TA chainset problem

I have a problem with a TA chainset, making it possibly the most expensive non-replaceable rings
chainset ever.

The two big rings are held to teh crank spider in what is superficially the normal manner - a bolt
passes through middle ring, through spider arm, into socket which itself passes through the big ring
and into teh spider arm.

However, the sockets are not loose, they are fixed to teh big ring. The sockets are circular and
have no feature to which to apply torque.

One of the sockets is directly behind the crank arm, and this socket (while running the bolt into
it, but before the bolt has seated fully) has broken loose, so it now rattles. I think there must
have been a bit of grit in teh threads, because I can now neither undo and remove nor tighten
further the bolt / socket in question.

I can't get at the head of teh socket because it's behind the crank arm, so can't even grind a slot
in it and apply a screwdriver. Simply levering onto teh head with a screwdriver or similar does not
apply enough friction to hold it still - it rotates as I turn the bolt.

Suggestions? I don't don't want to replace a whole TA chainset when either of the rings needs
replacing.

regards, Ian SMith
--
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Last resort. If there's enough of a gap saw through the bolt and fit a new one with a slotted
nut.. Ken.

"Ian Smith" <[email protected]> wrote in message news:[email protected]...
> I have a problem with a TA chainset, making it possibly the most expensive non-replaceable rings
> chainset ever.
>
> The two big rings are held to teh crank spider in what is superficially the normal manner - a bolt
> passes through middle ring, through spider arm, into socket which itself passes through the big
> ring and into teh spider arm.
>
> However, the sockets are not loose, they are fixed to teh big ring. The sockets are circular and
> have no feature to which to apply torque.
>
> One of the sockets is directly behind the crank arm, and this socket (while running the bolt into
> it, but before the bolt has seated fully) has broken loose, so it now rattles. I think there must
> have been a bit of grit in teh threads, because I can now neither undo and remove nor tighten
> further the bolt / socket in question.
>
> I can't get at the head of teh socket because it's behind the crank arm, so can't even grind a
> slot in it and apply a screwdriver. Simply levering onto teh head with a screwdriver or similar
> does not apply enough friction to hold it still - it rotates as I turn the bolt.
>
> Suggestions? I don't don't want to replace a whole TA chainset when either of the rings needs
> replacing.
>
> regards, Ian SMith
> --
> |\ /| no .sig
> |o o|
> |/ \|

 

Ian Smith wrote:
> I have a problem with a TA chainset, making it possibly the most expensive non-replaceable rings
> chainset ever.
>
> The two big rings are held to teh crank spider in what is superficially the normal manner - a bolt
> passes through middle ring, through spider arm, into socket which itself passes through the big
> ring and into teh spider arm.
>
> However, the sockets are not loose, they are fixed to teh big ring. The sockets are circular and
> have no feature to which to apply torque.
>
> One of the sockets is directly behind the crank arm, and this socket (while running the bolt into
> it, but before the bolt has seated fully) has broken loose, so it now rattles. I think there must
> have been a bit of grit in teh threads, because I can now neither undo and remove nor tighten
> further the bolt / socket in question.
>
> I can't get at the head of teh socket because it's behind the crank arm, so can't even grind a
> slot in it and apply a screwdriver. Simply levering onto teh head with a screwdriver or similar
> does not apply enough friction to hold it still - it rotates as I turn the bolt.
>
> Suggestions? I don't don't want to replace a whole TA chainset when either of the rings needs
> replacing.
>
> regards, Ian SMith

Well, it would be a bit of a bodge, but I've had to do someting similar before now. Take the rest of
the bolts out. Put a screwdriver (or other suitable lever) between the chainrings, and twist to push
the chainrings apart, while unscrewing the remaining bolt. A little oil on the outside bolt will
help it turn easier than the socket, which should be held still by the pressure being applied to it,
as long as the thread is not totally siezed. I would tend to put it off until you need to replace a
chainring, too, as it may shake loose by then. If the rattling is too irritating, you may not want
to wait, or you could stick it with some thread lock (if its not too dirty).

Good luck.

JimP

 

On Sat, 15 Mar 2003, Kenneth Clements <[email protected]> wrote:

> Last resort. If there's enough of a gap saw through the bolt and fit a new one with a
> slotted nut..

