A problem with gears.

Hi there,

I'm new to this forum, so hello everyone!

I cycle to work on my "Specialized Hard Rock" MTB. It's about 6 miles
each way and I've been doing it since May 2003. Thankfully, all I've had
to replace so far are some spokes -- I haven't even had a puncture yet!

Recently the gears have started acting up: when I'm using the smallest
cog on the cassette the pedals will "jump" about 1/8th of a turn with a
loud clunk. Could this been a problem with the chain or with the
cassette (or both), or something else altogether?

As you can probably tell I'm no expert, so any help would be greatly
appreciated.

Regards,
Donny

Donny wrote:

Recently the gears have started acting up: when I'm using the smallest
cog on the cassette the pedals will "jump" about 1/8th of a turn with a
loud clunk. Could this been a problem with the chain or with the
cassette (or both), or something else altogether?

Could be the gears are out of adjustment and just need a bijou tweakette
of the cable tension. There's a threaded adjuster where the cable goes
into the gear mech at the back, try undoing it a quarter turn and see if
it makes any difference, if not try another quarter turn and so on. If
this /isn't/ the problem then eventually all your other gears will get
out of sync, so just return it to where it was to start with if this
happens (so keep a note of how many quarter turns you did!)

If it isn't that it's quite possibly a worn sprocket, though it's quite
unusual for the wee one to go unless you're a terrible masher (someone
who relies on higher gears and standing on the pedals more than is good
for them or their bike, if this describes you then try spinning lower
gears at a higher cadence).

Completely unrelated to your question, but if you still have the
off-road tyres on the bike then swapping them for some slicks will make
it quite a bit easier to use on the road.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

Peter Clinch wrote:

Donny wrote:

Recently the gears have started acting up: when I'm using the smallest
cog on the cassette the pedals will "jump" about 1/8th of a turn with a
loud clunk. Could this been a problem with the chain or with the
cassette (or both), or something else altogether?

Could be the gears are out of adjustment and just need a bijou tweakette
of the cable tension. There's a threaded adjuster where the cable goes
into the gear mech at the back, try undoing it a quarter turn and see if
it makes any difference, if not try another quarter turn and so on. If
this /isn't/ the problem then eventually all your other gears will get
out of sync, so just return it to where it was to start with if this
happens (so keep a note of how many quarter turns you did!)

If it isn't that it's quite possibly a worn sprocket, though it's quite
unusual for the wee one to go unless you're a terrible masher (someone
who relies on higher gears and standing on the pedals more than is good
for them or their bike, if this describes you then try spinning lower
gears at a higher cadence).



probably the other way around, a worn chain skipping on the little used
sprockets. About par for the mileage

Or the bike has fallen over causing the dropout & derailleur to bend
inwards
--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

Recently the gears have started acting up: when I'm using the smallest
cog on the cassette the pedals will "jump" about 1/8th of a turn with a
loud clunk. Could this been a problem with the chain or with the
cassette (or both), or something else altogether?

Maybe not enough chain tension or maybe the chain has stretched or
worn badly. You've probably knocked up a fair few miles there. Are you
a heavy rider? Lots of hills on route?

You could try;

1) Make sure there are no stiff links in the chain. Its a tighter bend
with the smaller cog/higher rear gear. Clean/degrease then lubricate
and make sure no stiff links.

2) Making sure the wheel is as far back as possible in the frame
dropouts.

3) Make sure the rear cogs are nicely lined up with the front chainset
and chain. Sometimes this means the wheel doesn't sit quite in the
middle of the frame at the bottom bracket end but instead goes very
slightly to one side or the other.

4) There may be a deraileur screw adjustment near where the deraileur
screws to the frame that can increase chain tension slightly.

5) Replace chain and possibly cassette :-(

6) Try a cheap bodge like removing 2 chain links to increase chain
tension if you can get away with this (i.e. have enough play across
the whole gear range to do this and chain may have slightly stretched
with use).

Peter Clinch wrote:
Donny wrote:

Recently the gears have started acting up: when I'm using the smallest
cog on the cassette the pedals will "jump" about 1/8th of a turn with
a loud clunk. Could this been a problem with the chain or with the
cassette (or both), or something else altogether?


Could be the gears are out of adjustment and just need a bijou tweakette
of the cable tension. There's a threaded adjuster where the cable goes
into the gear mech at the back, try undoing it a quarter turn and see if
it makes any difference, if not try another quarter turn and so on. If
this /isn't/ the problem then eventually all your other gears will get
out of sync, so just return it to where it was to start with if this
happens (so keep a note of how many quarter turns you did!)

The problem used to only happen when it was wet and I tried this method
last time it rained a lot. Unfortunately it didn't help!


If it isn't that it's quite possibly a worn sprocket, though it's quite
unusual for the wee one to go unless you're a terrible masher (someone
who relies on higher gears and standing on the pedals more than is good
for them or their bike, if this describes you then try spinning lower
gears at a higher cadence).

I never stand on the pedals but I do use the highest gear about 90% of
the time.


Completely unrelated to your question, but if you still have the
off-road tyres on the bike then swapping them for some slicks will make
it quite a bit easier to use on the road.

Yeah, I've got 1.75 inch road tyres. I really should have bought a road
bike but it's too late now!


Pete.

