Are 12-21 cassettes simply stupid ??

Ron Ruff wrote:
One aspect of this that is often overlooked is the effect of chain
tension on efficiency...

Yeah, exactly. Look at this:

http://nukku.net/no/nbikes.html

Nikolas Ojala

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Static truth is dead truth and only
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Nikolas Ojala wrote:
Ron Ruff wrote:
One aspect of this that is often overlooked is the effect of chain
tension on efficiency...

Yeah, exactly. Look at this:

http://nukku.net/no/nbikes.html

Thanks for the link. Am a bit skeptical of his results, though. If he
only tested two data points and got a 0.6% difference that isn't even
significant. Plus, his assertion that friction is the cause for chain
inefficiencies is wrong, according to Skinner's test.

Wrote:
Jasper Janssen wrote:
I don't see what using the smallest cogs with the small ring has to
do
with using the smallest cogs, period. You would normally use those
with
the big ring.

Most people can't use an 11 or 12 and probably even a 13 effectively
unless they're going downhill without curves. I don't use an 11 or 12
(I have recently gotten to the point where I can occasionally make use
of a 13) but if I had one, I would most likely use it in combination
with the 39 front on rolling roads where I need the small front ring.
It would allow me to make all the shifts at the rear which is less of
a
hassle than the front, and, especially, avoid double shifts. Sure,
there might be some rubbing or noise, but as long as it's not sawing
through the seat stay I'll tolerate it until I need to shift down. I
make these types of shifts now with the 13, and can envision them with
an 11 or 12, while I can only see using them with the 53 under very
rare circumstances.

Of course, this is all very individual. It depends on your strenghts
and preferences for riding style and the terrain, and implies matching
them to your bicycle's gearing, something that is discouraged by the
_general_ unavailability of customized cassettes or more cassette kits
that would allow a cyclist to swap out cogs easily depending on their
ride.

If you're talking about cassettes for road bikes, remember that there
are a lot of regular club racers out there - crits and road races,
which often require the top end of the cassette. You might spend less
than 1% of the time in the 11 (12 is top for me), but it happens in the
bunch sprint where you all wind up for the 10-15 second gallop. 12-21
cassettes get used by rapid road riders that live in flat terrain and
racers. They are probably irrelevant for the weekend coffee shop
run[1]. If you don't race and don't have a use for a 12, junk it and
get a 13-23/26/29 or whatever you like - don't get a 12-21 just 'cos it
looks racy.

Ritch

[1]The coffee shop run on the weekend could just about be done on a
single speed anyway...


--
ritcho