Not enough gap - it's loose enough to rattle, but not loose enough that the head of either bolt or
socket comes fully out of teh recess they are seated in.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

 

On Sat, 15 Mar 2003 16:36:36 +0000, Jim Price <[email protected]> wrote:
> Ian Smith wrote:
> > I have a problem with a TA chainset, making it possibly the most expensive non-replaceable rings
> > chainset ever.
>
> Well, it would be a bit of a bodge, but I've had to do someting similar before now. Take the rest
> of the bolts out. Put a screwdriver (or other suitable lever) between the chainrings, and twist
> to push the chainrings apart, while unscrewing the remaining bolt. A little oil on the outside
> bolt will help it turn easier than the socket, which should be held still by the pressure being
> applied to it, as long as the thread is not totally siezed.

You mean prise the rings so that the head of the socket presses hard against what it's seated on?
That's what I thought of second (after simply trying to lever onto teh head of the socket with
enough pressure to hold it). It didn't work.

> I would tend to put it off until you need to replace a chainring, too, as it may shake loose
> by then.

That'd be good.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

 

"Ian Smith" <[email protected]> wrote in message news:[email protected]...
> I have a problem with a TA chainset, making it possibly the most expensive non-replaceable rings
> chainset ever.

[ snip ]

>
> One of the sockets is directly behind the crank arm, and this socket (while running the bolt into
> it, but before the bolt has seated fully) has broken loose, so it now rattles. I think there must
> have been a bit of grit in teh threads, because I can now neither undo and remove nor tighten
> further the bolt / socket in question.
>
> I can't get at the head of teh socket because it's behind the crank arm, so can't even grind a
> slot in it and apply a screwdriver. Simply levering onto teh head with a screwdriver or similar
> does not apply enough friction to hold it still - it rotates as I turn the bolt.
>
> Suggestions? I don't don't want to replace a whole TA chainset when either of the rings needs
> replacing.

Drill a small hole from the non-crank side in the flange of the socket. You'll have to go through
the "bolt" mating piece, and you MUST go through the flange of the sprocket on which the socket
bears. This is a job for a drill press & a hss bit, and and good eye and steady hand. A friend with
a machine-shop would be nice.

After you get the hole made, go in from the crank side with a small hex wrench, just far enough to
lock the socket to the sprocket flange. Then you can work on the bolt end.

Paul Jorgensen showed me this trick when I had an old TA crank where the bolt and socket were stuck
together, and the slots in the socket part were not enough. Bust two pin wrenches before I took it
to the Dutchman, who smiled. Normally he was doing stuff like turning a gasket surfaces on a section
of 6-foot diameter pipe; this small a problem was fun to him.

 

Ian Smith wrote:
> I have a problem with a TA chainset, making it possibly the most expensive non-replaceable rings
> chainset ever.
>
> The two big rings are held to teh crank spider in what is superficially the normal manner - a bolt
> passes through middle ring, through spider arm, into socket which itself passes through the big
> ring and into teh spider arm.
>
> However, the sockets are not loose, they are fixed to teh big ring. The sockets are circular and
> have no feature to which to apply torque.
>
> One of the sockets is directly behind the crank arm, and this socket (while running the bolt into
> it, but before the bolt has seated fully) has broken loose, so it now rattles. I think there must
> have been a bit of grit in teh threads, because I can now neither undo and remove nor tighten
> further the bolt / socket in question.
>
> I can't get at the head of teh socket because it's behind the crank arm, so can't even grind a
> slot in it and apply a screwdriver. Simply levering onto teh head with a screwdriver or similar
> does not apply enough friction to hold it still - it rotates as I turn the bolt.
>
> Suggestions? I don't don't want to replace a whole TA chainset when either of the rings needs
> replacing.

I've got a feeling I've read about a proper tool or technique for dealing with this from Sheldon
Bown on rec.bicycles.tech. Can't find it now, sorry.

Calling Sheldon Brown. Can you help Ian?

(SB sometimes searches this group). If no answer here, you could try emailing him.

