From: RONEAL@lexmark.com (Randy O'Neal)
Newsgroups: rec.bicycles.soc
Subject: Re: Tri-bar safety
Date: 26 Jan 93 16:32:31 GMT
Organization: Lexmark International, Lexington, KY
X-Disclaimer: These views are the poster's and not necessarily those of Lexmark

In article <74172@cup.portal.com>
JForester@cup.portal.com (John - Forester) writes:
 
>   I am trying to learn of the safety aspects of using tri-bars.
>The first time that I conducted a class in which tri-bars were
>used (some time ago) I had to prohibit the cyclists who had them
>from using them in the group because those tri-bars in use had no
>brake levers on them. Therefore the riders could not avoid
>running into the rider ahead when the group slowed down or the
>rider got going too fast. I have since seen some tri-bars with
>brake levers, but I don't know whether the bikes that carry these
>also have brake levers in the normal place. If so, what is the
>mechanism for linking the action? I have also heard of a rider
>who, using a tri-bar on a gentle descent, reached down to change
>to a higher gear and experienced uncontrollable oscillations. Is
>this a frequent effect, and what is its cause, if anyone knows?
 
I have a pair of Scott DH Aerobars.  The first time I rode with them
it really scared me as I did not have an 'aero brake' and my shifters
were on the stem.  I bought an extra brake lever and routed the cable
for by rear brake from the original lever through the second lever and
then to the rear brake.  Using cable housing stops appropriately, you
basically get braking action on the main brake as normal (by pulling the
cable as the lever is pulled); the braking action on the aero brake is
from the extension of the cable housing.  One advantage of this design is
the elimination of the second brake cable and the 'block-and-tackle' at
the brake caliper typically required by other setups.
 
The effect however is that the aero brake is much stronger than
the main brake.  I have not added a similar lever for the front brake as
this seems to be more than adequate.  Complaints that I have heard are
lower response from the main lever and cable return being hampered by the
excessive housing and the tight bends required for routing to and through
the second lever.  I have overcome the cable return problem with a small
device on the rear brake that employs a compression spring and a couple of
small nylon bolts cut and drilled to fit.  The cable goes through the upper
arm of the brake caliper, through a nylon bolt, the compression spring,
another nylon bolt and finally through the lower arm of the brake caliper
via the standard cable clamping bolt.  This provides enough tension to
force-feed the cable back through the housing to the brake levers.  I have
not fixed the reduced braking power on the main lever, though it is still
at an acceptable level.  A longer throw lever (I have el-cheapo Shimano
Exxage brakes and areo levers) should fix this (DiaCompe, perhaps?).
 
As for the shifters, I just recently went to Flite Controls, which
replaces the standard Scott bridge with a set of shifter bosses upon
which your shifters may be mounted.  I have less than 4 miles on them
and am already enamoured by them except for the altered grip at the
end of the bars due to the cable routing.  Indexing seems just fine
and I really like not having to reach around for the shifters once on
the bars in areo position.  I couldn't imagine riding with these or
any other aerobars with downtube shifters; the least I would accept
would be something like the SunTour Command Shifters (tried them; liked
them...).
 
If anyone's interested in a diagram or detailed description of the rear
brake lever setup or the brake cable return assist, drop me a note and
I'll probably snail-mail a diagram... the thing's a bit too
complicated for an ASCII drawing.
 
With these additions, I feel very safe on my aerobars...
 
 
Randy O'Neal                         "The above views are mine alone,
RONEAL@lexmark.com                    though they can be yours too for
Printer Attach Software Development   a nominal fee..."            __o
Lexmark International, Inc.                                       `\<,
Lexington, Ky.                                                    O/ O
 
Thoughts on Programming, Number 2:                                             
   Some years ago, when COBOL was the great white programming
   hope, one heard much talk of the possibility of executives
   being able to read programs ... nobody can seriously have
   this! ... even programmers do not read programs.
                   -The Psychology of Computer Programming,
                    Gerald M. Weinberg
Newsgroups: rec.bicycles.soc