allow for rotary to linear lost motion between the mech and the shifter and you will get the required result
regards
John
PS Hows the LPG problem doing ?

Twinkle
07-02-2014, 01:12 PM
I am going to disagree with Emma :surprised: and say "Yes" all you need is an amplifier arm at the correct angle and spacing to allow for rotary to linear lost motion between the mech and the shifter and you will get the required result
regards
John
PS Hows the LPG problem doing ?

Well John put that way.
Yes
Anything can be made to work the correct angle will counteract the non linear pull and the arm length will correct the pull per change index amount , But that is an awful amount of fluffing about just to use a SA trigger .

regards ( up to my neck in camping gear )

emma

DannyC
07-02-2014, 01:48 PM
Hi John,

Yes an "Amplifier arm" would do the job, but it's possibly more aggro than it is worth (if simple suitable triggers are readily available), I was asking just because I have an SA 3-Spd to hand.

The LPG is basically screwed. According to the LPG guys it looks like it needs 2 new Lambda Sensors (£70+ each) + fitting.
My local LandRover garage are going to take it in next Weds to test the Lambda's and (if necessary) order new ones and fit them the next day.
If they are not the problem, then I will have to run on Petrol until I can get a better diagnosis.