Front shifter fails after replacing crankset

[Daniel Kelly \]

Hi,

I've just upgraded my crankset and bottom bracket. And now I
can't change gears on the front derailleur. I've tried
moving and adjusting the front derailleur.

I think the problem may have 2 causes:

1) I have an old, worn, 8-speed chain. The crankset is 9-
speed. The 8-speed&9-speed combo shouldn't be a problem
but I suspect the old chain might be too worn to work. My
worry is that although people did tell me that shifting
performance would be 'poor', they didn't say the
performance would be non-existent. Since upgrading, it's
actually impossible to controllably change gear, even if
I push the derailleur way out. It's possible to change
from the large to the middle but impossible to go from
middle to large.

2) Before buying the BB and crankset, I read that the
crankset needs the longest available BB axel, so I got
121mm BB. But perhaps this is a little too long,
resulting in the front chainwheels being pushed too far
away from the frame?

My new BB is the Shimano LX Splined ES51 and the Crankset is
the LX Splined 9sp M571 170mm 22.32.44

I've taken some photos to illustrate my problem:

http://www.xlk.org.uk/forum/modules.php?set_albumName=Gea-
r_problems&op=modload&name=gallery&file=index&include=vie-
w_album.php

Thanks in advance for your help, Jack

[Dan Daniel]

On Sun, 11 Jul 2004 17:05:14 +0100, "Daniel Kelly \(AKA Jack\)"
<d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote:

>Hi,
>
>I've just upgraded my crankset and bottom bracket. And now
>I can't change gears on the front derailleur. I've tried
>moving and adjusting the front derailleur.
>
>I think the problem may have 2 causes:
>
>1) I have an old, worn, 8-speed chain. The crankset is 9-
> speed. The 8-speed&9-speed combo shouldn't be a problem
> but I suspect the old chain might be too worn to work.
> My worry is that although people did tell me that
> shifting performance would be 'poor', they didn't say
> the performance would be non-existent. Since upgrading,
> it's actually impossible to controllably change gear,
> even if I push the derailleur way out. It's possible to
> change from the large to the middle but impossible to go
> from middle to large.
>
>2) Before buying the BB and crankset, I read that the
> crankset needs the longest available BB axel, so I got
> 121mm BB. But perhaps this is a little too long,
> resulting in the front chainwheels being pushed too far
> away from the frame?
>
>My new BB is the Shimano LX Splined ES51 and the Crankset
>is the LX Splined 9sp M571 170mm 22.32.44
>
>I've taken some photos to illustrate my problem:
>
>http://www.xlk.org.uk/forum/modules.php?set_albumName=Gear-
>_problems&op=modload&name=gallery&file=index&include=view_-
>album.php
>
>Thanks in advance for your help, Jack
>

Looking at pictures 5, 6 and 7, your front derailleur is
positioned very high, far away from the chainrings. It's
going to be hard to get clean shifting with it so high.

http://www.sheldonbrown.com/derailer-adjustment.html#front

You might start from scratch and follow these steps
one by one.

[Sheldon Brown]

Daniel Kelly (AKA Jack) wrote:
>
> I've just upgraded my crankset and bottom bracket. And
> now I can't
change
> gears on the front derailleur. I've tried moving and
> adjusting the front derailleur.
[snip]
> 2) Before buying the BB and crankset, I read that the
> crankset needs the longest available BB axel, so I got
> 121mm BB.

Bingo, there's your problem!

> But perhaps this is a little too long, resulting in the
> front chainwheels being pushed too far
away from
> the frame?

Right.

> My new BB is the Shimano LX Splined ES51 and the Crankset
> is the LX
Splined
> 9sp M571 170mm 22.32.44

See: http://sheldonbrown.com/bbsize.html#deore

Your cranks _should_ have a 113 mm spindle, if the bike has
a normal-sized seat tube, 118 only if it has a fat seat
tube. (Fat seat tubes place the front derailer mechanism
farther outboard.)

Sheldon "Chainline" Brown +---------------------------------------------------
+
| Time shouldn't just pass; things should happen. | --Harry
| Turtledove |
+---------------------------------------------------+ Harris
Cyclery, West Newton, Massachusetts Phone 617-244-9772 FAX
617-244-1041 http://harriscyclery.com (http://harriscyclery.com/) Hard-to-find parts
shipped Worldwide http://captainbike.com (http://captainbike.com/)
http://sheldonbrown.com (http://sheldonbrown.com/)

[Daniel Kelly \]

Hi Sheldon,

Thanks loads for your reply.

