Chain 'slipping' - cause?

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

Quoted message said:

For a few months now I've found that my chain seems to slip while I'm
in a particular gear. When I say 'slip', I mean that as I'm pedalling
the pedals suddenly lose resistance and seem to slip forward by a few
inches. It's pretty irritating, because if I'm standing up it throws
me off balance (and I'm always afraid I'm going to bash myself on the
saddle).

When my bike went in for its first 1,000 mile service recently I told
the LBS about this and they said they'd fix it. It's not fixed,
though. I noticed it again almost as soon as I got the bike back, and
now it's getting worse (i.e. it happens more often).

Is it obvious from my description of the symptom what the problem is,
please, and what might be necessary to cure it?

Wet fishes,
--
,,
(**)PeeWiglet~~
/ \ / \ pee AT [guessthisbit].co.uk

I'm not sure how old the chain is - tho if 1000 miles must be about 4 weeks?
:-) - but doesn't sound as if
it or chainring / sprockets are old enough to be particularly worn. Possibly
a stiff link in the chain - you'll have to see if one looks to be set at a
funny angle or use your hands and check the links...

Peewiglet said:

For a few months now I've found that my chain seems to slip while I'm
in a particular gear. When I say 'slip', I mean that as I'm pedalling
the pedals suddenly lose resistance and seem to slip forward by a few
inches. It's pretty irritating, because if I'm standing up it throws
me off balance (and I'm always afraid I'm going to bash myself on the
saddle).

[De-lurk]

Had a similar problem on my tandem. The cause was a very slight twist
in the chain. This was cured by very carefully winding the pedals
backwards and watching the chain at one point until the twist was
found. Two pairs of pliers then corrected the twist. Of course,
replacing the chain is an alternative cure.

The bike shop suggested that the twist may have happened by powering
too hard during a gear change at the front end.

On a different subject, hello everyone. Been reading this group for a
couple of weeks. Finally found a subject to which I can contribute!

[Re-lurk... perhaps]

PhilD

--
<><

Peewiglet said:

For a few months now I've found that my chain seems to slip while I'm
in a particular gear. When I say 'slip', I mean that as I'm pedalling
the pedals suddenly lose resistance and seem to slip forward by a few
inches. It's pretty irritating, because if I'm standing up it throws
me off balance (and I'm always afraid I'm going to bash myself on the
saddle).

Does it do this primarily under heavy load?

One particular front gear, one particular back gear, or one particular
combination?

If it's a rear gear, "one particular gear" sounds like worn teeth.
Take a look at that gear - if the teeth are sharks-fin shaped, that
could be the culprit.

Although the conventional wisdom says that rear gears wear faster, I had
chain slippage. I replaced the rear set and the chain, and found it now
started slipping on the front. :-)

Alternatively, if it's under really heavy load (and when you say you
stand it, that suggests you do put it under heavy loads), it could be
the rear gear freewheel ratchet slipping - either because it's worn, or
because there's a lot of crud in there. A hefty dose of WD40 will cure
it temporarily (for a couple of days, that is) but the cure is a new
rear gear set.

Unfortunately, particularly with the heavy load slipping, there's no
really effective way to diagnose these with the bike on a stand; you
can't apply big enough forces.

R.

Quoted message said:

Quoted message said:

freewheel ratchet slipping.....the cure is a new
rear gear set.

Unless it's a cassette, of course. Which it surely will be on a bike
this new?

If it really is the ratchet, it should be replaced under warrantee. But
it probably won't be.

iakobski said:

Quoted message said:

Quoted message said:

freewheel ratchet slipping.....the cure is a new
rear gear set.

Unless it's a cassette, of course. Which it surely will be on a bike
this new?

If it really is the ratchet, it should be replaced under warrantee. But
it probably won't be.

As it's quite new I would think the most probable cause is a stiff
chain link.

--
Dave...

Yes, this sounds the most likely - apart from the "in a particular
gear" comment by the OP. It would be pretty hard, but not impossible,
to wear out a chain and a sproket in 1000 miles.

Is it possible the cause might be that the derailleur is slightly out
of adjustment?

