HELP: XTR/XT Hollowtech construction

[montyzuma]

Can anyone shed any light on exactly how the M960/760 cranks are
attached to the BB axle? Any way of getting them apart in order to
fiddle with the axle length for purposes of reducing the Q factor?

 

[Werehatrack]

On 14 Jan 2006 11:42:23 -0800, "montyzuma" <[email protected]>
wrote:

>Can anyone shed any light on exactly how the M960/760 cranks are
>attached to the BB axle? Any way of getting them apart in order to
>fiddle with the axle length for purposes of reducing the Q factor?

It's Octalink. With an XTR, if it's a V1 Octalink double, you might
be able to swap to the longer (triple) Octalink BB, or with either V1
or V2 you might get away with shimming the BB out from the BB shell a
bit on the right if the left crank has enough chainstay clearance.
There's nothing that you can do to change the position of the crank on
the BB shaft without reducing the amount of spline engagement, and
there's not enough of that to begin with. Octalink BB units are not
supplied in a variety of lengths like tapered square, so you don't
have much to work with if you want to fine-tune something. (In
theory, this is a Feature; the cranks made for use with an Octalink BB
are all supposed to be set up for the same BB shaft length,
eliminating the need to have multiple BB versions. In practice,
things are not always this simple.)
--
Typoes are a feature, not a bug.
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[Robin Hubert]

Werehatrack wrote:
> On 14 Jan 2006 11:42:23 -0800, "montyzuma" <[email protected]>
> wrote:
>
>
>>Can anyone shed any light on exactly how the M960/760 cranks are
>>attached to the BB axle? Any way of getting them apart in order to
>>fiddle with the axle length for purposes of reducing the Q factor?
>
>
> It's Octalink. With an XTR, if it's a V1 Octalink double, you might
> be able to swap to the longer (triple) Octalink BB, or with either V1
> or V2 you might get away with shimming the BB out from the BB shell a
> bit on the right if the left crank has enough chainstay clearance.
> There's nothing that you can do to change the position of the crank on
> the BB shaft without reducing the amount of spline engagement, and
> there's not enough of that to begin with. Octalink BB units are not
> supplied in a variety of lengths like tapered square, so you don't
> have much to work with if you want to fine-tune something. (In
> theory, this is a Feature; the cranks made for use with an Octalink BB
> are all supposed to be set up for the same BB shaft length,
> eliminating the need to have multiple BB versions. In practice,
> things are not always this simple.)

Wrong, Kimosabe. It's a Hollowtech II with integrated spindle. There's
absolutely nothing OP can do to change to effect chainline or Q-factor.


Robin Hubert

 

[Werehatrack]

On Sat, 14 Jan 2006 23:22:09 GMT, Robin Hubert <[email protected]>
wrote:

>Wrong, Kimosabe. It's a Hollowtech II with integrated spindle. There's
>absolutely nothing OP can do to change to effect chainline or Q-factor.

Oh, bloody. So the Shimano-or-nothing movement (which has only one
willing participant IMO) has expanded downward into the XT as well?
Not good news.

Octalink was bad enough. This thing's not enough better than the
stuff that's open-standard to justify getting slaved to a single
source (at least, not for a lot of people), and I'm betting that
before the patents run out, Shimano will have dumped it in favor of
their *next* "Ultimate New Thing", ensuring that the existing
installed base will not be interesting to the aftermarket replacement
parts suppliers.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

 

[Qui si parla Campagnolo]

montyzuma wrote:
> Can anyone shed any light on exactly how the M960/760 cranks are
> attached to the BB axle? Any way of getting them apart in order to
> fiddle with the axle length for purposes of reducing the Q factor?

Cannot take them apart...you are pretty much SOL. The distance between
the crank arm pedal holes IS larger in spite of shimano propaganda.
There are plenty of really good MTB cranks on the market that use the
old fashioed square taper BB..like first gen XTR or XT-ebay or google
search.

 

[Hank Wirtz]

Werehatrack <[email protected]> wrote in
news:[email protected]:

> On Sat, 14 Jan 2006 23:22:09 GMT, Robin Hubert <[email protected]>
> wrote:
>
>>Wrong, Kimosabe. It's a Hollowtech II with integrated spindle. There's
>>absolutely nothing OP can do to change to effect chainline or Q-factor.
>
> Oh, bloody. So the Shimano-or-nothing movement (which has only one
> willing participant IMO) has expanded downward into the XT as well?
> Not good news.
>
Not Just XT, but LX (and 105 for 2006) as well. You could filldle with
chainline by shuffling the bearing spacers, since a 68mm BB shell uses 2
spacers on the right if you have a clamp-on FD. Take away 1 each for E-type
FD and 73mm shell to reduce the chainline, or add the one from the left to
increase it.

But, yeah, nothing to do for q-factor.

 

[montyzuma]

I saw an article recently in one of the magazines - you know, the
"Inside the pro's bike" profile thing, where the pro in question had
the axle specially modifies to reduce Q factor. I suppose Shimano did
it for him, but since they're unlikely to do it for me I've had a look
at the problem with a couple of light engineering shops. Cutting the
splines on the left side 7.5mm futher in, shortening the axle & cutting
the threads inside deeper is easy enough, but not with the right arm
still attached. Hence attempts to figure out how to remove the
spider/arm. It looks like its pressed then swaged?
Anyone know anyone at Shimano who could add light?
For interests sake, these are my meaurements of the Q distances of the
cranks:
Dura Ace 7700 (9speed) 145 mm
DA triple 7700 154
XTR M960 167
XT M760 178