Stiff links and loose brackets

Nick Kew said:

(1) What is supposed to prevent the chainset drifting out, and how
dows it fail in such a potentially-catastrophic manner?

correct assembly will seldom, if ever, lead to failure.

Quoted message said:

(2) Are the stiff links down to the chain, the chain tool, or a
mismatch between them, and is there anything I can do? I have
fixed chains before without any such problem.

you don't say which type of chain, but the fact that you're riveting
rather than using a link connector indicates shimano. all you need to
do is CAREFULLY re-space the rivet using the chain tool's "second" set
of leverage points, [the ones nearest the screw] and you're done. no
pinch. you chain tool almost certainly carries appropriate instructions
for use.

Quoted message said:

(3) AFAICS the most likely way to fix link stiffness is to force-loosen
the outer bit at the stiff link. Could that be what the bike
shop did that caused the chain to break?

not if it was done right.

sounds like this whole job was badly messed up. use the tool as
described in the instructions, AND, if using shimano chain, use the
supplied special replacement rivets on any break. buy more if
necessary. DO NOT attempt re-use of old rivets under any circumstances.

"Nick Kew" <[email hidden]> wrote

Quoted message said:

(1) What is supposed to prevent the chainset drifting out, and how
dows it fail in such a potentially-catastrophic manner?

It wasn't tightened enough.

Quoted message said:

(2) Are the stiff links down to the chain, the chain tool, or a
mismatch between them, and is there anything I can do? I have
fixed chains before without any such problem.
(3) AFAICS the most likely way to fix link stiffness is to force-loosen
the outer bit at the stiff link. Could that be what the bike
shop did that caused the chain to break?

Perhaps. When riveting chains you need to be very careful to make sure that
just the right amount of rivet protrudes from each side plate. Often, chain
tools will have an extra position for loosening a tight link. Wiggling
side-to-side also will loosen. Most chain breaks come from bad joins, it takes
a bit of care and experience to get a reliable join. Quick-links are a better
solution for most people. SRAM chains come with one, so you just have to
shorten the chain to the right length for your bike with a tool, then snap the
quick-link together. Quick-links can also be bought a la cart.

Nick Kew said:

(2) Are the stiff links down to the chain, the chain tool, or a
mismatch between them, and is there anything I can do? I have
fixed chains before without any such problem.

It's difficult to avoid a stiff link at first when joing most modern
chains, but they can be freed properly, see:
http://www.parktool.com/repair_help/FAQtchan.shtml

The whole job is easier with some tools than others. Rust or total lack
of lubrication can also cause stiff links.

Quoted message said:

(3) AFAICS the most likely way to fix link stiffness is to
force-loosen the outer bit at the stiff link. Could that be what
the bike shop did that caused the chain to break?

Possibly.

~PB

Nick Kew said:

(1) Unable to select the largest chainring. And very shortly afterwards
struggling to select the middle chainring. The problem turned out to be
that the right pedal + chainrings were unscrewing from the bottom
bracket, and had moved far enough to put the chain out of alignment.

The crank wasn't tightened onto the BB spindle enough. Riding the bike
with a loose crank can damage the crank so that it will need to be
replaced. Best to remove the crank, grease the interface properly, and
torque on the spindle bolt properly, hoping the taper of the crank is
still good.

Nick Kew said:

After a winter on an extremely knackered drive chain, I recently had it
replaced, when it had become clear that the threat of salted roads had
receded for the season. The whole caboodle: chainset, rear gears, and
chain. The bike is a mid-1990s mid-range MTB, with a conventional
18-gear configuration.

At first, all was well, except for a left pedal that doesn't run well and
also needs replacing. But very soon I had trouble:

(1) Unable to select the largest chainring. And very shortly afterwards
struggling to select the middle chainring. The problem turned out to be
that the right pedal + chainrings were unscrewing from the bottom bracket,
and had moved far enough to put the chain out of alignment.

(2) The (new) chain had developed a kink and was clunking. I don't know
if there had always been a minor problem - it's possible that there had
but that I'd attributed it to the clunky left pedal. When it broke,
it was clearly a visibly-bent link,

That's two problems with work by an LBS I had previously thought good.
I didn't do it myself, because I know very well that I'm no mechanic,
but I'm an expert when it comes to mislaying expensive tools necessary
for such jobs. So when the chain broke, it was no surprise to find
I'd lost the chain tool, making it an annoyingly long (6 mile) walk
- which I haven't yet found time for - to get to the b***** bike shop.

Yesterday I took the (twice-weekly) bus to Tescos, and got a new
chain tool from a motor-spares shop next door to them. Today I
tried to fix the bike. I was able to screw the loose assembly back
in sufficiently to venture out on the six miles to the shop. But
the chain defeated me: any link I assembled with the chain tool proved
stiff as hell, and there seems to be nothing I can do with that.

So my questions:

(1) What is supposed to prevent the chainset drifting out, and how
dows it fail in such a potentially-catastrophic manner?
(2) Are the stiff links down to the chain, the chain tool, or a
mismatch between them, and is there anything I can do? I have
fixed chains before without any such problem.
(3) AFAICS the most likely way to fix link stiffness is to force-loosen
the outer bit at the stiff link. Could that be what the bike
shop did that caused the chain to break?

I think you are saying the crank bearing assembly is
unscrewing from the bike. It's supposed to be tight in the
frame and, yes, your LBS should do that over.

Did you toss the directions from the chain riveter? That
makes you a normal cyclist!

There are two plates on the top of the tool.

To drive out a rivet, place the chain on the heavy plate
farthest from the screw. Oil the screw. Turn until the
rivet is not quite flush with the inside of the far plate,
that is, don't press the rivet all the way out. You may
wiggle the chain apart even with the rivet protruding
slightly into the inner plate by flexing the chain sideways.

To reinstall a rivet, flip the chain over on the farthest
plate of the tool. Ensure it is all the way down in the slot
so the screw's pin lines up with the rivet perfectly. Now
press the rivet back through until it sticks out exactly as
much as the rivets on either side. Use your fingers to feel
that.

Now the link will be tight because you pressed the plates
against each other while driving the rivet.

Turn the chain over and drop it on the small plate closest
to the screw. Turn the screw against the rivet ever so
gently so as to press the link apart slightly, just until it
moves freely.

Again, feel the rivets and ensure they are all the same height.

Even when used carefully, a chain tool may be insufficient
for some modern chain . That's why we have snaplinks now.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

In article <[email hidden]>,

Pete Biggs said:

It's difficult to avoid a stiff link at first when joing most modern
chains, but they can be freed properly, see:
http://www.parktool.com/repair_help/FAQtchan.shtml

Ah, that was helpful. The new chaintool (unlike the old/lost one)
is too useless to have the position needed for that, but I've applied
a good deal of lateral force with my hands, as suggested there, and
got a big improvement.

Quoted message said:

The whole job is easier with some tools than others. Rust or total lack
of lubrication can also cause stiff links.

Heh! This is a new chain with a two-figure mileage!

Thanks to everyone who replied:-) I'm still going to take it back
to the bike shop and have words - and get them to fix the braket
properly - but at least it's now good for the six miles to get there.

--
Nick Kew

Nick's manifesto: http://www.htmlhelp.com/~nick/