ISIS bottom bracket

Discuss light weight issues concerning road bikes & parts.
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Ye Olde Balde One
Posts: 495
Joined: Sun Oct 19, 2003 4:26 pm
Location: Santa Monica, CA

by Ye Olde Balde One



It's too heavy :twisted:

Here are the specs on one;

New Scandium ISIS Drive BB
-CNC machined hollow Scandium spindle with 7075 X-Long™ Bolts
-Carbon body, alloy cold forged cups
-2pcs High Rolling sealed bearings
-108mm ISIS Drive for Double
.68xBSA 1.37"x24T, R/L cups
.Chainline: 43.5mm
.Weight: 118g (108mm,w/o bolts)
Ride lightly!

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Delpi
Posts: 163
Joined: Tue Oct 28, 2003 4:32 pm
Location: Italia

by Delpi

Weight: 118g (108mm,w/o bolts)


:shock: Are you sure? Only 118g!!!!
I want it!!!!!
Ciao Zauri

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Ye Olde Balde One
Posts: 495
Joined: Sun Oct 19, 2003 4:26 pm
Location: Santa Monica, CA

by Ye Olde Balde One

Delpi wrote:
Weight: 118g (108mm,w/o bolts)


:shock: Are you sure? Only 118g!!!!
I want it!!!!!


Yes I'm sure :!:
Ride lightly!

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spytech
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Joined: Wed Oct 22, 2003 12:34 pm
Location: New York City
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by spytech

Ye Olde Balde One wrote:


It's too heavy :twisted:

Here are the specs on one;

New Scandium ISIS Drive BB
-CNC machined hollow Scandium spindle with 7075 X-Long™ Bolts
-Carbon body, alloy cold forged cups
-2pcs High Rolling sealed bearings
-108mm ISIS Drive for Double
.68xBSA 1.37"x24T, R/L cups
.Chainline: 43.5mm
.Weight: 118g (108mm,w/o bolts)


sorry but alu and scandium BB scare me, i would like a chromo axle i would rather lose 22g of weight savings and have the stiffness and strength of a chromo axle than to save 22g. anyone with me? AC isis BB is what i am going with all the way.

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Ye Olde Balde One
Posts: 495
Joined: Sun Oct 19, 2003 4:26 pm
Location: Santa Monica, CA

by Ye Olde Balde One

spytech wrote:
Ye Olde Balde One wrote:


It's too heavy :twisted:

Here are the specs on one;

New Scandium ISIS Drive BB
-CNC machined hollow Scandium spindle with 7075 X-Long™ Bolts
-Carbon body, alloy cold forged cups
-2pcs High Rolling sealed bearings
-108mm ISIS Drive for Double
.68xBSA 1.37"x24T, R/L cups
.Chainline: 43.5mm
.Weight: 118g (108mm,w/o bolts)


sorry but alu and scandium BB scare me, i would like a chromo axle i would rather lose 22g of weight savings and have the stiffness and strength of a chromo axle than to save 22g. anyone with me? AC isis BB is what i am going with all the way.


I don't think your going to get less strength, and the Al BB would be stiffer because of the thicker walls I think.

The AC still isn't available :!:
Ride lightly!

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spytech
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Joined: Wed Oct 22, 2003 12:34 pm
Location: New York City
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by spytech

Ye Olde Balde One wrote:
spytech wrote:
Ye Olde Balde One wrote:


It's too heavy :twisted:

Here are the specs on one;

New Scandium ISIS Drive BB
-CNC machined hollow Scandium spindle with 7075 X-Long™ Bolts
-Carbon body, alloy cold forged cups
-2pcs High Rolling sealed bearings
-108mm ISIS Drive for Double
.68xBSA 1.37"x24T, R/L cups
.Chainline: 43.5mm
.Weight: 118g (108mm,w/o bolts)


sorry but alu and scandium BB scare me, i would like a chromo axle i would rather lose 22g of weight savings and have the stiffness and strength of a chromo axle than to save 22g. anyone with me? AC isis BB is what i am going with all the way.


I don't think your going to get less strength, and the Al BB would be stiffer because of the thicker walls I think.

