How do you determine that a chainring is worn out?
Ralph Barone
1) If you get chainsuck and end up in a tangled heap on the road, your
chainring may be worn out.
2) If you replace the chain and it doesn't fit properly on the
chainring, your chainring may be worn out.
3) If it's so far gone that you can see the asymmetrical wear and the
"shark fin" profile, your chainring may be worn out.
Does anyone have advice on diagnosing less obvious cases, without using
a new chain as a measuring gauge?
DougC
There really isn't any way that is cheaper and easier than just using a
piece of new/unused chain that is long enough to wrap completely around
the ring.
-And really, going all the way around is overkill. The chain only needs
to wrap halfway around the chainring, in actual use. If it can do that
without buckling and you get no other symptoms like skipping under hard
pedaling, then forget about it. It's still good.
Brian Huntley
> 3) If it's so far gone that you can see the asymmetrical wear and the
> "shark fin" profile, your chainring may be worn out.
I run on my "big" ring (44t) most of the time around town and even on
tour (1 week per year.) I ride a minimum of 5000km a year, though
sometimes hit 8-10,000. That said, I decided to ride 2 chains and one
set of sprockets and chainwheels on my bike until it all wore out, and
it lasted 5 years. That's on 8-speed Shimano LX gear with barcons that
were in friction mode four at least 3 of those years.
The 44t ring could have been used on a power saw when it was done! It
was actually sharp to the touch.
The cranks were still in good shape so I only replaced the one ring
(and the cassette, and both chains.) Sadly, I don' t think my current
setup will last as long, but it won't be the chainrings' fault.
Ciera
> Does anyone have advice on diagnosing less obvious cases, without using
> a new chain as a measuring gauge?
I'm interested in various answers to this question, too. (Doug' answer
is a good one.)
The first time I bought a ramped and pinned crankset I thought they
had sent me a defective one. It had short, medium and full length
teeth and not all teeth were symmetric like old school chainwheels.
Looked like a drunken machinist had taken a crankset and ground it
down in a fit of anger.
An obviously worn out chainring is not hard to judge, but how do you
know when things are just starting to go from good to bad?
Ciera
thirty-six
The chain slips when you're giving it your all on the chaingang or up
the local steep hill. But it's not dead yey, still suitable for
single sprockit setup.
landotter
Does it shift funny? Or skip under load? Yes? Does it look a little
sharky? Replace it.
DougC
> On May 7, 10:43 pm, Ralph Barone<invalid@not_real.ca> wrote:
>> Does anyone have advice on diagnosing less obvious cases, without using
>> a new chain as a measuring gauge?
>
> I'm interested in various answers to this question, too. (Doug' answer
> is a good one.)
>
>
> know when things are just starting to go from good to bad?
>
Ummm,,,,, the bike skips under hard pedaling?
The chain is the main test that's useful, since it's the part that the
chainring teeth need to work properly in.
I suppose if you wanted to be absolutely certain, you could try wrapping
the chain around all the different chainrings and cogs separately to see
how it fit to all of them. If you used one or a couple gear combinations
a lot more than the others, those rings/cogs might get worn first--so
that the worn chain worked well on the worn rings/cogs, but not well on
the un-worn ones.
Also We Note: to an extent, the chain and cogs/rings wear down equally
so that they still work fine together--but if you try to mount a new
chain, it can display functional problems on the worn rings.
--------
If the chain appeared normal visually and the bike functioned properly,
why would you suspect that the chain needed replacing at all?
If you're worried about broken links or ejecting pins, that's usually
caused by the chain being damaged physically (such as being twisted in a
wreck).
Mike Jacoubowsky
news:xMvxp.27313$vC5....@newsfe01.iad...
You can tell a worn chain by wrapping it around a chainring, but curious
what you're seeing when you wrap a new chain around a worn chainring. As
a chain wears, it actually changes pitch, which is what keeps it from
settling properly onto a chainring (since the pitch no longer matches).
The pitch on a worn chainring remains constant though. You can certainly
detect sloppiness in the fit by the amount the chain can be rotated back
& forth on the chainring, but it's nowhere near as obvious as the effect
of a change in chain pitch. I have seen a few chainrings so badly worn
that they had developed hooks that did in fact snag the chain. Those you
could test for in this manner, but you don't have to, since they're
visually impressive.
Middle chainrings on 9 & 10-speed road bikes are where we often see
chainrings worn so badly that they chain will skip on them, with
lifespans running from 5,000 to 15,000 miles, depending upon how well
the drivetrain is maintained. Prior to STI's pins & ramps, chainring
life was considerably longer.
--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com, then forget about it. It's still good.
Ralph Barone
DougC <dci...@norcom2000.com> wrote:
Let me 'splain some more about my situation. I bought a used bike for
the mother in law. It's the right size for her (5' 0"), but for me,
it's like a clown on a tricycle, so jumping on and riding it hard isn't
really going to work for me. The chain measures out at around 5%
elongation, I can see that some gears on the rear cluster have
asymmetrical profiles and the chain is a bit floppy on the front
chainrings.
I could give it to her as is, but the thought of a 70 year old lady
taking a header when the chain sucks into the front chainring isn't very
appealing.
I will probably replace the chain, and possibly the rear cluster, but by
the time I add in new chainrings on the front, I may as well just ditch
the thing and buy a new bike. Therefore, I am looking for a way to
assess the front chainrings that doesn't involve buying a new chain
first.
James
Unless your 70 year old mother in law is very strong or very heavy, I
doubt there will be a problem.
Can you pull the chain forward off the chain ring and clear the height
of a tooth?
Even at this stage, it takes some effort to cause a chain to skip or suck.
The tooth profile would need to be very bad for chain suck to be an
issue, and then you could always run a file over the back of the teeth
to remove the hook.
If you can't make it skip or play up while standing on the pedals and
going hard off the line, go in peace and be happy!
JS.
DougC
Did she want external gears?
Most older people seem to find external-gears difficult to use,
particularly if they're just casual riders anyway.
I would suggest you junk the exernal gears totally and put on an
internal-gear 7- or 8-speed drivetrain with a modest (40t) sprocket
instead.
Yes IGH costs more, but a bicycle that doesn't get used isn't very cheap
either and won't make either of you happy. If she asks what it cost, lie.
Ralph Barone
DougC <dci...@norcom2000.com> wrote:
I'm already lying about what it cost :-)
AMuzi
What bicycle is this? As Mike noted, thin 9~10~11 speed
rings do wear pretty darned quickly and obviously so by eye.
If you have a midprice 3x7 setup from the 1980s that's
unlikely to be a problem.
Replace chain and freewheel (or cassette) and check for
straight wheels, no lumps in the tires, functional braking
system, handlebar secured, etc.
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
Ralph Barone
wrote:
The bike is a Giant Cypress W (most likely a 2009, but I'm not perfectly
sure) with Shimano 3x7 gears. It was purchased from a rental place, so
it's been ridden a lot, but probably not very hard. At first glance, it
looked to be in pretty good shape. Tires are new, wheels are straight
and round, brakes work well, all adjustments work and are tight. So
far, it just seems to be the chain and the rear gears that appear to
need replacement.
AMuzi
Agreed, change the chain and cassette and worry not.
kolldata
the Coors brewery. River and Pillar AAA
kolldata
the look is unmechancial, replace it. When replacing CR then replace
chain and cassette right ? and BB why not ?