Giant Defy 2015 - Skinny seat stays a problem?

Giant Defy 2015 - Skinny seat stays a problem?

Postby Machoman121 » Sun Aug 24, 2014 10:44 am

I'm riding a Giant Defy Composite 2 - had it for like 7 months now. It's a truly great bike - light and comfortable - I love the geometry (tall headtube, long wheelbase) - it's super stable for me. I had not wanted a twitchy roadie.

I'm toying with the idea of getting a 2nd bike (pls don't tell wifey yet). I'm drooling over the new 2015 Defy. I love the beefy head tube but am a bit concerned about those really very skinny seat stays. They looked fragile - like it could easily break or snap. Any opinions in regards to that? I remember the Giant Anthem's Alu frame (the 29er version) had a bit of reputation of breaking at the top tube-seat tube junction - when u look at that area you can see how it's much thinner/smaller that portion is. The newer Anthem has now more material in that area.
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by BNA » Sun Aug 24, 2014 11:18 am

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Re: Giant Defy 2015 - Skinny seat stays a problem?

Postby Cmm » Sun Aug 24, 2014 11:18 am

I have ordered a 2015 defy already can't wait for it to arrive! I have a feeling that although they may be skinnier the walls can be made thicker and still weigh the same as the older bigger style if that makes sense? I am assuming you are looking at the advanced or advanced pro models?
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Re: Giant Defy 2015 - Skinny seat stays a problem?

Postby Duck! » Sun Aug 24, 2014 11:24 am

Very different type of stress in the zone that tended to break in the Anthems - you had the rider's weight on the seatpost cantilevering back & basically pulling that joint apart (welds, even after heat-treating are always a slightly weaker area).
The seatstays take the load virtually along the length of the tube, and it all in compression, so there's none of that kind of stress.

Carbon also has very different properties to aluminium; it is vastly more "elastic" (it flexes more & springs back), and does not fatigue at all if stress does not exceeed its elastic limit. You' have to subject it to a pretty massive hit to exceed its yield point. You'll also find the stays are quite flat in vertical profile; this allows them to behave basically like a leaf spring, enhancing the frame's bump absorption.
I had a thought, but it got run over as it crossed my mind.
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Re: Giant Defy 2015 - Skinny seat stays a problem?

Postby Machoman121 » Sun Aug 24, 2014 5:51 pm

Hi Duck, you are right about the causes of the Anthem's seat/top tubes joint stresses. As it's a full-sus more riders tend to sit through hits thus on the down stroke the weight of the rider is actually pulling the seat tube away from the top tube. There's no seat stay to stop it. So this might not be an issue with the skinny seat stays of the 2015 Defy :D

Saw the 2015 advance 2 model at LBS today - the one with 105 and non-hydraulic disc brakes. It was a large size. Picked it up and thought - hmmm....just a touch of heft to it. Picked up the 2014 Advanced (small size) and thought - wow this is light!

I think to justify getting the new 2015 Defy over my current Defy - i'll have to stretch for the Di2 and hydraulics - at least i can see there's 2 positives. Of course it would be great to get that integrated seat post too to maximize weight and the vibration absorption but it would probably cost too much.
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Re: Giant Defy 2015 - Skinny seat stays a problem?

Postby Calvin27 » Sun Aug 24, 2014 6:18 pm

Do you really care if your giant frame breaks 1 or 2 years down the track?

Giant will just give you a new frame and then you will have the latest season colours. They are pretty good with warranty.
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Re: Giant Defy 2015 - Skinny seat stays a problem?

Postby Duck! » Sun Aug 24, 2014 6:25 pm

Machoman121 wrote:Saw the 2015 advance 2 model at LBS today - the one with 105 and non-hydraulic disc brakes. It was a large size. Picked it up and thought - hmmm....just a touch of heft to it. Picked up the 2014 Advanced (small size) and thought - wow this is light!

Giant claim that there is zero weight gain for a given model between the '14 & '15 models, even with the addition of disc brakes. Frame layups and tube profiles have been (apparently) tuned so there is still strength where it's needed, but less material in areas where some flex is desirable for comfort aspirations, for overall less frame weight. Disc brake-specific wheels have lighter rims, which offsets the slight increase at the hub.

That's what they claim, I haven't yet had a chance to put them on the scales & compare properly.
I had a thought, but it got run over as it crossed my mind.
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Re: Giant Defy 2015 - Skinny seat stays a problem?

Postby Mulger bill » Sun Aug 24, 2014 11:03 pm

Disc brakes put different loads on the stays compared to rim brakes, I'm sure Giant have taken this into account :D
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Re: Giant Defy 2015 - Skinny seat stays a problem?

Postby Scott_C » Tue Aug 26, 2014 9:34 pm

A little bit off topic but does anyone know if Giant has published maximum rider weights for the 2015 Defy's?
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Re: Giant Defy 2015 - Skinny seat stays a problem?

Postby harmonix1234 » Tue Aug 26, 2014 9:41 pm

I don't think giant advise weight limits on any of their frames. Duck would be the one to ask.
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Re: Giant Defy 2015 - Skinny seat stays a problem?

Postby Duck! » Tue Aug 26, 2014 11:49 pm

Giant don't specify a maximum rider weight.
I had a thought, but it got run over as it crossed my mind.
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Re: Giant Defy 2015 - Skinny seat stays a problem?

Postby bundydave » Tue Sep 02, 2014 6:52 pm

If its of any benefit O/P i picked up my 2015 Advanced 3 yesterday, first brand new roadie and to say i'm impressed is an understatement! Mind you i'm coming from a too small 15yo bike so it was bound to be good.
Little disappointed however at the braking and gear cables and the mess at the front of the bike being Tiagra gearset, but as that is only a cosmetic thing and that's my only gripe its not all that bad. :D
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Re: Giant Defy 2015 - Skinny seat stays a problem?

Postby Cmm » Tue Sep 02, 2014 7:51 pm

Nice choice bundy! I pick my pro 2 up this week or next when it arrives! Can't wait!
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Re: Giant Defy 2015 - Skinny seat stays a problem?

Postby Cmm » Sun Sep 07, 2014 6:37 am

Picked up my pro 2 on Friday and went out yesterday after riding a few high end giants this year (propel sl and tcr sl) I was greatly surprised by the ride quality of the defy! It was stiff in the right places for me the average joe but the biggest thing I noticed was how smooth the ride was compared to the propel and tcr (especially the propel) I know one bike is set up stiff as can be and the other is a comfort bike but my 2012 defy advance was no where near this smooth!
5800 worked nicely (comparing to 9070, 6870, 6800, 9000 ridden this year) its a little clunky and not as smooth as 6800 but was still quite nice to use.
Disc brakes felt really nice did the decent from sassafras to ftg and felt very confident in the brakes modulation and power makes me wonder if hydro would be a worthy upgrade in the future.
All in all (more testing to come) I am extremely happy with the first impressions especially the quality of bike for the price!
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Re: Giant Defy 2015 - Skinny seat stays a problem?

Postby Cmm » Sun Sep 21, 2014 6:25 am

I have ordered a set of narrow nobby tyres to see how much clearance the skinny stays and no rim brake allow. Will post pics of how it matches up :)
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