Re: A problem with gears.

Pete Biggs

Simon Brooke wrote:
> Chains in totally enclosed chain cases, particularly in partial oil
> baths, last extraordinary lengths of time. I've seen chains no larger
> than bicycle chains on industrial equipment lasting with little
> adjustment for years of continual use. Timing chains on cars similarly
> last a very long time.

1. The torque in those applications tends to be far less than that applied
to bicycle chains.

2. Enclosed bike chains are used on single gear and hub gear bikes--these
chains naturally last longer than derailleur chains because of their size
and chainlines.

> By contrast, of course, the chain in a mountain
> bike used frequently in muddy conditions wears quickly however
> carefully and regularly you clean and relube it.

One reason MTB drivetrains wear faster than road bikes' is that smaller
chainrings and sprockets are used.

> This is why I'm interested in using gearboxes and fixed chain lines on
> mountain bikes - if you can get it to work efficiently, then you can
> enclose the chain, using the chain case as a structural element of the
> rear swing arm; and that will give you a much more reliable
> transmission.
>
> 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
seems far from clear to me as there are so many factors.

~PB

James Annan

Pete Biggs wrote:

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

Martin Wilson

On Mon, 13 Dec 2004 06:38:35 +0900, James Annan
<still_the_same_me@hotmail.com> wrote:

>Pete Biggs wrote:
>
>>> 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
>> 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.

If you can't find the relevant postings I'm sure I can find the
subject headings for you.

Clive George

"Martin Wilson" <martin.w6@ukonline.co.uk> wrote in message
news:knopr0d570sar3o0qucroi3q68jtfn6hoe@4ax.com...
> On Mon, 13 Dec 2004 06:38:35 +0900, James Annan
> <still_the_same_me@hotmail.com> wrote:
>
> >Pete Biggs wrote:
> >
> >>> 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
> >> 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

Simon Brooke

in message <knopr0d570sar3o0qucroi3q68jtfn6hoe@4ax.com>, Martin Wilson
('martin.w6@ukonline.co.uk') wrote:
> On Mon, 13 Dec 2004 06:38:35 +0900, James Annan
> <still_the_same_me@hotmail.com> wrote:
>
> >Pete Biggs wrote:
>
>>> 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.

--
simon@jasmine.org.uk (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

James Annan

Martin Wilson wrote:


>
> 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/

Pete Biggs

James Annan wrote:
> 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

dkahn400

Pete Biggs wrote:

> 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...

Clive George

"Pete Biggs" <pwrinkledgrape{remove_fruit}@biggs.tc> wrote in message
news:325n25F3gi30lU1@individual.net...
> James Annan wrote:
> > 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.

> 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

Pete Biggs

dkahn400 wrote:
> Pete Biggs wrote:
>
>> 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

Pete Biggs

Clive George wrote:

>> 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.

~PB
(edit in square brackets)

Pete Biggs

dkahn400 wrote:
> Pete Biggs wrote:
>
>> 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

Clive George

"Pete Biggs" <pwrinkledgrape{remove_fruit}@biggs.tc> wrote in message
news:325u7bF3j780eU1@individual.net...
> Clive George wrote:
>
> >> 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.

cheers,
clive

Pete Biggs

Clive George wrote:

>>>> 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