On Fri, 16 May 2003 21:27:02 -0400, "David L. Johnson" <
[email protected]> wrote:
>On Mon, 12 May 2003 00:24:18 +0000, John Dacey wrote:
>
>> Not all Shimano's track chainrings require 1/8" chains. To their great credit, Shimano is
>> the last of the big manufacturers who still manufacture a range of 3/32" chainrings and rear
>> sprockets for track (in addition to the more common 1/8" stuff). Too bad there isn't a
>> better selection of current model 3/32" chains that are good candidates for track use to
>> complement them.
>
>You are implying an advantage to the 3/32" chain.
Drat. I meant to infer it.
>What would that be? I am not suggesting it isn't adequate, but except for a few grams of weight
>difference there is no advantage to the thinner chain/cogs. 1/8" cogs and rings will last longer,
>since there is more material that has to be worn away (but on track bikes this is not a serious
>matter, since wear is slight with a good chainline and most don't get that much mileage).
If all things were otherwise equal (which of course they're not), for many the weight issue alone
would be enough. I have heard several elite endurance track riders comment that they feel that a
3/32" chain spins up more easily. Before you dismiss this, consider that the weight difference can
be far more than "a few grams" as you claim. From the weights section of Damon Rinard's pages
archived by Sheldon
B., an Izumi track chain (and it's been drilled!!!) weighs 534 grams; by comparison a Regina 50-SL
weighs 250 grams. That's a swing that approaches a few_hundred_grams and doesn't account for a
fractional further saving with a 2 mm sprocket and chainring.
>The biggest difference is that 1/8" chain still comes with full bushings, which is a better design
>than typical derailleur chains.
That was my point in bemoaning the current lack of 3/32" chains with this feature. Perhaps you
missed a recent thread on track chains that ran concurrently with this one. An excerpt from one of
my replies there read in part: ..."The rollers of chains that are supported by full bushings will
generally have higher load carrying capabilities than bushingless chains whose rollers are borne by
bulges stamped into their inner link plates. Since many track events put large peak loads on the
chain (standing-start time trials, sprinting, etc.), fully bushed chains should ordinarily be more
capable of dealing with those loads than bushingless ones in these circumstances. The bushings will
minimize the lateral flexibility of the chain.
Additionally, most modern bushingless chains designed for multi-speed use have had their link plates
bulged, bevelled, chamfered, contoured, cut away and otherwise shaped to actually make it easier for
the chain to slide off the gear to which it's currently engaged. That's obviously not a welcome
feature in a track bike. The ideal link profile for a track chain will be a shape that helps keep
the links captive on the sprockets they engage (rather than to facilitate shifting), and the
resulting generous link proportions may also restrict side flex in the chain. That there are limited
choices of
3/32" chains that fit this description any more and that have fully bushed roller support is what
likely keeps 1/8" drivetrain parts the predominant format chosen by track riders".
Vide:http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&frame=right&th=ae34fc3516c2b974&seekm=y0V%
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