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ISCG 05 was developed by the engineers at e.thirteen components
with support and feedback from members of the ISCG 05 consortium.
Its conception was the result of several years of the bicycle
industry using the original ISCG standards, pioneered by a
cooperative effort between Bob Barnett (Mr. Dirt) and Mountainspeed.
The original ISCG was a huge success but was originally planned
to fit only standard bottom bracket types. With the widespread
use of BMX type bottom brackets and the introduction of the
ISIS Overdrive standard, a new chainguide mounting standard
was needed.
The ISCG 05 project has been in the making for over a year
at this time. While developing this new standard, we decided
to start with a clean sheet of paper and incorporate everything
that we had learned about chainguides and mounting since 2000.
In April of 2003, the basis of the new standard was proposed.
Industry wide, there was much great feedback given. At Interbike
2003, members of the ISCG 05 consortium met in person and
discussed the details of this proposed new standard. Revisions
were made, and ISCG 05 was born! Special thanks go to George
Dubois of Truvativ for taking the time to spread the word
about ISCG 05 to product developers around the bicycle industry.
The goals for this new ISCG 05 standard were multifold. This
new standard improves on the original ISCG in several important
ways:
- The ISCG 05 is compatible with all currently available
bottom bracket types that we are aware of. Drawings are
provided for standard, BMX, and ISIS Overdrive designs.
The new ISCG 05 is broad enough in its scope that other
types may be integrated in the future. This addition offers
simplified chainguide installation for shops and consumers
and aims to cut down on chainguide model variations industry
wide.
- The new ISCG 05 standard tab clocking is now defined in
relation to an imaginary line running from the center of
the bottom bracket shell to the center of the rear wheel.
This clocking method is identical to that used with conventional
derailleurs. This aims to eliminate the guesswork that plagued
the past standard. Big thanks to James Gardner and Dan Connors
at Cannondale for this well thought out addition to the
standard.
- A new rotated standard allows frame designers flexibility
to use low non-elevated chainstays on long travel frames.
This rotated standard uses the same bolt circle and relative
positioning as the ISCG 05, repositioned 14 degrees counter-clockwise.
- Tab thicknesses, tab offset, and tab parallelism to the
bottom bracket face are now all defined simply and completely.
This aims to eliminate the guesswork that previous ISCG
users faced.
- A new larger 73mm bolt circle diameter makes for more
robust mounting. ISCG 05 frame tabs can be stronger than
previous incarnations, and chainguide rotation is less possible.
- Outside vendor supplied ISCG 05 adapter plates are now
governed by a 2.5mm thick mounting width. This allows simplified
setup for consumers using external cup bottom brackets like
the Raceface X-Type and Shimano Saint. Big thanks to Bryn
Johnson from Raceface for this forward thinking addition.
Thank you for taking the time to read through the included
documents carefully, and happy trails!
Sincerely,
Dave Weagle
Technical Director, e.thirteen components
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