On May 13, 10:06 pm,
[email protected] wrote:
> Oh, this shows the Isis crank interface, which is dead anyway because
> it is a flawed design based on the wrong assumptions about
> steel-to-aluminum interfaces. We have also read about spindle
> failures, here in this newsgroup. However, the endless pdf does not
> show what locates the spindle in the bearings, radially or axially.
> --
> Jobst Brandt
The spindle is located radially by a slip fit in the ID of the
bearings. It is fixed to the right crank with a press fit. On the left
crank, it is tightened onto splines, and axially preloaded (on my XTR)
with a thread and nut system on the left crank arm.
http://www.cyclesuperstore.ie/shop/pc/catalog/description/xtrinstall.jpg
Most every slip fit axle/spindle over cartridge bearing design I've
used develops some noise. And while I haven't seen it yet, it
certainly is possible for external aluminum bearing retainers to
develop some issues with threads or alignment. I've obtained a not yet
general release XTR carbon fiber bearing holders that would seem to
solve a number of issues. They do require a 92 mm unthreaded BB shell
though so will not retrofit. No threads, no thread or alignment
issues. And incredible support compared to external retainers. And
something else new barely visible on the second link below is that
there is a plastic dust cap extending into the ID of the bearing
(sorry, I'm not in a position to take better pictures). The spindle
slips onto this plastic rather than the metal of the cartridge
bearing. This should eliminate the noise of the old interface. I'll
have to see when I've built my new frame.
http://techdocs.shimano.com/media/t...001/SI_0053A_001_En_v1_m56577569830625426.pdf
http://www.pivotcycles.com/tech.php
This represents a very cool evolution of the external oversized
bearing systems since the original Magic and Sweet systems started the
whole thing. When this carbon fiber BB bearing holder becomes
available in a 30mm size, things will get significantly lighter,
stronger, and stiffer and we will not have to depend on proprietary
systems from Cannondale and Trek for something better. It is not
proprietary in the sense that a number of cranks will fit onto this
system without modification where Cannondale and Trek cranks only fit
one bike.