Front derailleur not shifting on indoor trainer

[DavidE373]

I'm at a complete loss.. 

My gears all shift well when my wheel is spinning freely (no tension from the trainer) but as soon as I add tension from the trainer then the front derailleur won't shift, at all.. it moves but it's like there isn't enough movement to shift the chain on to the big ring.  If I start with the chain on the big ring then I can't shift down. I'm completely stumped! Any thoughts?

I'm using Tiagra shifters, 105 derailleurs, SRAM cassette and Tiagra chain (which are both new). 10 speed set up.

[robbybzgo]

It's possible that the tension in the derailleur cable needs to be adjusted...

You might also have a sticky cable (old/ frayed/ rusty) that is clogged with dirt.

Sometimes these problems are hard to pinpoint quickly. Make sure the front derailleur is also lubricated and moving freely.

Good luck.

[DavidE373]

Thanks for the reply.

The cables are fairly new, my bike was serviced not too long ago. They might be a little dirty, I store my bike on the wall under the carport and it’s been quite dusty with the wind blowing. I’ll check that out and see what difference it makes.

[RobertWhitehead]

It's a tension / cable issue. IMO, but I am no expert ????

[DavidE373]

2 hours ago, RobertWhitehead said:

It's a tension / cable issue. IMO, but I am no expert ????

I've played around with the tension to the point where I was the only thing becoming tense! Derailleur is set, cable tension is great when there's no resistance from the trainer. 

[Frosty]

I’m struggling to understand why the front derailleur would be influenced by the trainer.

Is your cable internally routed or the older style external?

Can you move the derailleur with with your fingers when no tension on the cable, or no cable connected?

Does your shifter work freely when no tension on the cable?

[DavidE373]

21 minutes ago, Frosty said:

I’m struggling to understand why the front derailleur would be influenced by the trainer.

Is your cable internally routed or the older style external?

Can you move the derailleur with with your fingers when no tension on the cable, or no cable connected?

Does your shifter work freely when no tension on the cable?

I'm struggling to understand it as well.. cables are external. The gearing works when it's not on the trainer. I have no idea why it's affected by the tension of the trainer, apparently (seen on another forum when Googling the problem) it's a tension on the chain, not the cable, that's a problem. I'll test the bike on the road tomorrow and see how smoothly the gears change.