The AC still isn't available :!:


thicker walls??? its an isis BB made to be a certain size of OD to fit, maybe ID is smaller (thicker) but then you could not use the same bolts, so i would disagree with that. i know the chromo axle is stronger and will outlast the alu. so i do not want to gamble with that.

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Superlite
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Joined: Fri Aug 29, 2003 9:01 pm

by Superlite

thicker walls??? its an isis BB made to be a certain size of OD to fit, maybe ID is smaller (thicker) but then you could not use the same bolts, so i would disagree with that. i know the chromo axle is stronger and will outlast the alu. so i do not want to gamble with that.


The internal diameter does not dictate the bolts size. The threads that are tapped into the axel can be made any size. It's like a smaller diameter hole is drilled into the BB, then for the treads for the bolts a larger diameter hole is drilled in, but only the total lenght of the threading needed, not the entire length.

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Ye Olde Balde One
Posts: 495
Joined: Sun Oct 19, 2003 4:26 pm
Location: Santa Monica, CA

by Ye Olde Balde One

spytech wrote:thicker walls??? its an isis BB made to be a certain size of OD to fit, maybe ID is smaller (thicker) but then you could not use the same bolts, so i would disagree with that. i know the chromo axle is stronger and will outlast the alu. so i do not want to gamble with that.


It doesn't use the same bolts, read the spindle spec. line again.

You can't know that one is stronger or will last longer than the other, no one can unless they tested both.
Ride lightly!

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spytech
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by spytech

Superlite wrote:
thicker walls??? its an isis BB made to be a certain size of OD to fit, maybe ID is smaller (thicker) but then you could not use the same bolts, so i would disagree with that. i know the chromo axle is stronger and will outlast the alu. so i do not want to gamble with that.


The internal diameter does not dictate the bolts size. The threads that are tapped into the axel can be made any size. It's like a smaller diameter hole is drilled into the BB, then for the treads for the bolts a larger diameter hole is drilled in, but only the total lenght of the threading needed, not the entire length.


but if you drill a bigger thread for the same bolts to fit then it will not have thicker walls, right?

Ye Olde Balde One wrote:
spytech wrote:thicker walls??? its an isis BB made to be a certain size of OD to fit, maybe ID is smaller (thicker) but then you could not use the same bolts, so i would disagree with that. i know the chromo axle is stronger and will outlast the alu. so i do not want to gamble with that.


It doesn't use the same bolts, read the spindle spec. line again.

You can't know that one is stronger or will last longer than the other, no one can unless they tested both.


well i know chromo will be stronger than alu and outlast it - but in this case your right a test must be done - but my money is on the AC BB or at least thier spindle/axle.

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Superlite
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Joined: Fri Aug 29, 2003 9:01 pm

by Superlite

but if you drill a bigger thread for the same bolts to fit then it will not have thicker walls, right?


Only where threading is. An aluminum axle is stiffer, which is better and worse. Better, because, well, stiffness is good. Worse, because of fatigue life. But if well design an aluminum axle can be just as good.

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Ye Olde Balde One
Posts: 495
Joined: Sun Oct 19, 2003 4:26 pm
Location: Santa Monica, CA

by Ye Olde Balde One

spytech wrote:well i know chromo will be stronger than alu and outlast it - but in this case your right a test must be done - but my money is on the AC BB or at least thier spindle/axle.


For the same amount of material, yes it will, but you can put more material in there, which is what they did. Because it's less dense, it's also lighter with more material, that extra material should actually make it stiffer, or the same stiffness, with extra strength.
Ride lightly!

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Cyco
Posts: 1903
Joined: Sat Nov 30, 2002 4:49 am

by Cyco

If the OD is constrained (as it is) then an Al tube will need to be approx 3x the wall thickness of the CrMo for the same stiffness. This will lead to them weighing Approx the same.

Is there enough room inside the Spindle for this to be the case?

I suspect the X-Long bolts on the Road Shark are there to try and prevent flex inside the splines and bearings. A grade 1 Interferance fit thread (light resistance to bolt instalation the whole time) could well act as thicker wall.

I think it is unlikly an Al spindle BB will fail, if designed correctly, but additional flex could cause premeture bearing failure, a problem already common in ISIS. A combination needle/ball would help - but add weight.
Success is how far you you bounce back up after being knocked down

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