Anyway, what do I know, my derailleur, cassette and free hub are all
safely in a box where they can't get anywhere near my chain.

Many thanks to all for the help with this. I'd assumed it was probably
a simple problem and easy to diagnose, but it's clear that it could be
one of a number of things. Will have to take it back to LBS and
request further investigations.

It only happens in one gear. I'm not sure how to describe them, but
there are 3 'gears' which each have 8 sub-divisions (I know I'm not
putting that right - sorry!). I always have the bike in the 'middle'
gear (i.e. 2 on the left handlebar), and the slipping only occurs when
I have it in the 7th sub-division on the right handlebar. I hope you
can see what I mean!

As for whether it only happens when I exert particular force, I think
I should have been more careful in what I wrote earlier. It happens
both when I'm sitting and standing - more often while I'm sitting,
actually, as I'm rarely standing - but I particularly dislike it when
I'm standing as I'm always afraid my sensitive bits will come down
hard on the pointy bit of the saddle <wince>. I don't really have to
be pedalling particularly hard for it to happen.

A bit of further info is that when I first mentioned it at the LBS the
bike was on about 800 miles, and the chappie took a look at the chain
(or the cogs - something down there, anyway). He said something about
a bit of wear in that particular gear, but expressed some surprise as
he has the same bike and has done 3000 miles, and he's not got the
same wear yet. I realise I don't know what I'm talking about here, but
I hope that it might make some sense to someone out there! Anyway, he
said to leave it until the bike got to 1000 miles (a few weeks later)
and they'd sort it on the service. I reminded them, but it's not
sorted. I thought it was for the first half an hour, but then it
happened again. It now happens with increasing frequency, although
it's not quite as frequent as it had become immediately pre service,
by which stage it was such a nuisnance that I was virtually unable to
ride in gear 2/7.

Well, I hope this makes some sense and adds a bit of further context!

Thanks again for your help 🙂

Wet fishes,
--
,,
(**)PeeWiglet~~
/ \ / \ pee AT [guessthisbit].co.uk

Peewiglet said:

Many thanks to all for the help with this. I'd assumed it was probably
a simple problem and easy to diagnose, but it's clear that it could be
one of a number of things. Will have to take it back to LBS and
request further investigations.

It only happens in one gear. I'm not sure how to describe them, but
there are 3 'gears' which each have 8 sub-divisions (I know I'm not
putting that right - sorry!). I always have the bike in the 'middle'
gear (i.e. 2 on the left handlebar), and the slipping only occurs when
I have it in the 7th sub-division on the right handlebar. I hope you
can see what I mean!

As for whether it only happens when I exert particular force, I think
I should have been more careful in what I wrote earlier. It happens
both when I'm sitting and standing - more often while I'm sitting,
actually, as I'm rarely standing - but I particularly dislike it when
I'm standing as I'm always afraid my sensitive bits will come down
hard on the pointy bit of the saddle <wince>. I don't really have to
be pedalling particularly hard for it to happen.

You have three chainrings at the front and eight sprockets at the
back. The chainrings are controlled from the LH changer and the
sprockets from the RH one. The chainrings are usually called outer
middle and inner. The sprockets are called by number form the one
nearest the spokes one to eight, hence one is the biggest and eight is
the smallest.

You say the chain is jumping in middle and seventh is that seventh or
second? In any case try the chain on outer or inner on seventh to see
if it jumps in that combination.

If it is that particular sprocket that is causing it to jump it may be
possible to replace just that sprocket (since the cassette is
relatively new) or if that isn't possible a new cassette should cure
it if it isn't a stiff link in the chain. But I don't think its a
stiff link because it would jump in other gears if it was.
--
Phil Cook looking north over the park to the "Westminster Gasworks"

Phil Cook said:

Peewiglet said:

Many thanks to all for the help with this. I'd assumed it was probably
a simple problem and easy to diagnose, but it's clear that it could be
one of a number of things. Will have to take it back to LBS and
request further investigations.

It only happens in one gear. I'm not sure how to describe them, but
there are 3 'gears' which each have 8 sub-divisions (I know I'm not
putting that right - sorry!). I always have the bike in the 'middle'
gear (i.e. 2 on the left handlebar), and the slipping only occurs when
I have it in the 7th sub-division on the right handlebar. I hope you
can see what I mean!

