Energy losses in chain drive?

The most recent 'is a more expensive bike 'worth it' ' thread made me
wonder what the effect of a brand new transmission was when compared to
worn cogs and a well travelled chain.

My /hunch/ is that this would add more speed than a few ounces of weight
saved on the frame. Of course a /hunch/ isn't the best thing to go on
if there are data and an analysis available. Surely there is an
engineering department in a university that could measure the difference
in Watts even if not in mph.


--
PETER FOX Not the same since the e-commerce business came to a .

www.eminent.demon.co.uk - Lots for cyclists

Peter Fox wrote:
The most recent 'is a more expensive bike 'worth it' ' thread made me
wonder what the effect of a brand new transmission was when compared
to worn cogs and a well travelled chain.

What extra losses could there be when the worn chain still meshes well with
cogs that have worn at the same rate?

~PB

On Sun, 26 Nov, Pete Biggs wrote:
Peter Fox wrote:
The most recent 'is a more expensive bike 'worth it' ' thread made me
wonder what the effect of a brand new transmission was when compared
to worn cogs and a well travelled chain.

What extra losses could there be when the worn chain still meshes well with
cogs that have worn at the same rate?

I don't think worn components mesh so well - I think there's more
sliding on the tooth when ring and tooth are worn, even though they
still interlock.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

"Peter Fox" wrote in
message news
The most recent 'is a more expensive bike 'worth it' ' thread made me
wonder what the effect of a brand new transmission was when compared to
worn cogs and a well travelled chain.

My /hunch/ is that this would add more speed than a few ounces of weight
saved on the frame. Of course a /hunch/ isn't the best thing to go on if
there are data and an analysis available. Surely there is an engineering
department in a university that could measure the difference in Watts even
if not in mph.

There could well be more resistance in the new transmission because the
bearing surfaces have not bedded in.

I can't think of any reason, other than curiosity, why someone would want to
do the specific investigation. Pros and posers discard drive train bits
well before they are worn out, normal cyclists happily plod on with old but
functioning kit not worrying about performance loss. Who's the beneficiary
that would pay for the research?

I'm sure that related research has been done and a literature search for
duplex chain transmission losses would trawl up something that one could
extrapolate from.

My biggest performance boost would be obtained by personal weight loss and
not by upgrading/replacing wheels/frame/drivetrain*

*circle your favourite performance enhancer

-=V=-

Peter Fox wrote:
The most recent 'is a more expensive bike 'worth it' ' thread made me
wonder what the effect of a brand new transmission was when compared
to worn cogs and a well travelled chain.

My /hunch/ is that this would add more speed than a few ounces of
weight saved on the frame. Of course a /hunch/ isn't the best thing
to go on if there are data and an analysis available. Surely there
is an engineering department in a university that could measure the
difference in Watts even if not in mph.

Have a look at industrial chain suppliers - they'll probably have some info
that may be interesting even if the application isn't identical!

Peter Fox wrote on 26/11/2006 01:51 +0100:
The most recent 'is a more expensive bike 'worth it' ' thread made me
wonder what the effect of a brand new transmission was when compared to
worn cogs and a well travelled chain.

My /hunch/ is that this would add more speed than a few ounces of weight
saved on the frame. Of course a /hunch/ isn't the best thing to go on
if there are data and an analysis available. Surely there is an
engineering department in a university that could measure the difference
in Watts even if not in mph.



http://www.hw.ac.uk/mecwww/research/mdk/res.htm
http://www.sdearthtimes.com/et1199/et1199s13.html ( Journal of
Mechanical Design -- December 2001 -- Volume 123, Issue 4, pp. 598-605)
http://www.ingentaconnect.com/conten...00004/art00001

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

On Sun, 26 Nov 2006 02:17:05 -0000
"Pete Biggs" wrote:

Peter Fox wrote:
The most recent 'is a more expensive bike 'worth it' ' thread made
me wonder what the effect of a brand new transmission was when
compared to worn cogs and a well travelled chain.

What extra losses could there be when the worn chain still meshes
well with cogs that have worn at the same rate?

If energy is being lost, there'll be heat. So you could make a crude
empirical test.

--
not me guv

Nick Kew wrote on 26/11/2006 10:53 +0100:

If energy is being lost, there'll be heat. So you could make a crude
empirical test.


See the second link in my post ^

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

Pete Biggs wrote:
Peter Fox wrote:
The most recent 'is a more expensive bike 'worth it' ' thread made me
wonder what the effect of a brand new transmission was when compared
to worn cogs and a well travelled chain.

What extra losses could there be when the worn chain still meshes
well with cogs that have worn at the same rate?

AFAIK it doesn't work like that. The chain stretches as it wears so the
distance between the rollers increases. After a while only the first few
teeth on the cog actually have a good grip on the chain, further up the
chain stretch means that the gap between the roller and its tooth gets
progressively larger. This is why a worn chain wears the cogs quicker
because all the load is taken by only the first few teeth instead of being
spread evenly around the cog.
On motorbikes, a shaft drive produces significantly less hp at the rear
wheel compared to a chain drive. A chain is indeed a remarkably efficient
method of transmitting power.

--

Geoff

GeoffC wrote on 26/11/2006 12:43 +0100:

This is why a worn chain wears the cogs quicker
because all the load is taken by only the first few teeth instead of being
spread evenly around the cog.


Doesn't work like that if you think about it. It may have a higher load
on the one that is engaged but it is engaged for only a small part of
the rotation cycle instead of lower load spread over a longer part of
the rotation cycle. The load x engagement time will be a constant.

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci