A problem with gears.

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

Quoted message said:

James Annan said:

Pete Biggs said:

> It is, in my opinion, undoubtedly dirt which is the main factor in
>bicycle chain wear.

I'm not totally convinced it's the main factor. Might be, but the

issue

Quoted message said:

Quoted message said:

Quoted message said:

seems far from clear to me as there are so many factors.

You've just had it demonstrated to you why dirt must the main factor:
compare the stress of a loaded tandem riding big hills in clean dry
roads, to an MTB in muddy areas.

James

Take a look at the clydesdale forum over on mtbr.com and you'll find
riders who have destroyed their gearing in one day because of the
torque they have put into their gearing. There's also reports of
excessive chain wear over normal weight riders. I can't believe anyone
would be surprised by this. Personally I think your not firing on all
cyclinders if you think load isn't a factor with regard chain and
cassette wear even if its not the main factor but hopefully if you
read some real world experiences you might think differently.

How about having some real world experience, not just reading it? Remember,
James is talking about tandems, which means twice the force.

Then check out the results for tandem riders giving clean chains a very hard
time - there are people out there who are doing so and not getting
significant wear.

Now destroying gearing is a different matter - folding cassettes (we won't
use the shimano ones with the spider any more - they're not strong enough)
and stripping freewheels (shimano free hubs aren't strong enough for MTB
tandem use) are typical modes of failure - and have both happened to us. But
that's breaking things, not wearing them out.

cheers,
clive

in message <[email hidden]>, Martin Wilson

(') said:

James Annan said:

Pete Biggs wrote:

Quoted message said:

Quoted message said:

I'm not totally convinced it's the main factor.  Might be, but the
issue seems far from clear to me as there are so many factors.

You've just had it demonstrated to you why dirt must the main factor:
compare the stress of a loaded tandem riding big hills in clean dry
roads, to an MTB in muddy areas.

Take a look at the clydesdale forum over on mtbr.com and you'll find
riders who have destroyed their gearing in one day because of the
torque they have put into their gearing. There's also reports of
excessive chain wear over normal weight riders. I can't believe anyone
would be surprised by this. Personally I think your not firing on all
cyclinders if you think load isn't a factor with regard chain and
cassette wear even if its not the main factor but hopefully if you
read some real world experiences you might think differently.

Clearly stress on the transmission has to be an issue. However, as
another datapoint, I have a friend who is a time trialist who weighs
about sixteen stone and habitually uses 180mm cranks, a 60 tooth
chainring, and a relatively slow cadence. And wins. The stress he puts
into his transmission (Campag ten speed) makes me cringe. Yet he
doesn't complain of transmission wear (he does, unsurprisingly,
complain about his knees).

A well maintained, reasonable quality, clean bicycle transmission seems
to me to last a reasonably long time. Certainly my own mountain bike
chains wear out much faster than my road bike chains, with similar
levels of power input and similar maintenance.

So I still hold to my opinion that dirt is at least _a_ major issue and
probably _the_ major issue in transmission wear.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/
"This young man has not the faintest idea how socialists think and does
not begin to understand the mentality of the party he has been elected
to lead. He is quite simply a liberal"
-- Ken Coates MEP (Lab) of Tony Blair

Martin Wilson said:

Personally I think your not firing on all
cyclinders if you think load isn't a factor with regard chain and
cassette wear even if its not the main factor but hopefully if you
read some real world experiences you might think differently.

Personally I think you're not firing on all cyclinders if you prefer to
make up some feeble straw man rather than just read what I said, which
was neither ambiguous nor inaccurate.

James
--
If I have seen further than others, it is
by treading on the toes of giants.
http://www.ne.jp/asahi/julesandjames/home/

James Annan said:

You've just had it demonstrated to you why dirt must the main factor:
compare the stress of a loaded tandem riding big hills in clean dry
roads, to an MTB in muddy areas.

Do the tandems have the same gears as the MTB's, or do they have larger
cogs? The chain has to rotate more on smaller sprockets, causing more
wear.

I don't know how the stresses compare anyway. Serious off-roaders apply
serious amounts of torque.

Not convinvced it's mostly down to dirt yet,

~PB

Pete Biggs said:

Do the tandems have the same gears as the MTB's, or do they have
larger cogs? The chain has to rotate more on smaller sprockets,
causing more wear.

No, the chain rotates more with larger sprockets. Imagine a 30-tooth
chainring with a 15-tooth sprocket. For each complete rotation of the
cranks the chain advances 30 links. Now think of a 60-tooth chainring
with a 30-tooth sprocket. The gearing is the same but the chain is
advancing at twice the rate - 60 links per crank revolution. The chain
tension, however, is greater with the smaller chainring and sprocket.
--
Dave...

