TA chainring issue

Kyle.B.H said:

For two years now, I've been successfully running a triple crank with
50-40-28 Specialites TA chainrings. I recently purchased a new 38 tooth TA
ring for the middle (gearing down a bit for a tour) and noticed a difference
from the 40 tooth I purchased 2 years ago. On the newer 38t ring, the teeth
are tapered on only one side (the outside), and are flush with the restof
the ring on the inside. The 40 tooth is tapered symmetrically, from both
sides. The problem this is causing is that the inner plates of the chain
are catching on the top of each tooth while in the bottom three sprockets,
rendering these combinations noisy and, in the case of the bottom two,
unuseable (I realize that middle-small is a 'not-allowed' combination, but
it worked and used it occasionally). This didn't occur at all with the40
tooth (even in the bottom sprocket) and identical chainline (115 BB, 45mm
chainline). Just by looking at it, I'm sure I wouldn't have this issuewere
the teeth machined on both sides. A quick survey of every chainring I own -
big, middle, and granny - revealed that this is the only ring with teeth not
tapered from both sides. Is this a bum ring or did TA switch to a lousy
design? Should I get out my Dremel tool?

You don't say which series of chainrings you're using. If it's 130 BCD,
the smaller sizes are available in two different types, "inner" (for
doubles, marked "interieure" on the packaging) or "middle" for triples
(marked "intermediare".) The "middle/intermediare" models have shift
assist ramps and pins.

Sheldon "Spécialites T.A." Brown
+--------------------------------------------+
| Never worry about theory as long as the |
| machinery does what it's supposed to do. |
| --Robert A. Heinlein |
+--------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Quoted message said:

A quick survey of every chainring I own - big, middle, and
granny - revealed that this is the only ring with teeth not
tapered from both sides. Is this a bum ring or did TA switch
to a lousy design?

I just checked mine, and they're all double-tapered, so I'm thinking
your new ring missed a machining step, then slipped past inspection.

Quoted message said:

Should I get out my Dremel tool?

That's what I'd do.

--
"Bicycling is a healthy and manly pursuit with much
to recommend it, and, unlike other foolish crazes,
it has not died out." -- The Daily Telegraph (1877)

Quoted message said:

A quick survey of every chainring I own - big, middle, and
granny - revealed that this is the only ring with teeth not
tapered from both sides. Is this a bum ring or did TA switch
to a lousy design?

I just checked mine, and they're all double-tapered, so I'm thinking
your new ring missed a machining step, then slipped past inspection.

Quoted message said:

Should I get out my Dremel tool?

That's what I'd do.

--
"Bicycling is a healthy and manly pursuit with much
to recommend it, and, unlike other foolish crazes,
it has not died out." -- The Daily Telegraph (1877)

"Kyle.B.H" <[email hidden]> wrote in message news:<p2h2d.59860$D%.27603@attbi_s51>...

Quoted message said:

For two years now, I've been successfully running a triple crank with
50-40-28 Specialites TA chainrings. I recently purchased a new 38 tooth TA
ring for the middle (gearing down a bit for a tour) and noticed a difference
from the 40 tooth I purchased 2 years ago. On the newer 38t ring, the teeth
are tapered on only one side (the outside), and are flush with the rest of
the ring on the inside. The 40 tooth is tapered symmetrically, from both
sides. The problem this is causing is that the inner plates of the chain
are catching on the top of each tooth while in the bottom three sprockets,
rendering these combinations noisy and, in the case of the bottom two,
unuseable (I realize that middle-small is a 'not-allowed' combination, but
it worked and used it occasionally). This didn't occur at all with the 40
tooth (even in the bottom sprocket) and identical chainline (115 BB, 45mm
chainline). Just by looking at it, I'm sure I wouldn't have this issue were
the teeth machined on both sides. A quick survey of every chainring I own -
big, middle, and granny - revealed that this is the only ring with teeth not
tapered from both sides. Is this a bum ring or did TA switch to a lousy
design? Should I get out my Dremel tool?

Thanks,

Ah, but you are wrong my friend. This problem is independent of the
shape of the teeth. I run a Zephyr and have a 50 large. I found that
the rub starts when you go down below a 40T; I have it right now with
a 39T; I get the rub if I go to the two smallest cogs on the cassette,
so I just do not use those. The bigger the difference between outer
and middle the more it rubs; it really gets bad when I drop the middle
to a 36T. It all comes from the fact that the Zephyr has really tight
spacing between the rings; you can get rid of it a bit by putting thin
washers between the spider and the outer ring, thus spacing the outer
ring a bit further outboard. I do not bother; love the look and the
low Q, and can do without those two gears.

- rick

"Rick Warner" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"Kyle.B.H" <[email hidden]> wrote in message

news:<p2h2d.59860$D%.27603@attbi_s51>...