As for whether it only happens when I exert particular force, I think
I should have been more careful in what I wrote earlier. It happens
both when I'm sitting and standing - more often while I'm sitting,
actually, as I'm rarely standing - but I particularly dislike it when
I'm standing as I'm always afraid my sensitive bits will come down
hard on the pointy bit of the saddle <wince>. I don't really have to
be pedalling particularly hard for it to happen.

Hi Phil,

Quoted message said:

You have three chainrings at the front and eight sprockets at the
back. The chainrings are controlled from the LH changer and the
sprockets from the RH one. The chainrings are usually called outer
middle and inner. The sprockets are called by number form the one
nearest the spokes one to eight, hence one is the biggest and eight is
the smallest.

You say the chain is jumping in middle and seventh is that seventh or
second?

7th i.e. the second hardest 'gear' on the second chainring. (7th is
what it says on the handlebar gearshifter, anyway.)

Quoted message said:

In any case try the chain on outer or inner on seventh to see
if it jumps in that combination.

Will do - thanks for the tip. Will report back 🙂

Quoted message said:

If it is that particular sprocket that is causing it to jump it may be
possible to replace just that sprocket (since the cassette is
relatively new) or if that isn't possible a new cassette should cure
it if it isn't a stiff link in the chain. But I don't think its a
stiff link because it would jump in other gears if it was.

If it's a sprocket problem, is that likely to be an expensive fix?

Wet fishes,
--
,,
(**)PeeWiglet~~
/ \ / \ pee AT [guessthisbit].co.uk

Peewiglet said:

On Thu, 17 Nov 2005 14:48:29 +0000, Phil Cook
<[email hidden]> wrote:

Quoted message said:

7th i.e. the second hardest 'gear' on the second chainring. (7th is
what it says on the handlebar gearshifter, anyway.)

Ah, that makes it easy doesn't it :-)

Quoted message said:

Quoted message said:

In any case try the chain on outer or inner on seventh to see
if it jumps in that combination.

Will do - thanks for the tip. Will report back 🙂

Quoted message said:

If it is that particular sprocket that is causing it to jump it may be
possible to replace just that sprocket (since the cassette is
relatively new) or if that isn't possible a new cassette should cure
it if it isn't a stiff link in the chain. But I don't think its a
stiff link because it would jump in other gears if it was.

If it's a sprocket problem, is that likely to be an expensive fix?

Cassettes are from about 15 quid sprockets from 6 on
http://www.sjscycles.com.

LBS prices may differ. But since it's a new bike try and get them to
replace it under warranty.

You've just reminded me to go and look at my gears. I'm getting clunks
and mis-shifts. I suspect they just out of adjustment which could also
be the cause of your problems.

For ajdustment and service instructions see here (long URL may wrap)
http://www.shimano.com.au/publish/content/australia/en/cycling/customer_support/service_diagrams/mtb_2005.MainContentPar.0023.Schematic.0002.File.tmp/SI-6JXRA-En.pdf

--
Phil Cook - fully paid up member of the black hand gang, with oily
smudges on his carpet.

Quoted message said:

The bike shop suggested that the twist may have happened by powering
too hard during a gear change at the front end.

I think that twist can also occur by being in the highest sprocket
gear and lowest chainring, or lowest sprocket and highest chainring.

On a 21 gear bike, used gears should be something like this:

Chainring 1 Sprocket 1, 2, 3, 4
Chainring 2 Sprocket 2, 3, 4, 5, 6
Chainring 3 Sprocket 4, 5, 6, 7

Giving just 13 used gears.

Quoted message said:

On a different subject, hello everyone. Been reading this group for a
couple of weeks. Finally found a subject to which I can contribute!

Your post is very welcome.

On Thu, 17 Nov 2005 17:19:09 +0000, Bertie Wiggins
<[email hidden]> wrote:

<snip>

Quoted message said:

On a 21 gear bike, used gears should be something like this:

Chainring 1 Sprocket 1, 2, 3, 4
Chainring 2 Sprocket 2, 3, 4, 5, 6
Chainring 3 Sprocket 4, 5, 6, 7

Giving just 13 used gears.

