Chainring replacement?

dave @ stejonda said:

Having decided to fix up my tourer myself, I've begun the
process of stripping it down and have discovered that all
the chain rings have a number of broken/worn teeth. I
don't remember having this problem in my younger years!

Can I just replace the chainrings? They seem to be Shimano
SG-X which I can't find in any of the on-line catalogues.
Have they been superseded? Would other rings fit? Are the
fittings standardised?

Or would it make more sense to replace the cranks as well
as a set?

Looking on the web it appears that these rings are made of
some form of alloy. Could I replace them with something
tougher?

All suggestions/thoughts very welcome.

You will almost certainly be able to use any chainring that
fits. You need to count the number of arms on the
spider/number of retauning bolts, usually four or five and
calculate/measure the diameter of the circle on which the
chainring retaining bolts lie, this is the PCD. My 1988
Sugino GT has five arms and a PCD of 110mm. Old Shimano MTB
are the same for the outer rings, new Shimano road are 130mm
for a double and 130/74mm for a triple chainset.

TA and Stronglight are the best and more expensive
chanrings. Checkout Settle Cycles or Xpedia for the ranges.

dave @ stejonda said:

Having decided to fix up my tourer myself, I've begun the
process of stripping it down and have discovered that all
the chain rings have a number of broken/worn teeth.

Are you sure they weren't always like that? Broken chainring
teeth aren't all that common.

Quoted message said:

I don't remember having this problem in my younger years!

Older chainrings had more simple teeth. Many modern ones
have all sorts of peculiar shapes and half-teeth to "aid
shifting". Some look really terrible but they are supposed
to be like that.

Quoted message said:

Can I just replace the chainrings? They seem to be Shimano
SG-X which I can't find in any of the on-line catalogues.
Have they been superseded? Would other rings fit? Are the
fittings standardised?

What are the cranks? SG-X? Hopefully a Shimano expert will
help you further. Non-rivetted types are replaceable; they
are standardised to a certain extent. Most important
specifications are number of bolt holes or "arms" and bolt
circle diameter or BCD (or PCD: pitch circle diameter,
same thing).

Quoted message said:

Or would it make more sense to replace the cranks as well
as a set?

It can sometimes be cheaper to do that, sadly, but note that
any new cranks must be suitable for the existing bottom
bracket, otherwise cost of new BB would need to be taken
into account as well.

Quoted message said:

Looking on the web it appears that these rings are made of
some form of alloy. Could I replace them with something
tougher?

Steel rings are available for some types & sizes and should
last longer. Aluminium is usually ok though. You could test
yours with a magnet to make sure.

~PB

dave @ stejonda said:

Having decided to fix up my tourer myself, I've begun the
process of stripping it down and have discovered that all
the chain rings have a number of broken/worn teeth. I
don't remember having this problem in my younger years!

Can I just replace the chainrings? They seem to be Shimano
SG-X which I can't find in any of the on-line catalogues.
Have they been superseded? Would other rings fit? Are the
fittings standardised?

Or would it make more sense to replace the cranks as well
as a set?

Looking on the web it appears that these rings are made of
some form of alloy. Could I replace them with something
tougher?

All suggestions/thoughts very welcome.

Wiggle sell old-size Shimano rings to fit.

[email hidden] schreef ...

Quoted message said:

Wiggle sell old-size Shimano rings to fit.

Or else you can get Spécialités TA rings which will
almost always have the correct size. For (much) less
money than Shimano!

--
Regards, Marten

On Sun, 21 Mar 2004 18:27:59 +0100, Marten Hoffmann
<[email hidden]> wrote in message
<[email hidden]>:

Quoted message said:

Or else you can get Spécialités TA rings which will
almost always have the correct size. For (much) less
money than Shimano!

And last for ever ;-)

--
Guy
===
May contain traces of irony. Contents liable to settle after
posting. chapmancentral.co.ukchapmancentral.co.ukOpen ↗

88% of helmet statistics are made up, 65% of them at
Washington University

dave @ stejonda said:

Can I just replace the chainrings? They seem to be Shimano
SG-X which I can't find in any of the on-line catalogues.
Have they been superseded? Would other rings fit? Are the
fittings standardised?

I've been looking into this subject myself recently and from
what I've found it seems to me that it's definitely easier
and cheaper to buy a whole new chainset - of course, as Pete
says, this is likely to mean needing to buy a new bottom
bracket as well, but if it's an old bike that has never had
the BB replaced then chances are that it probably also needs
replacing anyway. I know my BB definitely needs replacing*,
which is a good opportunity to upgrade from cup-and-axle to
splined cassette-type BB.

d.

*the axle wobbles - I'm sure it's a problem with the BB
rather than the cranks because the cranks and axle move as
an ensemble. Maybe the axle is worn as well, but in any case
the whole bugger needs replacing

Just zis Guy said:

On Sun, 21 Mar 2004 18:27:59 +0100, Marten Hoffmann
<[email hidden]> wrote in message
<[email hidden]>:

Quoted message said:

Or else you can get Spécialités TA rings which will almost
always have the correct size. For (much) less money than
Shimano!

And last for ever ;-)

Indeed. I bought some to replace the 105 rings that were
made of cheese (lasting just 3000 miles) and so after
4000 miles on te TA rings when the chain was up for
replacement I bought some more only to find that the
original ones are still fine (I could not afford to have
the bike out of action if the chain slipped as I commute
on it). I still have the new rings in their packaging
12,000 miles further on.

--chris

"dave @ stejonda" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Having decided to fix up my tourer myself, I've begun the
process of stripping it down and have discovered that all
the chain rings have a number of broken/worn teeth. I
don't remember having this problem in my younger years!

Can I just replace the chainrings? They seem to be Shimano
SG-X which I can't find in any of the on-line catalogues.
Have they been superseded? Would other rings fit? Are the
fittings standardised?

Or would it make more sense to replace the cranks as well
as a set?

Looking on the web it appears that these rings are made of
some form of alloy. Could I replace them with something
tougher?

All suggestions/thoughts very welcome.

--
dave @ stejonda

Hard to pick the right post to respond to, so I've gone for
the original!

SG-X is not the chainset model, just a subset of specific
rings, from what I can remember. I think that they'll be the
old 110mm PCD rings, but they may equally be 94mm. You need
to measure them *carefully* - PCD (pitch circle diameter)
refers to the centre of the chainring fixing bolts (the ones
of which there are five, and which are retaining the
chainring you wish to replace). The 110/94mm is hard to
measure - it's easier to measure radius, which is, of
course, the distance from the crank fixing bolt to any one
of the chainring fixing bolts. The measurement will
obviously be 55mm or 47mm - or half of the 110/94, in other
words. I can't overemphasise the need for careful
measurement - because it's a relatively small difference,
and the crank sits proud of the ring (so that you're not
measuring the true radius / diameter of the bolts), it's
easy to make a mistake.

Having found out which PCD you need, take the advice of
other posters and buy a TA ring from Settle. They *are* more
expensive, but are far better. They'll last far longer, and
are better value in the long run. Stronglight a nd TA are
neither the same company or the same quality. Here speaks
someone who used to be one of the main retailers of
Stronglight in the UK.

Having said all of this, the poster who has remarked that
the teeth may not in fact be broken is dead right. Shimano
rings have a number of "lowered" teeth, which are designed
to improve gear change. I share that poster's scepticism
about your problem! Take advice before losing sight of £30
for a new ring....

Hope this helps.

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In message <[email hidden]>, Simon Daw
<[email hidden]> writes

Quoted message said:

"dave @ stejonda" <[email hidden]> wrote
in message "]news:[email hidden]...

Quoted message said:

Having decided to fix up my tourer myself, I've begun the
process of stripping it down and have discovered that all
the chain rings have a number of broken/worn teeth.

Can I just replace the chainrings? They seem to be
Shimano SG-X which I can't find in any of the on-line
catalogues. Have they been superseded? Would other rings
fit? Are the fittings standardised?

