SRAM SX4 Front Derailleur Trigger Issue

huggy_bizzle · April 2017

A friend of mine has given me an SRAM SX4 Front Derailleur Trigger to fit my girlfriends Carrera Vengeance as her SRAM S4 trigger clamp broke from a crash. (she is ok by the way) When i shift up to the large chainring and attempt to shift back to the middle chainring of a triple chainset, for some reason unkown to me, with 1 click, the front derailleur drops from the large chainring, straight down to the small chainring, of course sending the chain with it. This trigger has numbers to tell you what gear you are in and it physically drops from 3 to 1 with 1 press of the trigger. I guess the shifter is about 6-7 years old. Is this something that can be fixed or should I just buy another one? The set up is 3x8 and I think I can source a new trigger from ebay.

Any help would be greatly appreciated.

mattyfez · April 2017

If you are sure it's not a cable tension issue, A new one is about £10 - £12.

I suppose it wont hurt to crack open the one you have and see if you can do anything with it.

JGTR · April 2017

Have you set it up properly? High and low screw, clearances, cable tension etc?

Check out Parktools for all you need to know.

Could be wrong shifter though, I don't know if all shifters are compatible?

mattyfez · April 2017

Does it have 3 distinct clicks, and does the indicator move properly with no cable tension?

I think all the x4 left hand triggers are 3 speed

huggy_bizzle · April 2017

Thanks guys for replying to me,

@ mattyfez: I'm pretty sure it's not a cable tension issue, although I will double check this tomorrow, I know the trigger is not too expensive to replace, so if I don't get it sorted soon, I will get a new one. I have heard online that these triggers can be like a 'jack in the box' if you open them up, I may do this if I can't find a solution, but not before I purchase a replacement first, just in case. It does have 3 distinctive clicks and the indicator moves fine without cable tension and like I said, it moves up the chainrings fine, but not down. It used to, but has got progressively worse and now it's to the point that it just moves from 3 to 1 every time.

@JGTR: I believe it's all set up correctly, the high and low screws have been set up correctly, clearances and cable tension seems fine, although like I said to mattyfez, I will check again tomorrow. I have recently replaced gear cable and housing.

I do know that the trigger came from a hybrid bike that used to run on a double chainset. The right hand trigger works perfectly fine though. I'll check gear tension tomorrow and get back to you guys.

Thanks again

The Rookie · April 2017

It sounds like some crud in the detents or ratchet, it doesn't sound like a cable issue at all.

As noted, don't open it unless you are throwing it away anyway.

Blasting inside with some WD-40 or GT85 can sort it

mattyfez · April 2017

Actually I think I've still got my old 3x8 sram x4 shifters.
I upgraded to some second hand x9 shifters which someone on another forum sent me for free, so in the spirit of good will, you can have them.
They are used but mechanically sound.

So if your stuck, pm me your address and I'll post them to you.

larkim · April 2017

huggy_bizzle wrote:

I do know that the trigger came from a hybrid bike that used to run on a double chainset. The right hand trigger works perfectly fine though. I'll check gear tension tomorrow and get back to you guys.

Thanks again

If it used to run a double, what have you done to make it work fine with the triple that it is now on? I know some Shimano FD shifters have a switch to enable triple or double mode - is that the same on the SX4?

mattyfez · April 2017

If it used to run a double, what have you done to make it work fine with the triple that it is

It doesn't work if I've read the OP correctly, it just drops straight from 3 to 1.

You could probably make a sram 3 speed shifter work on a double chain ring, using the limit screws, and lose gear 1or 3.

But it doesn't sound like that's what the problem is here. It sounds like the shifter is broken or clogged with dirt or something.

Or its a 2 speed shifter.

JGTR · April 2017

So it's the wrong shifter :roll:

mattyfez · April 2017

JGTR wrote:

So it's the wrong shifter :roll:

Possibly but no need for the rolling eyes, we're just trying to help.

I read sx4 as sram x4, but maybe 'sx4' is a two speed shifter.

I have a carrera vengeance and it's stock configuration is 3x8, using sram x4 shifters. So I'm not sure if 'sx4' is something else or just an abbreviation.

huggy_bizzle · April 2017

Hi guys, thanks again, it appears to be all sorted now.

Yes the shifter is definitely 3 speed, it came on a 2008 Carrera Subway 2 if I remember correctly. It belonged to a friend of mine. He later had the double chainset and derailleur replaced with a triple chainset and derailleur at Halfords and they kept the same shifters.

Anyways, what I did: as suggested by 'The Rookie', I loosened the gear cable and pulled it through a little so that I could get the GT85 nozzle inside the trigger. I blasted in some fluid and worked the switch a bit. It seems to be fine now so fingers crossed, must of been some crud trapped in there somewhere.

Thank you mattyfez for offering your spare X4 triggers, it is very much appreciated. For the moment, I will see how we get on with the now fixed SX4 trigger.

I think that maybe the SRAM SX4 shifters have been replaced by the X4, they are both 3x8 configuration. The triggers are a little different though. The X4's are operated by the thumb only and the SX4's are operated by thumb and index finger, much like Shimano Deore 590 triggers for example, although the 2 triggers are joined together as one and kinda pivot together. I believe these to be dicontinued now.

Thanks again for all your help, it's nice to see there is plenty of help out there when you have some technical questions relating to bike mechanics, i'm sure i'll have plenty more qustions to ask in the near future.

SRAM SX4 Front Derailleur Trigger Issue

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