mmur-@teleport.com
While we debate whether OBRA should have junior gear limits it would make
some sense to consider what you need to do to meet the gear limits that USCF
has, as described below. Imagine a kid new to bike racing, without the
support of a cycling adult, trying to figure out how to do this. From my
point of view we need to balance the possible benefits of gear limits
against the negative impact on participation. Can we really afford to lose
even one potential junior racer?
It is also interesting that I don't hear any attempts to limit gearing in
mountain biking. Clearly if pushing big gears is a real problem it is much
more likely that the junior will be grinding along on a mountain bike.
I propose that OBRA adopt rules that require gear limits at the track, where
it is easy to do and may have some real benefits, but ignore road gear
limits.
Mike Murray
"M. Creed Sr." <mcre-@msn.com> wrote in message
news:<91ltag-@nnrp1.deja.com>...
There is a standard way of meeting the rollout.
DO NOT USE A 45 CHAINRING! There are too many problems with front
derailleur height adjustment and shifting problems. Depending on the
frame construction the front derailleur may not be able to move enought
to match a 45T ring. Braze-on tab slot is not long enough and tubing
flare (some carbon and aluminium frames) will not accept lower postion
of the front derailleur. Use a 52T front chain ring, easily available
and virtually no adjustment to front Derailleur. To make the required
14T in the rear cassette is made possible by using any 9 speed cassette
that starts with a 12T cog. You will replace the second position 13T
with a spare 14T (available by itself from most shops or from Loose
Screws in Oregon for about $5.00). Most of us have spare cogsets, or
ones that are used that we can pull the 14T. In some cases that could
give you back to back 14's, thats ok.You end up with a 1st position
12(which you can block out) and a second postion 14T. Internationally,
blocking out isn't allowed, but they grind the teeth off the 12T to
render it unuseable. They adjust the set screw to the 2nd cog,
essentially making it an 8 speed.Granted not the best situation, outside
of Shimano & Campy making 14x23 cassettes. This configuration is
standard fix in Europe for UCI races and for the national team.
MC
In article <91ep6p-@glisan.hevanet.com>,
"Martin Clan" <mar-@hevanet.com> wrote:
Boy did I blow it by not printing the complete passage figuring that the
columns would get all screwed up.
Here are the ratios also provided in the complete text:
Chaingear Ratios
2.2.024 For Junior Men & Women, the authorized maximum chaingear ratio
is
7.93 meters.
Gear Development Charts
The charts below give development (distance covered in one revolution of
the
cranks) for various combinations of chain ring and rear sprocket,
assuming
26.5 inch wheels. Note that other wheel sizes are widely used. For
example,
27 inch wheels have a development about 2% larger than the figures
listed
below. The formula for development is:
(wheel diameter) x pi x (chain ring teeth)/(sprocket teeth)
where pi is about 3.14.
These charts are provided only for general guidance in selecting gears.
Do
not depend on calculations or charts to determine whether a particular
bicycle satisfies gear restrictions - use the roll-out test (distance
traveled by the bicycle in one revolution of the crank with the tires
inflated to racing pressure).
Gear Development (meters)
chain ring teeth
44 45 46 47 48 49 50 51 52 53 54
55
12 7.75 7.93 8.11 8.28 8.46 8.63 8.81 8.99 9.16 9.34 9.52 9.69
13 7.16 7.32 7.48 7.65 7.81 7.97 8.13 8.30 8.46 8.62 8.78 8.95
14 6.65 6.80 6.95 7.10 7.25 7.40 7.55 7.70 7.85 8.01 8.16 8.31
Gear Development (feet, inches)
chain ring teeth
44 45 46 47 48 49 50 51 52
53
54 55
12 25'5" 26'0" 26'7" 27'2" 27'9" 28'4" 28'11" 29'6" 30'1" 30'8" 31'3"
31'10"
13 23'6" 24'0" 24'7" 25'1" 25'7" 26'2" 26'8" 27'3" 27'9" 28'3" 28'10"
29'4"
14 21'10" 22'4" 22'10" 23'3" 23'9" 24'3" 24'9" 25'3" 25'9" 26'3" 26'9"
27'3"
15 20'4" 20'10" 21'3" 21'9" 22'2" 22'8" 23'2" 23'7" 24'1" 24'6" 25'0"
25'5"
"Theodore Heise" <the-@netins.net> wrote in message
news:20001115205-@netins.net...
Casey Kerrigan writes:
So if you could only block off one gear with the set screw then it
sounds
like blocking off gears will not work. This means all junior riders
will
have to buy new gears in order to race.
Couldn't you just buy a longer set screw? If so, it's a lot cheaper
than
a chainring.
Ted
--
Theodore W. Heise <the-@netins.net> West Lafayette, IN, USA
PGP public key: http://showcase.netins.net/web/twheise/theise.asc
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