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FRONT DERALIEUR NOT WORKING
#1
Hi guys,

I have restored a 90' Fisher mountain bike. It works perfectly apart from the front derailleur. Gears goes down no problem. They go up from the first to second cog no problem but it is very difficult to make it go to the biggest gear. This is an old SRAM groupset.

It is not the cable tension, not the limit screws and not the position of the derailleur on the frame. These are the basic things I have checked. The chain is well oiled.
When turning the lever on the handlebar to go up from the second to the third front gear the derailleur move freely and swiftly, it gets stuck against the chain but still the chain is not going up!!!!!. I do not understand why.

Only if I go from the first to the third gear seems to work most times, but not always. it moves from first to second gear perfectly but not from second to third. What should I look at?
The derailleur position seems correct. above 1-2 mm from the biggest cog.

I am just wondering if the derailleur arm is bent (looks fine to me). I have tried with pliers to bend the arm cage so the the lower part is at an angle with the chain so that it can push it up but it did not improve. I can turn the lever on the handlebar so the arm pushes strongly against the chain but still the chain does not like to go up.

It is wired that it works fine from first to second. I have noticed that the derailleur arm cage has a different shape on its length and it touches different point when moving the chain from first- second in comparison to second-third. This is why I think there might be a problem with the cage although I cannot see anything evident.

Any suggestion will help. Thank you!

FM
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#2
The spring is worn and the derailleur needs replaced.

Front Derailleurs are very finicky and the springs seem to wear out so easily.

I've done away with all my 2x setups because I'm sick of dealing with them.
  Reply
#3
Hello, could you please add some photos? It would be useful to know which type of front derailleur is (top/high vs down/low pulling) and consider if it could be a problem related to the srping.
Can you say that the shifter is ok? Maybe it could be it the problem: it is more common that the internal mech give up rather than the spring of the front derailleur.
This kind of spring is very strong! [I've heard and seen brifters -even high quality shimano- broken due to the high friction caused by the cable and its housing poorly cleaned]
  Reply
#4
(09-14-2021, 03:27 PM)FabioMaria Wrote:  Hello, could you please add some photos? It would be useful to know which type of front derailleur is (top/high vs down/low pulling) and consider if it could be a problem related to the srping.
Can you say that the shifter is ok? Maybe it could be it the problem: it is more common that the internal mech give up rather than the spring of the front derailleur.
This kind of spring is very strong! [I've heard and seen brifters -even high quality shimano- broken due to the high friction caused by the cable and its housing poorly cleaned]

Agree on the strong spring unless rusted out. Never had a problem even on derailleurs over 40 yrs old; high end and cheaper (except the Simplex plastic/delrin models cracking). Sometimes worn/rusty pivot pins/bolts.
Ride Fast, Be Safe!
Howard
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