Martin Wilson wrote:
Recently the gears have started acting up: when I'm using the smallest
cog on the cassette the pedals will "jump" about 1/8th of a turn with a
loud clunk. Could this been a problem with the chain or with the
cassette (or both), or something else altogether?


Maybe not enough chain tension or maybe the chain has stretched or
worn badly. You've probably knocked up a fair few miles there. Are you
a heavy rider? Lots of hills on route?

In answer to these questions: I've probably done over 4000 miles, I'm
about 14 stone, there aren't really any hills, and I use top gear most
of the time.


You could try;

1) Make sure there are no stiff links in the chain. Its a tighter bend
with the smaller cog/higher rear gear. Clean/degrease then lubricate
and make sure no stiff links.

Sounds like a goer, I'll give this a try.


2) Making sure the wheel is as far back as possible in the frame
dropouts.

What are frame dropouts?


3) Make sure the rear cogs are nicely lined up with the front chainset
and chain. Sometimes this means the wheel doesn't sit quite in the
middle of the frame at the bottom bracket end but instead goes very
slightly to one side or the other.

The largest cog at the front is in line with the second smallest at the
back.


4) There may be a deraileur screw adjustment near where the deraileur
screws to the frame that can increase chain tension slightly.

5) Replace chain and possibly cassette :-(

6) Try a cheap bodge like removing 2 chain links to increase chain
tension if you can get away with this (i.e. have enough play across
the whole gear range to do this and chain may have slightly stretched
with use).

Martin Wilson wrote:

Maybe not enough chain tension or maybe the chain has stretched or
worn badly. You've probably knocked up a fair few miles there. Are
you a heavy rider? Lots of hills on route?

The chain almost certainly has stretched, but this has nothing to do
with the weight of the rider or the amount of hill climbing done.
Stretching is caused by wear at the rollers and is accelerated by
lubricating a dirty chain. The plates of the chain do not themselves
stretch significantly.

1) Make sure there are no stiff links in the chain. Its a tighter
bend with the smaller cog/higher rear gear. Clean/degrease then
lubricate and make sure no stiff links.

Good advice. A stiff link is a possibility. You can generally ease it
by grasping the chain firmly either side of the stiff link and flexing
the chain hard sideways in both directions.

2) Making sure the wheel is as far back as possible in the frame
dropouts.

I'd be very surprised if the OP's bike has horizontal dropouts.

5) Replace chain and possibly cassette :-(

If the chain needs replacing the cassette definitely will. A new chain
on a worn cassette will skip like mad.

6) Try a cheap bodge like removing 2 chain links to increase chain
tension if you can get away with this (i.e. have enough play across
the whole gear range to do this and chain may have slightly stretched
with use).

This is risking damage if the rider selects the big/big combination,
which admittedly he shouldn't do. If the chain has stretched that much
then both it and the cassette need replacing.

--
Dave...

Donny popped their head over the parapet saw what was going on and said

Recently the gears have started acting up: when I'm using the
smallest
cog on the cassette the pedals will "jump" about 1/8th of a turn with
a loud clunk. Could this been a problem with the chain or with the
cassette (or both), or something else altogether?

4,000 miles and never a new chain/cassette, is the small cog worn at
all
(shark finning of the teeth) has the chain stretched? If either of
these
apply maybe it's time to think of new ones .
Alternatively you could try adjusting the rear derralieur cable (Mmm
seems you tried that already) have you laid/dropped the bike down on
the drive side? The actual rear derailleur may be bent in which case no
amount of "adjusting/tweaking" will do any good. One thing if all this
seems correct, are the cones in your rear wheel OK, that too will negate
any "adjusting/tweaking"?
All the above is just some things to think about, I am no chain
expert.

--
yours S

Nihil curo de ista tua stulta superstitione

Donny wrote:

I never stand on the pedals but I do use the highest gear about 90% of
the time.

The sprocket and chain is probably worn out--you've got the classic
symptoms. Replace both the cassette and chain if none of the adjustments
and checks work. The chainrings (sprockets at the front) will be ok with
a new chain, with a bit of luck.

Completely unrelated to your question, but if you still have the
off-road tyres on the bike then swapping them for some slicks will
make it quite a bit easier to use on the road.

Yeah, I've got 1.75 inch road tyres. I really should have bought a
road bike but it's too late now!

Not too late for Schwalbe Jets from www.wiggle.co.uk

~PB

"Pete Biggs" wrote in message
...
Donny wrote:

I never stand on the pedals but I do use the highest gear about 90% of
the time.

The sprocket and chain is probably worn out--you've got the classic
symptoms. Replace both the cassette and chain if none of the adjustments
and checks work. The chainrings (sprockets at the front) will be ok with
a new chain, with a bit of luck.

Completely unrelated to your question, but if you still have the
off-road tyres on the bike then swapping them for some slicks will
make it quite a bit easier to use on the road.

Yeah, I've got 1.75 inch road tyres. I really should have bought a
road bike but it's too late now!

Not too late for Schwalbe Jets from www.wiggle.co.uk

~PB


If you are using top gear a lot there are two obvious things to check. One
is your cadence; it's generally reckonned that the higher cadence you can
sensibly manage the better it is for your knees - I aim for 95 rpm but if
I'm off-form struggle to do 85. The second idea is to look at the cassete
your'e using - especially as like Pete I suspect you need a new one - and
look at getting one with a smaller small sprocket to give you a higher top
gear.

HTH
Julia