~PB

 

Ian Smith wrote:
> On Sat, 15 Mar 2003 16:36:36 +0000, Jim Price <[email protected]> wrote:
>
>> Ian Smith wrote:
>>
>>>I have a problem with a TA chainset, making it possibly the most expensive non-replaceable rings
>>>chainset ever.
>>
>> Well, it would be a bit of a bodge, but I've had to do someting similar before now. Take the rest
>> of the bolts out. Put a screwdriver (or other suitable lever) between the chainrings, and twist
>> to push the chainrings apart, while unscrewing the remaining bolt. A little oil on the outside
>> bolt will help it turn easier than the socket, which should be held still by the pressure being
>> applied to it, as long as the thread is not totally siezed.
>
>
> You mean prise the rings so that the head of the socket presses hard against what it's seated on?
> That's what I thought of second (after simply trying to lever onto teh head of the socket with
> enough pressure to hold it). It didn't work.
>

That pesky "enough" word never works as well as it should.

>
>> I would tend to put it off until you need to replace a chainring, too, as it may shake loose
>> by then.
>
>
> That'd be good.

Just put some penetrating oil on it then, and ride on. I would imagine a TA chainring would last a
fair while anyway. You could try wearing out the outer ring first, so that when its replacement
time, you can just go for it with an angle grinder against the bolt head. The bolt is probably
recessed a little into the chainring, but if the chainring is worn out, cutting through that bit
with the angle grinder won't be much of a sacrifice.

JimP

 

On Sat, 15 Mar, jt <[email protected]> wrote:
>
> "Ian Smith" <[email protected]> wrote
>
> > I have a problem with a TA chainset, making it possibly the most expensive non-replaceable rings
> > chainset ever.
>
> [ snip ]
>
> Drill a small hole from the non-crank side in the flange of the socket. You'll have to go through
> the "bolt" mating piece, and you MUST go through the flange of the sprocket on which the socket
> bears. This is a job for a drill press & a hss bit, and and good eye and steady hand. A friend
> with a machine-shop would be nice.

I can't visualise this.

I can't simply drill out the bolt / socket because there's nothing stopping the two spinning (that's
the problem), but I don't think that's what you're suggesting.

From the non-crank side, any drilling into the socket other than down the shaft of the bolt
features drilling through some part of the crank spider arm, I think. Certainly, the flange of the
socket overlaps the crank arm, because the shaft of the socket is a snug fit within the hole in the
crank arm.

I can see how it'd work if it was one of teh other sockets and I could drill from the outer face
through socket flange into chainring (it's a more sophisticated variant of my grind-a-slot method),
but I don't think I want a hole in my crank arm.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

 

On Sun, 16 Mar 2003, Jim Price <[email protected]> wrote:
> Ian Smith wrote:
> > On Sat, 15 Mar 2003, Jim Price <[email protected]> wrote:
> >> Ian Smith wrote:
> >>
> >>> I have a problem with a TA chainset, making it possibly the most expensive non-replaceable
> >>> rings chainset ever.
> >>
> >> I would tend to put it off until you need to replace a chainring, too, as it may shake loose by
> >> then.
> >
> > That'd be good.
>
> Just put some penetrating oil on it then, and ride on. I would imagine a TA chainring would last
> a fair while anyway. You could try wearing out the outer ring first, so that when its replacement
> time, you can just go for it with an angle grinder against the bolt head.

That's about what I'm resigned to at the moment, except that I want the middle ring to wear out
first, since grinder against the bolt head will probably make a mess of the adjacent middle ring,
and I can't get at the socket head because of teh adjacent crank.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

 

"Ian Smith" <[email protected]> wrote in message news:[email protected]...
> On Sat, 15 Mar, jt <[email protected]> wrote:
> >
> > "Ian Smith" <[email protected]> wrote
> >
> > > I have a problem with a TA chainset, making it possibly the most expensive non-replaceable
> > > rings chainset ever.
> >
> > [ snip ]
> >
> > Drill a small hole from the non-crank side in the flange of the socket. You'll have to go
> > through the "bolt" mating piece, and you MUST go
through
> > the flange of the sprocket on which the socket bears. This is a job
for a
> > drill press & a hss bit, and and good eye and steady hand. A friend
with a
> > machine-shop would be nice.
>
> I can't visualise this.