Thou jesteth, surely ? I have a recently-built winter / Audax (the
bkurb says) bike, with Campy 10 x 3 (i.e. 30 speed). I reckon 28 are
usable - Not 52 x 23, or 30 x 14, but all others.

Tony - in hilly Norfolk

Tony said:

On Thu, 17 Nov 2005 17:19:09 +0000, Bertie Wiggins
<[email hidden]> wrote:

<snip>

Quoted message said:

On a 21 gear bike, used gears should be something like this:

Chainring 1 Sprocket 1, 2, 3, 4
Chainring 2 Sprocket 2, 3, 4, 5, 6
Chainring 3 Sprocket 4, 5, 6, 7

Giving just 13 used gears.

Thou jesteth, surely ? I have a recently-built winter / Audax (the
bkurb says) bike, with Campy 10 x 3 (i.e. 30 speed). I reckon 28 are
usable - Not 52 x 23, or 30 x 14, but all others.

My boring opinion is that somewhere in between what you two are suggesting
is reasonable. It's not a binary thing -- that gears are either good or
bad -- just that the more crossed over the chain is, the more inefficient
it is and the more wear it causes. You /can/ use the poorer combinations
but use them more sparingly and not with maximum torque.

I have Campag triple 9-speed and certainly big ring with second largest
rear sprocket, for example, is too crossed-over for my liking. I can feel
the friction through my feet. Middle ring to largest sprocket isn't great
either but I do use it briefly.

~PB

On Sun, 27 Nov 2005 17:03:31 +0000 (UTC), Tony <[email hidden]>

Quoted message said:

On Thu, 17 Nov 2005 17:19:09 +0000, Bertie Wiggins
<[email hidden]> wrote:

<snip>

Quoted message said:

On a 21 gear bike, used gears should be something like this:

Chainring 1 Sprocket 1, 2, 3, 4
Chainring 2 Sprocket 2, 3, 4, 5, 6
Chainring 3 Sprocket 4, 5, 6, 7

Giving just 13 used gears.

Thou jesteth, surely ? I have a recently-built winter / Audax (the
bkurb says) bike, with Campy 10 x 3 (i.e. 30 speed). I reckon 28 are
usable - Not 52 x 23, or 30 x 14, but all others.

Assuming:
Chainset 52, 42, 30
Sprocket set 14, 15, 16, 17, 18, 19, 20, 21, 22, 23

Gear Ratios
Gear 1 1.30
Gear 2 1.36
Gear 3 1.43
Gear 4 1.50
Gear 5 1.58
Gear 6 1.67
Gear 7 1.76
Gear 8 1.88
Gear 9 2.00
Gear 10 2.14
Gear 11 1.83
Gear 12 1.91
Gear 13 2.00
Gear 14 2.10
Gear 15 2.21
Gear 16 2.33
Gear 17 2.47
Gear 18 2.63
Gear 19 2.80
Gear 20 3.00
Gear 21 2.26
Gear 22 2.36
Gear 23 2.48
Gear 24 2.60
Gear 25 2.74
Gear 26 2.89
Gear 27 3.06
Gear 28 3.25
Gear 29 3.46
Gear 30 3.72

Gears without overlap are: 1, 2, 3, 4, 5, 6, 7, 8, 13, 14, 15, 16, 17,
24, 25, 26, 27, 28, 29, 30

The useful gears are:
Chainring 30, sprocket 23, 22, 21, 20, 19, 18, 17, 16
Chainring 42, sprocket 21, 20, 19, 18, 17
Chainring 52, sprocket 20, 19, 18, 17, 16, 15, 14

The range is 286%.

My 44/15 Rohloff gives me:
Gear 1 0.82
Gear 2 0.93
Gear 3 1.06
Gear 4 1.20
Gear 5 1.36
Gear 6 1.55
Gear 7 1.76
Gear 8 2.00
Gear 9 2.27
Gear 10 2.58
Gear 11 2.93
Gear 12 3.33
Gear 13 3.79
Gear 14 4.30

Gears are evenly spaced at 13.6%, giving a range of 524%