DuraAce 7900 Crankset

I've read on a few sites that the BB axle is aluminium (aluminum).

Is this true? Is Shimano really running an Al BB axle?

If so, I'm surprised it's strong enough.

As I understand it, one of the A grade competitors in our club race on
Saturday stripped the spline off the axle and had to retire. Could this
be true?

--
JS.

James wrote:

I've read on a few sites that the BB axle is aluminium (aluminum).

Is this true? *Is Shimano really running an Al BB axle?

If so, I'm surprised it's strong enough.

Shimano two-piece cranks use 24mm diameter spindles. Given that the
root of the square taper on an old steel spindle was about 15mm, it
seems like 24mm aluminum should be more than enough. The old Magic
Motorcycle cranks used a big-bored 25mm aluminum spindle, and GT/FSA
even made freestyle cranks with a 25mm aluminum spindle. I put a pair
of the latter on my wife's stoutest bike way back in the twentieth
century, and they are still going strong.

For the first few iterations, Shimano two-piece cranks had steel
spindles on the more expensive models (presumably for its stiffness)
and aluminum spindles on the cheaper variations. It would not
surprise me to find that aluminum is used across the line now, just to
minimize weight.

Chalo

On May 13, 10:50*pm, James wrote:
I've read on a few sites that the BB axle is aluminium (aluminum).

Is this true? *Is Shimano really running an Al BB axle?

If so, I'm surprised it's strong enough.

As I understand it, one of the A grade competitors in our club race on
Saturday stripped the spline off the axle and had to retire. *Could this
be true?

--
JS.

Shimano's 6600 Ultegra cranks had an aluminum spindle. The 6601s had a
steel spindle, touting lighter/stiffer/stronger. I have both, and they
are indeed cranks/spindles.

On 5/14/2012 7:42 PM, Jay Beattie wrote:
On May 14, 4:42 pm, wrote:
On 14/05/12 19:13, raamman wrote:

On May 13, 10:50 pm, wrote:
I've read on a few sites that the BB axle is aluminium (aluminum).

Is this true? Is Shimano really running an Al BB axle?

If so, I'm surprised it's strong enough.

As I understand it, one of the A grade competitors in our club race on
Saturday stripped the spline off the axle and had to retire. Could this
be true?

if the spline was indeed stripped I would think it is due to improper
installation and not a material defect

Possibly, which is more funny because the bike owner is a bike shop
owner too ;-p


In the olden days, you had to fuss with a lot of different wrenches
and bearings and cones and cups, etc., but it was practically
impossible to overtighten anything -- and the parts either went
together or they didn't (although you could cross-thread a freewheel
pretty easily if you had too many beers). Anyway, with old-style
cranks, it was a square peg into a square hole. You could put one on
in the dark.

With greased or un-greased tapers? And insufficient torque on
installation would lead to future problems. Not to mention the ISO-JIS
compatibility issues.

Octalink introduced the potential for an apparently good
fit that wasn't, and maybe the splined interface on the new two-piece
cranks provides the same opportunity for failure. It is truly sad when
a wrench can get it wrong.

That same potential is/was there with both square taper and cottered cranks.

--
Tºm Shermªn - 42.435731°N, 83.985007°W
Post Free or Die!

On May 20, 4:19*pm, "Tom $herman (-_-)" ""twshermanREMOVE\"@THI
$southslope.net" wrote:
On 5/14/2012 7:42 PM, Jay Beattie wrote:









On May 14, 4:42 pm, *wrote:
On 14/05/12 19:13, raamman wrote:

On May 13, 10:50 pm, * *wrote:
I've read on a few sites that the BB axle is aluminium (aluminum).

Is this true? *Is Shimano really running an Al BB axle?

If so, I'm surprised it's strong enough.

As I understand it, one of the A grade competitors in our club race on
Saturday stripped the spline off the axle and had to retire. *Could this
be true?

if the spline was indeed stripped I would think it is due to improper
installation and not a material defect

Possibly, which is more funny because the bike owner is a bike shop
owner too ;-p

In the olden days, you had to fuss with a lot of different wrenches
and bearings and cones and cups, etc., but it was practically
impossible to overtighten anything -- and the parts either went
together or they didn't (although you could cross-thread a freewheel
pretty easily if you had too many beers). *Anyway, with old-style
cranks, it was a square peg into a square hole. You could put one on
in the dark.

With greased or un-greased tapers? *And insufficient torque on
installation would lead to future problems. *Not to mention the ISO-JIS
compatibility issues.

Octalink introduced the potential for an apparently good
fit that wasn't, and maybe the splined interface on the new two-piece
cranks provides the same opportunity for failure. It is truly sad when
a wrench can get it wrong.

That same potential is/was there with both square taper and cottered cranks.

Sure, anything can be screwed up, but with square taper, you had to
work at it -- grease or not, split cranks were exceptionally rare. A
crank coming lose could happen, but ordinarily, you just reefed on the
peanut butter wrench, and the crank was good to go. And maybe some
people unintentionally mixed ISO/JIS. I did it intentionally and
never had a problem.

This is not to say that current cranks are a problem. I don't know
that to be the case. I did mis-fit an Octalink once, so I know that
can be done. I don't know how hard Jame's friend had to work to screw
up a two piece crank. I've never had a problem with mine, but if a
shop owner can get it wrong . . . that signifies to me that an
apparently good fit can be a bad fit, but who knows, maybe the guy was
inebriated and putting the thing on with a sledge hammer.

-- Jay Beattie.