lateral movement in front chainrings

Philip Egan

Hi,

Just wondering how serious this was? The whole chainring /
spider has slight left to right movement when you rotate the
crank. I've removed the chainrings themselves to have a
look, and they're ok. Crank seems tight too.

Am i going to have to remove / replace the whole bottom
bracket? Any thoughts anyone?

Cheers, Phil

Ron Hardin

Before there were modern components, you just tightened up
the bearings a little and then back off slightly. I have no
idea if modern BBs have an adjustment even. Mine does.

Leave it slightly loose out of respect for its having worn
unevenly, otherwise the bearings won't last long.
--
Ron Hardin rhhardin@mindspring.com

On the internet, nobody knows you're a jerk.

Dan Daniel

On Sun, 27 Jun 2004 22:20:33 +0100, "Philip Egan"
<philip.egan2@ntlworld.com> wrote:

>Hi,
>
>Just wondering how serious this was? The whole chainring /
>spider has slight left to right movement when you rotate
>the crank. I've removed the chainrings themselves to have a
>look, and they're ok. Crank seems tight too.
>
>Am i going to have to remove / replace the whole bottom
>bracket? Any thoughts anyone?
>
>Cheers, Phil
>

Do you mean that the chainrings appear to wobble left to
right as you spin the crank? Is this consistent- same spot
on the chainring wobbling each time?

When you remove the chainrings, can you see any wobble at
the end of each spider arm with respect to each other? Use
the derailleur cage as a marker and check carefully.

I fixed a chainring wobble by bending the tabs at the end of
the spider arms on the crank itself. I used a large
adjustable/crescent wrench and very lightly moved the
appropriate tabs in or out. Using a black clamped to the
downtube and claipers I was able to get each tab within
.003" of each other....

As usual, Sheldon Brown has laid this all out much better
than I ever will-

http://www.sheldonbrown.com/straighten_chw.html

Werehatrack

On Sun, 27 Jun 2004 22:20:33 +0100, "Philip Egan"
<philip.egan2@ntlworld.com> wrote:

>Hi,
>
>Just wondering how serious this was? The whole chainring /
>spider has slight left to right movement when you rotate
>the crank. I've removed the chainrings themselves to have a
>look, and they're ok. Crank seems tight too.
>
>Am i going to have to remove / replace the whole bottom
>bracket? Any thoughts anyone?

If it's cyclic and constant with crank rotation, the crank
is not square with the BB shaft; this is often a sign that
the square taper is slightly wallowed or that the right
crank may be bent. If it's side-to-side slop that can be
observed without rotating the crank, then the BB is
probably loose, worn, or in need of adjustment, depending
on the design.

--
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