SRAM Apex front derailleur problem

[Magpies]

I'm trying out a bike fitted with a SRAM Apex drivetrain (50/34T compact crankset, chain, shifters, derailleurs, 10-speed 11-32T cassette) using the "double tap" shift system, and am posting to ask for advice.

The rear derailleur shifts sweetly and precisely, but I'm having a problem with the front one.

When the bike is on my repair stand, the front derailleur shifts easily from 50 to 34T and back again, all works as it should.

However, when I'm riding the bike, the front shifts don't work. Pressing the shifter causes a loud "clunk" but no shift. When that happens, there is slack in the shifter, and I have to press it again a couple of times to "prime" it. Sometimes, the 50 to 34T shift works after repeated tries, but I've never managed to shift from 34 to 50T when riding. Back home, on the stand - and it works again !?!

Any advice please?

 

[iluvmybike]

I have found that the cable tension on SRAM fds needs to be quite tight. Press the shift lever sufficient times to make sure that any 'trim' has been taken out then slacken the cable off at the fd. Then tyake up any slack & secure the cable and then adjust via the barrel adjuster -assuming you have one - if not best to fit one! It is easier to adjust the tension with the fd in the little ring

 

[Magpies]

Thank you. I do have a barrel adjuster and will try this out.

 

[bikingdad90]

If I remember correctly the Sram shifters have two trim positions. One for the little cog and one for the big cog. I believe it is short press for the trims and big swing to change up/down.

As your hearing a clunk I’d be tempted to remove the inner and then replace it and check the routing for any kinks.

 

[cyberknight]

I will echo above
the cable does need to be tight and you need a long throw to get it in the big ring, i did find when i used a third party FD it did a loud clunk when shifting to the small which seemed to work better when i changed to a sram FD.

 

[Magpies]

Thank you both. I've tightened the cable as suggested, and it improved matters somewhat in that I have been able to get the chainrings to shift in both directions while riding the bike. But it's still inconsistent.

I hadn't appreciated the 'short press=trim, long throw=shift' connection for the SRAM front shifter. Makes sense now what I need to do.

Can't wait to have another go - once it stops pouring with rain!

 

[cyberknight]

does it need recalbling ?

 

[Magpies]

I think not. The cables look in good nick, and I was able to tighten them without problems. I suspect I just need to get used to the SRAM fd shifters.

 

[Magpies]

Thanks to everyone for the advice. Sorted now. SRAM fd cabling needs to be tight ..... mine now twangs like a guitar string ..... but it works once adjusted, and once I got used to the 'long throw' of the shifter to move to the big chainring.