Front derailleur shifting problem

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Fraz101
Posts: 146
Joined: 15 Feb 2018, 12:47pm

Front derailleur shifting problem

Postby Fraz101 » 15 Feb 2018, 12:52pm

I have an issue with my front derailleur shifter.

It goes up the 3 rings perfectly but coming down from middle ring to bottom ring won’t go. If I just jump from top ring to bottom it will work tho.

I have a new chain and derailleur cable

I have removed derailleur and cleaned and lubricated. I’ve also adjusted cable tension and H and L screws to best of my ability

It is 3x7 speed.

Link to video for clarification

https://youtu.be/Wh0fiGPH0mU



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mercalia
Posts: 14578
Joined: 22 Sep 2013, 10:03pm
Location: london South

Re: Front derailleur shifting problem

Postby mercalia » 15 Feb 2018, 1:07pm

was it always that way and is it a new bike?
could be one of a few things -1) need to play around with the position of the derailleur on the down tube? others will adivce if you need to move it down bit 2) the inner screw needs adjusting to allow more movement, maybe a fraction of a turn - the new chain wont bend as much as an old one at first. if no amount of adjusting the inner screw dont help then was it like that always? 3) in my case I had some thing similar from new and Dawes had put on the wrong bottom bracket ( too short in my opinion I think was 115mm rather than 118mm, which was mentioned in the RSX specs for a triple ) meant the inner ring was too close to the downtube aand thus slighly beyond the deraileurs inner movement and needed a large shift ( large outer to inner ) to get there by brute force using any slack in the pieces

Brucey
Posts: 42870
Joined: 4 Jan 2012, 6:25pm

Re: Front derailleur shifting problem

Postby Brucey » 15 Feb 2018, 1:21pm

not all chains shift equally well; what chains have you used?

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Norman H
Posts: 964
Joined: 31 Jul 2011, 4:39pm

Re: Front derailleur shifting problem

Postby Norman H » 15 Feb 2018, 1:43pm

I can't add much to what others have said. Did you replace both inner and outer cables? Also did you check the plastic cable guide beneath the BB for wear? If badly worn the cable can bind here.

No harm in backing off the limit screw a fraction providing it doesn't overshift and derail the chain. Also worth checking that the mech actually contacts the limit stop.

Finally check the middle ring for excessive wear, it may be that it's badly worn and as a consequence is hanging on to the chain.

Fraz101
Posts: 146
Joined: 15 Feb 2018, 12:47pm

Front derailleur shifting problem

Postby Fraz101 » 15 Feb 2018, 2:20pm

New chain was fitted yesterday (sram)
The issue is exactly the same as with old chain (it was stretched)
Image



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mercalia
Posts: 14578
Joined: 22 Sep 2013, 10:03pm
Location: london South

Re: Front derailleur shifting problem

Postby mercalia » 15 Feb 2018, 5:15pm

so its not a new bike and was fine at some earlier time? if that is so was it ok on the previous chain? if so maybe loosen the links by pulling the chain sideways. So no amount of adjusting the inner screw will work?

reohn2
Posts: 40711
Joined: 26 Jun 2009, 8:21pm

Re: Front derailleur shifting problem

Postby reohn2 » 15 Feb 2018, 5:58pm

Have you tried turning the L stop screw 1/4 of a turn anti clockwise?
Is the outer deraileur cage plate bent or misshapen in any way?
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Fraz101
Posts: 146
Joined: 15 Feb 2018, 12:47pm

Re: Front derailleur shifting problem

Postby Fraz101 » 15 Feb 2018, 6:08pm

reohn2 wrote:Have you tried turning the L stop screw 1/4 of a turn anti clockwise?



Thank you for all replies.

I did this earlier and has cured the issue!

Thanks again guys

Ps what would you all reccomend I use to clean and lube my new chain?
I use the bike for communing to work, 6 miles per day over some pretty dirty back roads so bike is always caked in dirt,grit and road salt


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Brucey
Posts: 42870
Joined: 4 Jan 2012, 6:25pm

Re: Front derailleur shifting problem

Postby Brucey » 15 Feb 2018, 7:45pm

mudguards and good (non-standard) mudflaps go a long way to keeping the chain cleaner for longer. Whilst there is salt on the roads, some kind of wet lube/oil is probably best. Once the weather gets better you can use something else if you like. Winter is hard on chains.

For cleaning there are a gazillion ways of doing it, each having their advantages and advocates. If you have a SRAM chain with a quicklink, maybe you could have two chains and rotate them weekly or something. The chain that is off the bike can be cleaned and relubed at your leisure.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

reohn2
Posts: 40711
Joined: 26 Jun 2009, 8:21pm

Re: Front derailleur shifting problem

Postby reohn2 » 16 Feb 2018, 9:36am

Fraz101 wrote:

Ps what would you all reccomend I use to clean and lube my new chain?
I use the bike for communing to work, 6 miles per day over some pretty dirty back roads so bike is always caked in dirt,grit and road salt


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Buy a chain scrubber,Weldtite ones are good.
I use White Spirit in mine,then pour the used WS into an old jam jar with a lid,when the jar is full I leave it to settle and re use over again.
Once the chain has been run throught the scrubber,wipe the chain with the an old rag before lubing it.
The sprockets and chainrings can be cleaned with WS with an cheap paint brush.
I lube my chains with TF2 aerosol lube
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