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

Quoted message said:

James Annan said:

You've just had it demonstrated to you why dirt must the main factor:
compare the stress of a loaded tandem riding big hills in clean dry
roads, to an MTB in muddy areas.

Do the tandems have the same gears as the MTB's, or do they have larger
cogs? The chain has to rotate more on smaller sprockets, causing more
wear.

Tandems tend to have the same on the back, and bigger high gears on the
front. Eg we have 11-32/34 and 24/38/50.

Quoted message said:

I don't know how the stresses compare anyway. Serious off-roaders apply
serious amounts of torque.

And not-so-serious off-road tandem teams apply even more serious amounts of
torque.

cheers,
clive

soup said:

[snippage]

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 .

The small cog definitely has some teeth that look more shark-finny than
the others; I reckon I need to replace it.

The two smallest cogs on the cassette are separate from the rest so
hopefully I could just buy replacements for these?

I guess I'll need a new chain as well?

Cheers,
Donny

dkahn400 said:

Pete Biggs said:

Do the tandems have the same gears as the MTB's, or do they have
larger cogs? The chain has to rotate more on smaller sprockets,
causing more wear.

No, the chain rotates more with larger sprockets. Imagine a 30-tooth
chainring with a 15-tooth sprocket. For each complete rotation of the
cranks the chain advances 30 links. Now think of a 60-tooth chainring
with a 30-tooth sprocket. The gearing is the same but the chain is
advancing at twice the rate - 60 links per crank revolution. The chain
tension, however, is greater with the smaller chainring and sprocket.

Chain links rotate more with smaller sprockets as they conform to the
sprockets. Friction within the chain from this factor is highly
significant. Tests have proved that larger sprockets are more efficient.

~PB

Clive George said:

Quoted message said:

Do the tandems have the same gears as the MTB's, or do they have
larger cogs? The chain [links have] to rotate more on smaller

sprockets,

Quoted message said:

Quoted message said:

causing more wear.

Tandems tend to have the same on the back, and bigger high gears on
the front. Eg we have 11-32/34 and 24/38/50.

A combination that causes less wear.

~PB
(edit in square brackets)

dkahn400 said:

Pete Biggs said:

Do the tandems have the same gears as the MTB's, or do they have
larger cogs? The chain has to rotate more on smaller sprockets,
causing more wear.

No, the chain rotates more with larger sprockets. Imagine a 30-tooth
chainring with a 15-tooth sprocket. For each complete rotation of the
cranks the chain advances 30 links. Now think of a 60-tooth chainring
with a 30-tooth sprocket. The gearing is the same but the chain is
advancing at twice the rate - 60 links per crank revolution. The chain
tension, however, is greater with the smaller chainring and sprocket.

take two:

It's not particularly important how many links are contacting the
sprockets. More relevant is friction within the chain, which in turn
causes sprocket wear as the chain elongates. Chains wear themselves out
more rapidly when they are forced to conform to smaller sprockets. I
believe this factor more than makes up for the difference in number of
teeth that the chain is contacting.

Nb. I include chainrings with "sprockets".

~PB

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

Quoted message said:

Clive George said:

Quoted message said:

Do the tandems have the same gears as the MTB's, or do they have
larger cogs? The chain [links have] to rotate more on smaller

sprockets,

Quoted message said:

Quoted message said:

causing more wear.

Tandems tend to have the same on the back, and bigger high gears on
the front. Eg we have 11-32/34 and 24/38/50.

A combination that causes less wear.

Not convinced - both end up using the 11t, which is where the worst rotation
is.

cheers,
clive

Clive George said:

Quoted message said:

Quoted message said:

> Do the tandems have the same gears as the MTB's, or do they have
> larger cogs? The chain [links have] to rotate more on smaller
> sprockets, causing more wear.

Tandems tend to have the same on the back, and bigger high gears on
the front. Eg we have 11-32/34 and 24/38/50.

A combination that causes less wear.

Not convinced - both end up using the 11t, which is where the worst
rotation is.

Agreed the worst rotation is at the 11t but a smaller chainring causes
more rotation still, hence more wear.

~PB

Pete Biggs said:

Chain links rotate more with smaller sprockets as they conform to
the sprockets. Friction within the chain from this factor is
highly significant. Tests have proved that larger sprockets are
more efficient.

OIC. You mean the rotation of the link itself as it passes over the
sprocket. I thought you were referring to rotations of the complete
chain.

--
Dave...

dkahn400 said:

OIC. You mean the rotation of the link itself as it passes over the
sprocket. I thought you were referring to rotations of the complete
chain.

