On Sat, 04 Jun 2016 13:54:57 +0700, John B. <
slocom...@gmail.xyz>
wrote:
>But why bother. There are innumerable chain tests already published,
>there are ISO standards, and at least one US patent issued for a chain
>testing machine US4413513 A.
I don't believe that there are any test reports on the effectiveness
of using o-ring or x-ring sealed motorcycle chains on a bicycle.
Similarly, most of the tests, including the one's you list, are for
clean chains. If a sealed chain is better, it should show superior
results when filthy.
>As well, every chain manufacturer I have looked at stated that
>alignment was a factor and recommended not more than 0.1mm in 100mm
>center to center, for high speed and 0.2 for low speed chains.
Yep. Then the chain alignment is perfect, the load is distributed
along the width of the pin and bushing. When misaligned, the load is
concentrated on one end of the pin and sleeve. However, that's not
what worn bicycle chain tends to look like:
<
http://www.sheldonbrown.com/images/chain_wornpin.gif>
<
http://pardo.net/bike/pic/fail-004/000.html>
<
http://pardo.net/bike/pic/fail-006/000.html>
Note that the pin and bushing wear is roughly even across the width of
the contact area. Therefore, misalignment is a factor in power loss,
due to increased side plate rubbing, but not so much in chain wear.
Misalignment also offers a large gap for filth to enter the contact
area, which increases wear.
My guess(tm) is that the bulk of the wear and friction occurs when the
chain is wrapped around a gear and forced to change direction while
under tension. If the pin and bushing are full of dirt, it will act
as an abrasive. Chain alignment may also be a factor because a link
is only under tension and in rotation where it exits the freewheel and
again where it enters the chainwheel. It would be fairly easy to
build a chain link tester, that takes one link of a chain, puts it
under tension, cyclically rotates the chain through an angle that
approximates the freewheel exit angle, maybe adds some misalignment,
adds some lube, dirt, water, etc, and tests the relative effectiveness
of various chains, lubes, and seals. While not as definitive as
testing the full transmission and chain in a more bicycle realistic
fixture, it could produce useful results. Also, if the pin and
bushing wear pattern resemble the wear pattern of a typical worn
bicycle chain, it might prove my speculation as to where the wear is
really produced.
>As an aside, the Universities of Leeds, Sheffield and York, published
>a study: "Lee, P.M. and Priest, M. (2004) An innovation integrated
>approach to testing motorcycle drive chain lubricants." which shows
>the comparative effectiveness of several alternate chine lubricants.
>
>Interestingly the weight loss due to wear vary considerably. For the
>large sprocket a wax spray was most effective with a weight loss of
>0.12, PTFE was 0.17, Oil Drip was 0.24 and no lube was 0.40
Interesting. Are those numbers in percent of weight loss?
>For the small sprocket Wax was 0.04, PTFE 0.06, Oil drip 0.06 and no
>lube 0.27.
>
>For the chain the numbers are Wax 0.13, PTFE 0.22 Oil drip 0.03 and no
>lube 0.44.
>
>Overall, it appears that wax is preferable for chain transmission
>lubrication.
The down side of wax is that it doesn't flow and therefore voids and
gaps will fill with water and crud. Once the chain begins to wear,
there is no way to add more wax to fill the enlarged void formed by
the metal loss, except to perform the sacred chain cleaning ritual.
Wax does one thing very well, which it keep dirt out of the contact
area. I suspect that a motorcycle chain style o-ring or x-ring would
do the same or better, thus allowing the use of oil instead of wax.
Also, I suspect the reason that wax produced better numbers is that
the wax tended to stay in place, while the oil dripped out of the
chain, which is what a sealed chain prevents.
Personally, I'm not looking for a chain that will shave a few
milliseconds off someone's time trial. Also, shaving a few points off
the chain drag doesn't get my attention. What does is finding a chain
that will last for the life of the bicycle, without service,
replacement, or ritual baptism in wax or oil. Andre Jute may have
come close with his Hebie Chainglider test, but I think it can be done
with better chain design, materials, and construction.