Quoted message said:

Quoted message said:

For two years now, I've been successfully running a triple crank with
50-40-28 Specialites TA chainrings. I recently purchased a new 38 tooth

TA

Quoted message said:

Quoted message said:

ring for the middle (gearing down a bit for a tour) and noticed a

difference

Quoted message said:

Quoted message said:

from the 40 tooth I purchased 2 years ago. On the newer 38t ring, the

teeth

Quoted message said:

Quoted message said:

are tapered on only one side (the outside), and are flush with the rest

of

Quoted message said:

Quoted message said:

the ring on the inside. The 40 tooth is tapered symmetrically, from

both

Quoted message said:

Quoted message said:

sides. The problem this is causing is that the inner plates of the

chain

Quoted message said:

Quoted message said:

are catching on the top of each tooth while in the bottom three

sprockets,

Quoted message said:

Quoted message said:

rendering these combinations noisy and, in the case of the bottom two,
unuseable (I realize that middle-small is a 'not-allowed' combination,

but

Quoted message said:

Quoted message said:

it worked and used it occasionally). This didn't occur at all with the

40

Quoted message said:

Quoted message said:

tooth (even in the bottom sprocket) and identical chainline (115 BB,

45mm

Quoted message said:

Quoted message said:

chainline). Just by looking at it, I'm sure I wouldn't have this issue

were

Quoted message said:

Quoted message said:

the teeth machined on both sides. A quick survey of every chainring I

own -

Quoted message said:

Quoted message said:

big, middle, and granny - revealed that this is the only ring with teeth

not

Quoted message said:

Quoted message said:

tapered from both sides. Is this a bum ring or did TA switch to a lousy
design? Should I get out my Dremel tool?

Thanks,

Ah, but you are wrong my friend. This problem is independent of the
shape of the teeth. I run a Zephyr and have a 50 large. I found that
the rub starts when you go down below a 40T; I have it right now with
a 39T; I get the rub if I go to the two smallest cogs on the cassette,
so I just do not use those. The bigger the difference between outer
and middle the more it rubs; it really gets bad when I drop the middle
to a 36T. It all comes from the fact that the Zephyr has really tight
spacing between the rings; you can get rid of it a bit by putting thin
washers between the spider and the outer ring, thus spacing the outer
ring a bit further outboard. I do not bother; love the look and the
low Q, and can do without those two gears.

You're describing a different issue than the one I'm having. This is not
rubbing of the chain on the big ring while in the middle ring. This is the
inner plates of the chain landing on the tops of the teeth of the middle
ring when using the smallest sprockets. Normally, the inner plate
(actually, the inner of the two inner plates) would hit the taper and slide
smoothly to the inside of the chainring. Since the teeth on this ring are
not tapered on the inside, but only from the outside, the tip of each tooth
is further leftwards than it would be were the machining done from both
sides - hence the problem.

"Sheldon Brown" <[email hidden]> wrote in message
news:[email hidden]...

Kyle.B.H said:

For two years now, I've been successfully running a triple crank with
50-40-28 Specialites TA chainrings. I recently purchased a new 38 tooth

TA

Quoted message said:

ring for the middle (gearing down a bit for a tour) and noticed a

difference

Quoted message said:

from the 40 tooth I purchased 2 years ago. On the newer 38t ring, the

teeth

Quoted message said:

are tapered on only one side (the outside), and are flush with the rest of
the ring on the inside. The 40 tooth is tapered symmetrically, from both
sides. The problem this is causing is that the inner plates of the chain
are catching on the top of each tooth while in the bottom three sprockets,
rendering these combinations noisy and, in the case of the bottom two,
unuseable (I realize that middle-small is a 'not-allowed' combination, but
it worked and used it occasionally). This didn't occur at all with the 40
tooth (even in the bottom sprocket) and identical chainline (115 BB, 45mm
chainline). Just by looking at it, I'm sure I wouldn't have this issue

were

Quoted message said:

the teeth machined on both sides. A quick survey of every chainring I

own -

Quoted message said:

big, middle, and granny - revealed that this is the only ring with teeth

not

Quoted message said:

tapered from both sides. Is this a bum ring or did TA switch to a lousy
design? Should I get out my Dremel tool?

You don't say which series of chainrings you're using. If it's 130 BCD,
the smaller sizes are available in two different types, "inner" (for
doubles, marked "interieure" on the packaging) or "middle" for triples
(marked "intermediare".) The "middle/intermediare" models have shift
assist ramps and pins.

This is a TA Alize 130 BCD middle ring. This particular ring is ramped and
pinned. Actually, I noticed the ramps and pins are more aggressive than the
40 tooth ring of 2 years ago. The issue is the tapering of the teeth.

Instead of (bad ascii art coming) the tips of the teeth looking like this
(from the rear, bottom): V

They look like this: |/ (also from the bottom of the ring, from the rear)

This is either a really bad design (like I said the ONLY ring I have like
this), or they missed a step in manufacturing.

I have an email into the supplier and I'm waiting to hear back.

Thanks,

Kyle