I'm not sure if I have a "fat seat tube". My bike is a 2002
Trek 4300 - the specs claim the bike has an 'oversized Alpha
aluminium' frame with 'oversized powertubes'. The full specs
are here:
http://www.trekbikes.com/bikes/2002/mountain/4300.html#

Also, I'm a little worried about getting a smaller BB
because the left crank is only a mm or so away from the BB
housing on my 121mm BB. If I swap my 121mm BB for a 118 mm
BB, will those 3mm be lost from both sides of the axel
(i.e. bringing both the left and right cranks 1.5mm closer
to the BB) or just from the right side of the axel
(i.e. the left crank position will be exactly the same
on both the 121 and 118mm BBs but the right crank will
be 3mm closer)?

Thanks, Jack

"Sheldon Brown" <captbike@sheldonbrown.com> wrote in message
news:40F1733B.1080106@sheldonbrown.com...
> Daniel Kelly (AKA Jack) wrote:
> >
> > I've just upgraded my crankset and bottom bracket. And
> > now I can't
> change
> > gears on the front derailleur. I've tried moving and
> > adjusting the
front
> > derailleur.
> [snip]
> > 2) Before buying the BB and crankset, I read that the
> > crankset needs
the
> > longest available BB axel, so I got 121mm BB.
>
> Bingo, there's your problem!
>
> > But perhaps this is a little too long, resulting in the
> > front chainwheels being pushed too far
> away from
> > the frame?
>
> Right.
>
> > My new BB is the Shimano LX Splined ES51 and the
> > Crankset is the LX
> Splined
> > 9sp M571 170mm 22.32.44
>
> See: http://sheldonbrown.com/bbsize.html#deore
>
> Your cranks _should_ have a 113 mm spindle, if the bike
> has a normal-sized seat tube, 118 only if it has a fat
> seat tube. (Fat seat tubes place the front derailer
> mechanism farther outboard.)
>
> Sheldon "Chainline" Brown +---------------------------------------------------
> +
> | Time shouldn't just pass; things should happen. | --
> | Harry Turtledove |
> +---------------------------------------------------+
> Harris Cyclery, West Newton, Massachusetts Phone 617-244-
> 9772 FAX 617-244-1041 http://harriscyclery.com (http://harriscyclery.com/) Hard-to-
> find parts shipped Worldwide http://captainbike.com (http://captainbike.com/)
> http://sheldonbrown.com (http://sheldonbrown.com/)

[Russell Seaton]

> See: http://sheldonbrown.com/bbsize.html#deore
>
> Sheldon "Chainline" Brown Harris Cyclery, West Newton,
> Massachusetts Phone 617-244-9772 FAX 617-244-1041
> http://harriscyclery.com (http://harriscyclery.com/) Hard-to-find parts shipped
> Worldwide http://captainbike.com (http://captainbike.com/) http://sheldonbrown.com (http://sheldonbrown.com/)

Thank you Mr. Brown. Your website link confirmed my
measurement of my bottom bracket. I have a 1991 Deore DX
crankset and am going to replace the original Tange loose
ball and locknut bottom bracket with Shimano's cheap sealed
unit. I had measured the original bottom bracket and came up
with about 124mm so I figured the 122mm was the right
length. But its good to have confirmation.

[Werehatrack]

On Mon, 12 Jul 2004 12:43:42 +0100, "Daniel Kelly \(AKA Jack\)"
<d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote:

>Hi Sheldon,
>
>Thanks loads for your reply.
>
>I'm not sure if I have a "fat seat tube". My bike is a 2002
>Trek 4300 - the specs claim the bike has an 'oversized
>Alpha aluminium' frame with 'oversized powertubes'. The
>full specs are here:
>http://www.trekbikes.com/bikes/2002/mountain/4300.html#
>
>Also, I'm a little worried about getting a smaller BB
>because the left crank is only a mm or so away from the BB
>housing on my 121mm BB. If I swap my 121mm BB for a 118 mm
>BB, will those 3mm be lost from both sides of the axel
>(i.e. bringing both the left and right cranks 1.5mm closer
> to the BB) or just from the right side of the axel
> (i.e. the left crank position will be exactly the
> same on both the 121 and 118mm BBs but the right
> crank will be 3mm closer)?

There may be another fudge factor to look at. I've noted
that some Shimano BB units have about 2mm of unthreaded boss
between the threads and the right flange on the body; when
torqued as per spec into a BB shell that is threaded all the
way out, the flange may not seat against the shell as a
result. If there is a gap between the flange and the BB
shell in your installation, you've run aground on this
problem. This has happened to me twice; I've swapped to
using generic BBs for the moment to get around it. The
generics are uniformly threaded all the way to the flange.

--
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