Front derailleur problem?

[Jason Spaceman]

I have a 2004 Trek 5200 with a double chainring and Ultegra derailleurs, brakes,
crank, etc.

Every so often, when I am climbing, I will attempt to shift from the large chainring
to the small ring. Instead of the chain shifting to the small ring it will fall off
onto the bottom bracket frame shell. I then have to stop, get off the bike, and
move the chain back onto the small ring.

I'm wondering what the problem could be. Does the front derailleur or shifter need
adjusting? This only happens when I am climbing, and even then only once every so
often; but it can be a pain in the ass.



J. Spaceman


--
My email address ([email protected]) is fake. Email sent to it will
only get caught in my spam tarpit.

 

[Qui si parla Campagnolo]

reply-<< Every so often, when I am climbing, I will attempt to shift from the
large chainring
to the small ring. Instead of the chain shifting to the small ring it will
fall off
onto the bottom bracket frame shell. I then have to stop, get off the bike,
and
move the chain back onto the small ring. >><BR><BR>
<< I'm wondering what the problem could be. Does the front derailleur or
shifter need
adjusting? >><BR><BR>

Chain is on the bigger cogs I suspect and the chain angle is toward the
frameset. Have a good wrench massage the front der. They can sometimes be
tricky.


Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

 

[Paul Kopit]

On Wed, 28 Jul 2004 07:49:48 -0400, Jason Spaceman
<[email protected]> wrote:

>Every so often, when I am climbing, I will attempt to shift from the large chainring
>to the small ring. Instead of the chain shifting to the small ring it will fall off
>onto the bottom bracket frame shell. I then have to stop, get off the bike, and
>move the chain back onto the small ring.
>
>I'm wondering what the problem could be. Does the front derailleur or shifter need
>adjusting? This only happens when I am climbing, and even then only once every so
>often; but it can be a pain in the ass.

Don't shift to a smaller ring when you are in the largest cog. Drop a
cog or two and then shift to the smaller ring. When a chainring gets
worn, this problem occurs more frequently. If it bothers you, either
a Cateye Chain watcher or Jump Stop will get rid of the problem. My
favorite is the Jump Stop.

 

[Robert]

Jason Spaceman wrote:
> I have a 2004 Trek 5200 with a double chainring and Ultegra derailleurs, brakes,
> crank, etc.
>
> Every so often, when I am climbing, I will attempt to shift from the large chainring
> to the small ring. Instead of the chain shifting to the small ring it will fall off
> onto the bottom bracket frame shell. I then have to stop, get off the bike, and
> move the chain back onto the small ring.
>
> I'm wondering what the problem could be. Does the front derailleur or shifter need
> adjusting? This only happens when I am climbing, and even then only once every so
> often; but it can be a pain in the ass.

I still drop chains from time to time, but luckily I usually have pretty
good speed going, when I do so. So I stay in my seat, shift the front DR
to the big ring position and carefully pedal until I get the chain back.
An alternative is to fish it up with your right hand as you ride, but
this is not good if you have white or yellow bar tape ;-)

The best solution is of course prevention, with Paul's and Peter's
advice. But the moment you have the chain sitting on the centre bracket
shell, you might want to try my way, but only if you're not going too
slow. YMMV and normal disclaimers apply.

/Robert

 

[[email protected]]

I'm a real good wrench.

I MTB 2004

 

[Trevor Jeffrey]

Jason Spaceman wrote in message <[email protected]>...
I have a 2004 Trek 5200 with a double chainring and Ultegra derailleurs,
brakes,
crank, etc.

Every so often, when I am climbing, I will attempt to shift from the large
chainring
to the small ring. Instead of the chain shifting to the small ring it will
fall off
onto the bottom bracket frame shell. I then have to stop, get off the bike,
and
move the chain back onto the small ring.

I'm wondering what the problem could be. Does the front derailleur or
shifter need
adjusting? This only happens when I am climbing, and even then only once
every so
often; but it can be a pain in the ass.



Chainring diff. too great. Loose BB. Loose crank. loose chainring. Gap
in fork of shifter too great. Rear wheel/chainstays out of alignment. BB
shell out of alignment. Cain tension insufficient. Overshift by mech..
Chainrings too close to each other.
All the above. I like half step.
TJ