Hollowgram SI vs. Hollowgram SI SL?

Discuss light weight issues concerning road bikes & parts.
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thue
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by thue

Hi, ww's

I will soon start to build my new Caad 9. I have most of the parts, but I need a crank.
Hollowgram would be the natural choice. But there are two versions to choose; SI Alu and SI SL Alu. Some who know the weight difference between these two crank arms? (Or know the actual weight of any of them)?

Regards,
Thue

by Weenie


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STARNUT
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by STARNUT

I want to say the difference is 60 grams. The SISLs are around 580 grams with a 130 BCD and BB.

Starnut

Edit: I'm a jackass. The SIs are ~ 660 grams and the SISLs are 580 grams (all in) so it's like 80-90 grams lighter depending on BCD. Considering a 7900 crank is ~660 and the BB is 90 grams, they're friggin' light.
Last edited by STARNUT on Sun Jan 31, 2010 5:29 pm, edited 3 times in total.
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topflightpro
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by topflightpro

I was told by a Cannondale demo representative that Cannondale was able to reduce the weight of the SI SL by taking away some of the metal and mass at the end of the crank arm, beyond the pedal.

This was at the end of 2007, when Cannondale was just rolling out the first Super 6's, and looking at the SI SL vs. the SI, I couldn't see a difference.

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STARNUT
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by STARNUT

It's very subtle on the outside. There is a substantial amount of extra machining on the inside of the arms, the crank bolts and lock ring are different (all are lighter). The arms are/were not the only piece that lighted up the whole crank setup. Additionally, they actually added material near the pedals to maintain stiffness (see the cartoon below).


Anyway, here's an SI

Image

Notice the crank bolts are solid...............

Image

while these are hollow.......... yes I am fully aware those are mountain cranks. They are however, the same crank bolts and crank arms used on the road bikes.

Here's an SISL

Image

here's the spider to arm interface. The SI is silver and the SISL is black. Notice the SL are missing the material.

Image


Like on MTV cribs, this is where the magic happens

Image

Since the pic was taken by a D-bag at a 100mph it's 'kinda blurry. For those that are less visually inclined, here's a pretty cartoon to illustrate the CNC wizardry at work on the SISL.

Image
Image

Starnut


Edit: some of these pics really suck :lol: but you get the idea.
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LegalizeMyCAAD9
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by LegalizeMyCAAD9

Also the lockring on the SI SL is lighter than on the SI ones!

eric
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by eric

25% more hollow!

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STARNUT
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by STARNUT

LegalizeMyCAAD9 wrote:Also the lockring on the SI SL is lighter than on the SI ones!


Yep, that's what I said. Along with the crank bolts. The Mark V rings were lighter than the Mark IV also but thats a bit thin for this discussion.

Starnut
"Don't pedal harder, pedal faster!"
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Pintxo
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by Pintxo

Then it is possible to machine the SI crank arms for the outside , no?

Pintxo
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by Pintxo

And perhaps it could drill the arms and spyder as in this picture?
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STARNUT
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by STARNUT

Machine them for the outside? I assume you mean machine them outside as well? I think we have an ESL issue here.

where'd you get that pic??

I bet the next generation of the SISL will be a DS or NDS spindle integrated into one of the arms and made from one piece of Mg or Al. I'd think what's holding them back currently is the inherent upside(s) of the current SISL. I know they have the ability to make the thing already. They make the wicked light lefty stems with the machine as it is. From a production standpoint they are able to use them (the current SISLs) on their mountain and road bikes with different spiders and spindles. The 2 piece setup would be great for road. They'd likely have to make a purpose built mountain frame that would have a narrower BB than anything currently out and the frame would be limited to that crankset. The new Flash bikes are BB30 only and are selling well so it wouldn't surprise me if they made did it that way.

Starnut
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Q-FACTOR IS A RED HERRING

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Pintxo
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by Pintxo

It's an idea drawn in 3D. The rotor of Sastre they had a machine drilled of this type.I don,t think it lose much rigidity.
I speak English very bad sorry

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by Junior Varsity

ah, now I am a d-bag? I will remember that.

Also, Sastre's cranks were solid before they were drilled out. The SiSl are hollow because they are formed with two pieces (clam shell). The walls are so thin that drilling them would not be healthy.
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Pintxo
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Joined: Mon Dec 28, 2009 9:57 pm

by Pintxo

Probably the drilled is very dangerous but the outside machined of SiSL I think it is posible at the SI
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JN2Wheels
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by JN2Wheels

Building up my first cannondale (caad9), and I picked up a pair of hollowgram si cranks. The info here on the si to sisl differences is fantastic, but I'd like to know about compatibility between the two. Specifically, are the sisl crank arm bolts, with their lovely lighter hollow soul, compatible with an si crankarm-spider-spindle setup? How about using an sisl spider on an si crankarm-spindle setup? Are the bearing shields the same?

I've poured through the Cannondale site, and all I can find is a pdf instruction sheet for the sisl, which mentions that the si version uses 8mm crankarm bolts to the 10mm sl. But that says nothing about the ext. diameter of the threading and the profile of the fit.... Or any other differences. But the document is titled SISL, so it is probably not intended to cover the si version completely.

So, I'm hoping some of you wonderful cannondale experts can welcome me to the family with a little schooling on the cross-compatibility between these two version!

Thanks, all.

-JN

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STARNUT
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by STARNUT

All SI and SISL parts play well with one another. All the spiders work on both versions, the bearings are the same size, and the spindles are the same size. There was a very slight change made to the SRM specific BB in late 2008 or early 2009. The stopped making a spindle that was 104mm for the SRM and instead sell them with the standard 103mm spindle and an NDS bearing shield that has been milled out enough to allow the collar to sit 1mm inside the shield to get the correct offset. Nothing major.

To mix and match you need to buy the tools; KT012 and KT013 are the cannondale part numbers. Those are the crank arm removal tools and the spider lockring removal tool.

Starnut
"Don't pedal harder, pedal faster!"
Q-FACTOR IS A RED HERRING

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by Weenie


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