I'll try again.

>
> I can't simply drill out the bolt / socket because there's nothing stopping the two spinning
> (that's the problem), but I don't think that's what you're suggesting.

Correct.

>
> From the non-crank side, any drilling into the socket other than down the shaft of the bolt
> features drilling through some part of the crank spider arm, I think. Certainly, the flange of the
> socket overlaps the crank arm, because the shaft of the socket is a snug fit within the hole in
> the crank arm.

That is exactly what you need to do. Drill from the non-crank side, through:
a) the "bolt" flange
b) the inner sprocket seating flange
c) the crank spider
d) the outer sprocket seating flange
e) the "nut" flange

>
> I can see how it'd work if it was one of teh other sockets and I could drill from the outer face
> through socket flange into chainring (it's a more sophisticated variant of my grind-a-slot
> method), but I don't think I want a hole in my crank arm.

It'll be a hole about 3/32 of an inch, and will be hidden after you install a new nut & bolt. No
effect on strength or cosmetics. What's the problem?

 

On Sun, 16 Mar 2003, jt <[email protected]> wrote:
>
> "Ian Smith" <[email protected]> wrote in message
> news:[email protected]...
> >
> > From the non-crank side, any drilling into the socket other than down the shaft of the bolt
> > features drilling through some part of the crank spider arm, I think. Certainly, the flange of
> > the socket overlaps the crank arm, because the shaft of the socket is a snug fit within the hole
> > in the crank arm.
>
> That is exactly what you need to do. Drill from the non-crank side, through:
> a) the "bolt" flange
> b) the inner sprocket seating flange
> c) the crank spider
> d) the outer sprocket seating flange
> e) the "nut" flange

Ah, right. I don't think I like that.

> > I can see how it'd work if it was one of teh other sockets and I could drill from the outer face
> > through socket flange into chainring (it's a more sophisticated variant of my grind-a-slot
> > method), but I don't think I want a hole in my crank arm.
>
> It'll be a hole about 3/32 of an inch, and will be hidden after you install a new nut & bolt. No
> effect on strength or cosmetics. What's the problem?

I'm less confident than you that it'll have no effect on strength. It would be in a reasonably
stressed location (adjacent as it is to teh fixings holding teh rings). If I get a perfectly smooth
circular hole it'll probably only concentrate stress by a factor of 3. I expect I'll have some
scoring in the hole so the factor will actually be much higher. Seems to me like a recipe for
triggering a crack which will then fatigue its way to the outer edge of the spider arm.

Of course, if I get to the point where the alternative is throwing away the chainset, a solution
that _might_ result in it breaking some hundreds (thousands? tens of thousands?) of miles down the
road is probably preferable.

I'm now musing with teh idea of gluing a lever to teh head of the nut / socket, so I can apply some
torque. I'm far from convinced it will work, but I don't think it will be pemanently detrimental to
anything if it doesn't. In the meantime, I'm riding on four tight and one loose bolt, and hoping it
will shake loose.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

 

"Ian Smith" <[email protected]> wrote in message news:[email protected]...

[ snip ]

> >
> > It'll be a hole about 3/32 of an inch, and will be hidden after you
install
> > a new nut & bolt. No effect on strength or cosmetics. What's the
problem?
>
> I'm less confident than you that it'll have no effect on strength. It would be in a reasonably
> stressed location (adjacent as it is to teh fixings holding teh rings). If I get a perfectly
> smooth circular hole it'll probably only concentrate stress by a factor of 3. I expect I'll have
> some scoring in the hole so the factor will actually be much higher. Seems to me like a recipe for
> triggering a crack which will then fatigue its way to the outer edge of the spider arm.

Well, I've got one in a TA three-pin crank and have put about 4k miles on
it. No problems so far; I asume you have 5 pins so the stress on yours is proportionally less.
Crank failure is not an issue here; it'll break at the web or the pedal eye first - unless you
have a campy one with the engraved logo - they break in the middle. If it DID start a crack
which went to the edge of the spider arm - well, so what? It would creak, maybe. Won't dump you
on the road.