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:
parktool.comFAQtchan.shtmlOpen ↗

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]>,

Jacobe Hazzard said:

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.

Just been through this myself, although with fewer
consequences as I spotted what was happening before any
damage. However, having disassembled everything, cleaned,
greased and re-assembled I couldn't find a torque wrench
setting for the crank spindle bolts.

Any suggestions, group?

And yes, I've already tried "tighten carefully until the
thread strips then back off a quarter turn" on a previous
bike, thanks ;-)

- Pete Abingdon

Peter Narramore said:

Just been through this myself, although with fewer
consequences as I spotted what was happening before any
damage. However, having disassembled everything, cleaned,
greased and re-assembled I couldn't find a torque wrench
setting for the crank spindle bolts.

Check manufacturer's instructions/website, then Park Tools
website. Unfortunately, you'll find some wide ranges
suggested so it's difficult to know what's "correct".
Hopefully, guess work + common sense + luck will be alright.

~PB

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:
parktool.comFAQtchan.shtmlOpen ↗

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: htmlhelp.com~nickOpen ↗

Peter Narramore said:

Just been through this myself, although with fewer
consequences as I spotted what was happening before any
damage. However, having disassembled everything, cleaned,
greased and re-assembled I couldn't find a torque wrench
setting for the crank spindle bolts.

The best description I've heard for the crank bolt torque
is "[censored] tight" (copyright Brant Richards of On-One
Bicycles). Its a lot lot more than you think it is and
about the limit of what you can apply with a standard long
allen key..

Tony

In article <[email hidden]>, "Tony Raven"

Quoted message said:

Its a lot lot more than you think it is and about the
limit of what you can apply with a standard long
allen key..

Oh, well that's a slight relief. Admittedly I was using an
adjustable wrench rather than an alln key, but my fears that
I was overtightening were probably unfounded.

- Pete