magura/KH brake mod



C

cline

Guest
Unsatisfied with the usual brake lever setup I decided to try my hand at
modifying the HS33 setup on my KH24. The basic idea was to produce a
horizontally- rather than vertically-activated break handle (i.e. pull
forward, not up). I made a custom reversed lever and coupled it to a
handle which uses the brake mount tube on the KH seatpost to hold it in
place.

Hopefully the picture helps explain the setup.

After one test ride, the system seems promising. The lever feels good
in use, possibly more stable than a normal extension. At the moment the
braking action is very smooth, but requires too much force and I can't
lock the wheel. I assume this is from air in the master cylinder (which
exploded when jostled while partly disassembled), but I may not have
enough mechanical advantage where the string is currently connected. It
will be nice to add a position adjustment for the lever, and replace the
string with an adjustable linkage like those used on model airplanes.


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cline - Physics Inspector
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i'm sure your problem is air, as there is barely any force needed to
push the piston in at the lever end.


that is a very cool idea, are you able to reach around and pull it
comfortably?


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Brian MacKenzie - LAN Solo

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Interesting design. I like the ability to use two fingers to pull up on
the lever. I have gotten used to just one finger on the actual lever,
but would prefer an extender that extends on both sides like your
design. I tried the one sided extender and had to remove it after
continually bruising the side of my leg. I had dremelled it down to
keep it from hitting, but still didn't like it.


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bugman - Survivor 2004 Wolfman Duathalon

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his own happiness as the moral purpose of his life, with productive
achievement as his noblest activity, and reason as his only absolute.
Ayn Rand
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Brian MacKenzie wrote:
> I'M SURE YOUR PROBLEM IS AIR, AS THERE IS BARELY ANY FORCE NEEDED TO
> PUSH THE PISTON IN AT THE LEVER END.
>
> Thanks. Time to search for brake bleeding threads.
>
> THAT IS A VERY COOL IDEA, ARE YOU ABLE TO REACH AROUND AND PULL IT
> COMFORTABLY?
>
> There's no problem at all reaching the bar the way it is. The angle
> of the pics might not show that very well. The most comfortable grip
> so far is with index and pinky on the seat handle and the middle two
> fingers on the brake bar, but that's just a first impression after
> maybe 200 yards of downhill.
>
> WHAT IF YOU PUT THE BRAKE HANDLE CLOSER TO THE SEAT HANDLE, SO YOU CAN
> SQUEEZE IT WITH THE FINGER TIPS OF THE HAND ALREADY HOLDING THE
> HANDLE? (OR MAYBE YOU CAN, BUT IT APPEARSTO BE QUITE FAR BACK)
>
> Moving it forward a little will improve it, though the reach works OK
> now. Experimenting with the linking string made this clear, so it is
> set up with a lot of play right now. To keep things simple, I plan to
> screw a block of nylon to the far end of the alignment shaft so that
> the nylon hits the main seatpost tube stopping the bar. This will be
> especially easy since the shaft is actually a piece of 'all thread'
> (http://tinyurl.com/57nvq) with a brass tube crimped over it to act
> as a sort of bushing. All I need to do is cut off some of the brass
> and drill and tap a chunk of nylon.



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