Front Shifting Problems

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BrynCP

Über Member
Location
Hull
I posted about this in the past, although it was slightly different and the LBS fixed it during its service.

My front shifter doesn't like coming out the middle cog. Going from middle to smallest just doesn't happen when you ask it, and there is like no resistance in the shifter at all when moving between the two. Sometimes, if I shift to "1" and leave it for a while, sometime in the next few miles it will apparently at random finally move to the smallest cog. Any ideas?

(The last problem was the tension was there when shifting, and it was like it started to shift, but then sat between the two cogs and I'd have to shift back to the middle out of fear something was not right down on the cogs. This time it just makes no effort whatsoever).
 

helston90

Eat, sleep, ride, repeat.
Location
Cornwall
How old are the cables? Could they (and the outers) need replacing to allow the cable to move freely?
Does it all need a jolly good clean? especially if you've previously felt too much tension and now it won't drop down it does sound like a gunking up issue?
 

Broadside

Guru
Location
Fleet, Hants
If the LBS fixed it and the same problem has returned then I would take it back to them.

The problem could be due to a number of problems, most simply incorrect cable tension, but it could also be derailleur position which might need resetting. If it's a band-on derailleur then it may not be rotated correctly or could be too high/low. Could also be due to a derailleur cage which has gone out of alignment if you have ever had a chain that got badly jammed in it. With the exception of the twisted up derailleur due to chain damage scenario this is fixable at home yourself, but if you're not confident then I would take it back in to the LBS.
 
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BrynCP

Über Member
Location
Hull
How old are the cables? Could they (and the outers) need replacing to allow the cable to move freely?
Does it all need a jolly good clean? especially if you've previously felt too much tension and now it won't drop down it does sound like a gunking up issue?

The bike is 3 months old, same cables as new, about 750 miles in total. I do need to clean the bike, so weather permitting tomorrow I will be doing that.
 
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BrynCP

Über Member
Location
Hull
If the LBS fixed it and the same problem has returned then I would take it back to them.

The problem could be due to a number of problems, most simply incorrect cable tension, but it could also be derailleur position which might need resetting. If it's a band-on derailleur then it may not be rotated correctly or could be too high/low. Could also be due to a derailleur cage which has gone out of alignment if you have ever had a chain that got badly jammed in it. With the exception of the twisted up derailleur due to chain damage scenario this is fixable at home yourself, but if you're not confident then I would take it back in to the LBS.

There has been no damage to the derailleur to my knowledge, certainly never been a chain jammed in there.

I am going to give the bike a clean tomorrow and fit some mud guards, while I am doing that I will check all these things. I am not sure what a band-on means, but this is a Giant flat bar hybrid with an Altus derailleur.
 

Custom24

Über Member
Location
Oxfordshire
This might be too obvious, but there might be some crap in the derailleur mech which is preventing it from moving onto the small ring. I've regularly get that if I don't keep mine clean.
 

Broadside

Guru
Location
Fleet, Hants
I am not sure what a band-on means, but this is a Giant flat bar hybrid with an Altus derailleur.

Band-on means a derailleur that has a clamp that wraps around the seat tube. You can also get front derailleurs that fix to a point integral to the frame, but given it is Altus on a hybrid my money is on a band-on. There is more scope for incorrect setup with a band-on derailleur as rotation is a factor, but as said earlier if you are not confident with how it ought to be setup correctly then I would take it back to the LBS. It's not a difficult job but that is like saying it's easy to win Who Wants To Be A Millionaire; all you need to do is know all the answers, then it is easy ;-)
 

jack smith

Veteran
Location
Durham
surprised no one has mentioned new cables stretch, it could be a case of unscrewing the cable screw pulling the cable tight then re tighten then off you go
 

albion

Guru
No one has asked if you have adjusted the low screw. Turn it anti clockwise 1 turn.
 

raleighnut

Legendary Member
surprised no one has mentioned new cables stretch, it could be a case of unscrewing the cable screw pulling the cable tight then re tighten then off you go
Cable stretch would cause the exact opposite to this problem i.e. not wanting to go up to the middle ring . I would think its more a case of needing a bit of lubrication on both the shifter and cable, although it could be down to shifting to the granny ring too soon I myself wouldn't shift until I was in 2/2 then I would use both shifters to go to 1/3
 
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BrynCP

Über Member
Location
Hull
Well I cleaned it all up and it seemed to shift OK. There was nothing particular lodged in there, just a bit messy from road spray.

Unfortunately all this wind means I haven't actually ridden it and tried it yet but I am sure last time it did this, it shifted for a day, then stopped again.

Thanks for all your replies, I will certainly see how it goes when I next go out and adjust the low screw accordingly if necessary.
 

Custom24

Über Member
Location
Oxfordshire
You would see and/or hear the chain rubbing off the derailleur if it was the screw stop which needed adjusting. You would also see that the derailleur is not lined up over the small ring. I would leave the low screw alone personally until you rule out other issues. Could be too much cable tension, or just cable and or derailleur gunked up.

Clean the mech, release the cable completely (undo the nut so that the cable is detached), go to the largest sprocket on the rear. Where does the derailleur sit now? If still not quite over the small chain ring, then adjust the stop. You will see the derailleur move as you adjust the screw. If you are adjusting the stop back towards the large ring, then push the derailleur that way to help. In the other direction, the derailleur spring does this for you.
 

raleighnut

Legendary Member
A work stand or something else improvised helps enormously.
I would advise caution when removing the front shifter cable as resetting them can be a "bit of a b*****r" unless you know what you're doing. The only cog on a triple chainring to be affected by cable tension is the middle one and this position must be optimised in order to give maximum range on the rear without the chain "rubbing" on the front shifter especially if the front shift lever has a positive stop. As a competent cycle mechanic I regard fitting a full new cable set as just a maintainance job, as is fitting a new chain, but to the inexperienced it can be a minefield.
 
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