<>

Quoted message said:

SG-X is not the chainset model, just a subset of specific
rings, from what I can remember. I think that they'll be
the old 110mm PCD rings, but they may equally be 94mm. You
need to measure them *carefully*

<>

Quoted message said:

it's easy to make a mistake.

Thanks for that detailed explanation.

Quoted message said:

Having found out which PCD you need, take the advice of
other posters and buy a TA ring from Settle. They *are*
more expensive, but are far better.

Ok, I will if I need to.

Quoted message said:

Having said all of this, the poster who has remarked that
the teeth may not in fact be broken is dead right. Shimano
rings have a number of "lowered" teeth, which are designed
to improve gear change. I share that poster's scepticism
about your problem! Take advice before losing sight of £30
for a new ring....

Maybe I could scan the outer ring and place it on a web-page
for the 'panel's perusal.

--
dave @ stejonda

"To materialist eyes, India is a developing country; to
spiritual eyes, the United States is a developing
country." Ram Dass

In message <[email hidden]>,
Pete Biggs <[email hidden]> writes

Quoted message said:

dave @ stejonda said:

Having decided to fix up my tourer myself, I've begun the
process of stripping it down and have discovered that all
the chain rings have a number of broken/worn teeth.

Are you sure they weren't always like that? Broken
chainring teeth aren't all that common.

This is the first time I've looked at them this closely.
Looking at them again now they don't look broken, just oddly
shaped. What puzzles me now then is that the reduced ones
aren't placed symmetrically around the ring but at seemingly
random places. <>

Quoted message said:

Quoted message said:

Looking on the web it appears that these rings are made
of some form of alloy. Could I replace them with
something tougher?

Steel rings are available for some types & sizes and should
last longer. Aluminium is usually ok though. You could test
yours with a magnet to make sure.

Definitely non-ferric.

I'm going to go to Settle's www-site to have a look at the
alternatives but I'm coming round to thinking that I'm
seeing a problem that isn't there.

Thanks Pete, and everyone else. 🙂

--
dave @ stejonda

In message <[email hidden]>, david
kenning <[email hidden]> writes

Quoted message said:

dave @ stejonda said:

Can I just replace the chainrings? They seem to be
Shimano SG-X which I can't find in any of the on-line
catalogues. Have they been superseded? Would other rings
fit? Are the fittings standardised?

I've been looking into this subject myself recently and
from what I've found it seems to me that it's definitely
easier and cheaper to buy a whole new chainset - of course,
as Pete says, this is likely to mean needing to buy a new
bottom bracket as well, but if it's an old bike that has
never had the BB replaced then chances are that it probably
also needs replacing anyway.

The BB seems snugly fine. It obviously needs more use. ;-)

--
dave @ stejonda

dave @ stejonda suggested -

Quoted message said:

Maybe I could scan the outer ring and place it on a web-
page for the 'panel's perusal.

Please do - and/or email me (remove NOSPAM).

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"david kenning" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I've been looking into this subject myself recently and
from what I've

found

Quoted message said:

it seems to me that it's definitely easier and cheaper to
buy a whole new

Only with cheap sets is it not worth buying rings - and even
then it's not always the case. Just because a top quality
ring costs more than a basic chainset doesn't mean it's not
good value. It's like saying, "I'm not going to buy a new
engine for my Ferrari, because a complete Vauxhall Corsa is
cheaper"! The cheap chainset's not going to do the same job.

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In message <[email hidden]>, Simon Daw
<[email hidden]> writes

Quoted message said:

dave @ stejonda suggested -

Quoted message said:

Maybe I could scan the outer ring and place it on a web-
page for the 'panel's perusal.

Please do - and/or email me (remove NOSPAM).

In fact I've taken another look at the rings, this time in
silhouette, and I can see that there is a symmetry in the
deformations. Weird though!

Thanks for all the advice and suggestions.

--
dave @ stejonda

"dave @ stejonda" <[email hidden]> wrote -

Quoted message said:

In fact I've taken another look at the rings, this time in
silhouette, and I can see that there is a symmetry in the
deformations. Weird though!

Thanks for all the advice and suggestions.

You're not the first! ;-)

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