On Sep 19, 5:26 am, !Jones <
[email protected]> wrote:
> On Tue, 18 Sep 2007 21:54:31 -0700, in rec.bicycles.tech JG
>
> <[email protected]> wrote:
> >It's hard to see how you would run the cable and housing with the, er,
> >brazed on center-pull, underneath the seat stays...
>
> >JG
>
> Assume it's an... err... somewhat oddball frame and that the cable
> routing will be fine if not better. Will there be any reason not to
> do it that way that would go to the functionality of the brakes?
>
> Jones
There's the question of whether the cable carrier will be able to be
in a spot that gives good mechanical advantage (presuming the routing
setup would use a carrier as opposed to dual cables, and I'm also
assuming this would be a typical setup where the carrier is in front
of the seattube and the straddle is going around the tube). Lower
tends to be better. I wish I knew how to quantify it accurately, but
if the cable carrier's nut is gonna be more than about 4 inches way
from the cable anchor points, braking will probably suffer. That 4
inches is a fudged number but i think it's about right. This could
definitely be a problem if the frame has a long-ish rear end. If it
seems like it's going to be too far away, and you still want to do
under-ss mounting (ie, for the sake of getting the best routing), then
you could just run the main cable through the seattube somehow,
allowing you to get the straddle nice and low. I'm not totally
confident on this, but I kinda suspect that there are millions of BMX
frames that really should have been built this way.
You also need to make sure that the chosen position provides clearance
from the rider and other parts of the bike.
It might also be worth mentioning that the alignment/symmetry of 990
bosses is important because it doesn't take much to cause some brake
arms to rub on each other.