Question about Giant ISP Saddle Mount?

Discuss light weight issues concerning road bikes & parts.
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ms6073
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by ms6073

I have a question for those of you acrosss the Atlantic concerning the saddle mount on the Giant TCR Advanced LE ISP. I currently ride a 05' TCR Advanced (Silverdream - size large) and use FSA's K-Force Seatpost with 2.5cm setback with 172.5 cranks and am concered that if I switch to the ISP framset, that additional 2.5cm setback will be lost.

Image

Above is the first closeup image I came up with while searching the web and am curious if the saddle mount atop offers more than one mounting point for the seat attachment like on the 05-06' TCR TT and TCR Trinity sear posts?
Michael - The Anaerobic Threshold is neither...

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strobbekoen
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by strobbekoen

Hi,

I have a TCR Advanced ISP 2006.
The saddle mount has 3 holes but only 1 - the middle one - has a threading for the bolt.

I measured the distance center of clamp to center of seattube, it's 1.5cm

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ms6073
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by ms6073

Thanks for the quick response and the measurement for the mounting offset. Interesting that there are 3 mounting holes but only is threaded - I wonder if that will hold true for the framesets that are imported into the US? Should have paid more attention while I was at Interbike last month - I held the frameset in my hands a number of times but did not think about this issue until this week as I am about to order our framesets.
Michael - The Anaerobic Threshold is neither...

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strobbekoen
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by strobbekoen

This is a picture of the inside of the clamp.
The first hole (on the right in the pic) is useless as it's part of the clamping space. The 3rd hole on the left has no threading, only the middle has, no idea why though!
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DSC06213.JPG

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Giantlover
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by Giantlover

strobbekoen wrote:This is a picture of the inside of the clamp.
The first hole (on the right in the pic) is useless as it's part of the clamping space. The 3rd hole on the left has no threading, only the middle has, no idea why though!

to save some weight? :lol:

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strobbekoen
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by strobbekoen

Giantlover wrote:
strobbekoen wrote:This is a picture of the inside of the clamp.
The first hole (on the right in the pic) is useless as it's part of the clamping space. The 3rd hole on the left has no threading, only the middle has, no idea why though!

to save some weight? :lol:


Maybe, too bad it still weighs 112g :wink:

geraintnorman
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by geraintnorman

strobbekoen wrote:
Giantlover wrote:
strobbekoen wrote:This is a picture of the inside of the clamp.
The first hole (on the right in the pic) is useless as it's part of the clamping space. The 3rd hole on the left has no threading, only the middle has, no idea why though!

to save some weight? :lol:


Maybe, too bad it still weighs 112g :wink:


I also have an ISP and mine is the same. Does anyone know if any manufacturers make a lighter replacement?

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strobbekoen
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by strobbekoen

Giant's been using it for years now. I assume with good reason :)
The forces on the clamp can be quite high i think.
If we consider a standard carbon seatpost of 200g, i bet the clamp also weighs around the 100g figure.

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ms6073
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by ms6073

strobbekoen wrote:This is a picture of the inside of the clamp.
The first hole (on the right in the pic) is useless as it's part of the clamping space. The 3rd hole on the left has no threading, only the middle has, no idea why though!


Now that I see that image it makes sense why the 3rd hole has no threading. Obviously the attachment/clamp design places a lot of compression force on the top of the seat mast but unlike a seat post in a seat tube, there is nothing to prevent the seat mast tube from deforming under load. If Giant threaded the 3rd mounting hole, a heavier rider using a longer saddle (Fizik Arione) while on a prolonged climb would move all the way back on the saddle and the leverage of that position would be placing an uneven distribution of force on the mast. Seems to me that if the torsional load causes the mast tube to briefly deform slightly, the intregrity of the force the clamp exerts on the mast might be compromised (especially if the rider is using the full-body climb technique :D).
Michael - The Anaerobic Threshold is neither...

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strobbekoen
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by strobbekoen

Yes that makes sense. So i guess they drilled the hole to shave a few idle grams.. I am not worried about it's weight much though.

Irish
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by Irish

You could try using a saddle with longer rails like an SLR(if you not already using one).There can be a vast difference in the amount of set back you can have even on saddles from the same manufacture(check flite v SLR).Hope this helps.

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ms6073
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by ms6073

strobbekoen wrote:This is a picture of the inside of the clamp


Just curious, could you provide me with the lengthwise dimension of that clamp form your bike - ie with a saddle mounted in the clamp, what is the length from the bottom edge of the clamp to bottom edge of the saddle's mounting rail?


Regards,
Michael - The Anaerobic Threshold is neither...

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strobbekoen
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by strobbekoen

Is it this what you mean ? I was not sure what you meant with 'bottom of clamp'. The distance of bottom of rail to bottom of clamp as pictured is 5.1cm.
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ms6073
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by ms6073

Yes - that is perfect. Thanks.
Michael - The Anaerobic Threshold is neither...

Greyham
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by Greyham

just wondering if anyone can fill me in as the maximum length of the mast for a size med? I run my saddle around 80cm's which is quite long for a medium, but i'm lots of leg and not much back, plus i like the short short head tube for maximum drop. The webber says that the length is pretty short, and i fear too short.

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