That's right, sorry I didn't make it clearer. It's the kind of thing I
find difficult to put into words, but that doesn't stop me being
interested in the subject :-)

~PB

Pete Biggs said:

James Annan said:

You've just had it demonstrated to you why dirt must the main factor:
compare the stress of a loaded tandem riding big hills in clean dry
roads, to an MTB in muddy areas.

Do the tandems have the same gears as the MTB's, or do they have larger
cogs? The chain has to rotate more on smaller sprockets, causing more
wear.

Basically the same, although there is certainly a tendency to smaller
granny rings for touring and hills. 18T is not unheard-of. We also like
a large big ring for flat roads, but that is not really relevant to the
discussion.

Quoted message said:

I don't know how the stresses compare anyway. Serious off-roaders apply
serious amounts of torque.

Actually, most of whon you are considering as "serious off-roaders" are
probably skinny midgets who exert rather low forces and use unusually
high gears. A pair of lardy yanks carrying a tent hauling ass up a hill
in their granny gear, now THAT is a serious amount of torque, even
though they are going at walking speed!

Quoted message said:

Not convinvced it's mostly down to dirt yet,

Nevertheless, it is. Obviously load will also have some effect too, but
it can not explain the order-of-magnitude (and more) differences in wear
that are routinely found between clean and dirty use.

James
--
If I have seen further than others, it is
by treading on the toes of giants.
http://www.ne.jp/asahi/julesandjames/home/

Quoted message said:

The small cog definitely has some teeth that look more shark-finny than
the others; I reckon I need to replace it.

The two smallest cogs on the cassette are separate from the rest so
hopefully I could just buy replacements for these?

Hopefully you can and this might be your cheapest option but also
consider changing the smallest sprocket size if it has more than 11
teeth if you want to go abit faster. You might also want to consider a
whole new cassette if this option isn't much dearer. You'll definitely
need a new chain. I don't know what the current best value chain is
for quality and competitive pricing but it probably won't be a shimano
at least at the bottom end of the price scale.

James Annan said:

Martin Wilson said:

Personally I think your not firing on all
cyclinders if you think load isn't a factor with regard chain and
cassette wear even if its not the main factor but hopefully if you
read some real world experiences you might think differently.

Personally I think you're not firing on all cyclinders if you prefer to
make up some feeble straw man rather than just read what I said, which
was neither ambiguous nor inaccurate.

Make up some straw man? Never heard of this before and frankly don't
know what your talking about. I've seen enough of loads effecting
chain wear to know its a factor even if its not the main factor its
still significant in many situations. To almost eliminate load from
the formula for chain wear just seems highly illogical. You know
yourself that if that the load kept increasing there would at least
come a point where it was significant. The OP has high levels of wear
on the sprocket most used that has the most load applied. The wear on
the other sprockets is much, much lighter and from the sound of it
almost non existant. I assume the same grit and dirt moves with the
chain and goes round all the sprockets and not just the smallest. I
don't know the percentage of how much the smallest rear sprocket is
used compared to the other gears. I suspect quite high but theres
possibly more chain/teeth contact in the lower gears at any one time.
Obviously cadence is factor too. Surely though if load wasn't a factor
the wear and tear of the chain and sprocket teeth would be more
general across the whole range of cassette gears.

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

Quoted message said:

The small cog definitely has some teeth that look more shark-finny
than the others; I reckon I need to replace it.

If only some teeth (on each cog) are affected
perhaps they are meant to be that shape as an
aid to shifting. Wear would show on ALL teeth
(on one cog)

--
yours S

Nihil curo de ista tua stulta superstitione

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

Quoted message said:

soup said:

[snippage]

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 .

The small cog definitely has some teeth that look more shark-finny than
the others; I reckon I need to replace it.

This is almost certainly how they're supposed to be - some of the teeth will
be shaped to encourage easy gear shifting. Have a look at a new cassette
before writing yours off.

Quoted message said:

The two smallest cogs on the cassette are separate from the rest so
hopefully I could just buy replacements for these?

Not economically.

Quoted message said:

I guess I'll need a new chain as well?

This is what should be driving your purchasing decision. If the chain is
worn/knackered, you should replace it. If it's too far gone, you'll need a
new cassette as well. But try a chain first.

I'd recommend an SRAM chain - PC58 or PC59 depending on whether you're 9
speed or not, and make sure you get the funny link with it. (and practice
using it off the bike - there is a bit of a knack).

cheers,
clive

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

Quoted message said:

The OP has high levels of wear on the sprocket most used that has
the most load applied.

This is almost certainly not true - what you've diagnosed as wear is
probably the original shape.
This puts the rest of your argument out.

cheers,
clive