Giant Propel SL Top Tube Crack. Is it too fragile?

Discuss light weight issues concerning road bikes & parts.
ToffieBoi
Posts: 418
Joined: Fri Jan 31, 2014 4:54 pm
Location: Krakow, Poland

by ToffieBoi

Hello everyone,

This morning, around 6am I woke up with the worst sound ever. My cat decided to knock off my bike during her morning routine, and my bikes top tube was able to meet with the corner of my bedframe. BANG. Not 2cm higher on the bed, not 2cm lower and all the way to the ground. I don't know if there are anyone was able to break anything that stupidly on their bikes... Maybe I should start a Bike Darwin Award topic. Anyways...

I checked the top tube carefully and around the end of the tube, there is a small impact mark and the top of the tube has a thin, long crack. I will be checking for carbon repair shops around here and maybe sell the frame cheap and totally get rid of it... I took some photos and tried the show the marks. I wonder if I should risk it for a bit and ride like this, until getting a new frame? Would you ride this? I also wonder if anyone has experience with top tube cracks, does it worth the risk of fixing it or I shouldn't bother at all.
DSC06014.jpg
DSC06015.jpg
DSC06017.jpg
But main reson I started this thread is, I wonder if this is a really common issue with Propel SL's.

I don't know many people with the Propel SL frame, actually only 2 of my friends, and this is the 3rd cracked top tube in the group. A friend had a crack there after a crash. Second friend had a similar situation where his frame fell down on the shop, hitting the guy on the head. Cracked top tube... (Okay maybe this is better for Bike Darwin Award). Because there was no impact mark, Giant replaced the frame on warranty. I purchased that frame, and here we are around a year later...

Karvalo
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by Karvalo

It's not a specific issue with Propel's, but light or high-end bikes in general that top tubes are vulnerable. They're probably the least stressed area of the bike in normal riding conditions, so naturally have very thin walled tubes. A few years ago there was a trend of climbing bikes with such thin tube walls that you could easily flex the surface of a TT with finger and thumb pressure.

by Weenie


GothicCastle
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Joined: Mon Jul 04, 2016 1:52 am

by GothicCastle

Carbon tubes are only strong in tension. A hard knock, particularly with a sharp edge, can easily crush a thinner tube.

sharkman
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Location: the Netherlands

by sharkman

Think that probably every carbon frame would crack after the point impact you described. Only thing this topic proves is that Giant has a good guarantee even after less than honest claims from customers


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ToffieBoi
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by ToffieBoi

sharkman wrote:
Fri Nov 02, 2018 6:09 am
Think that probably every carbon frame would crack after the point impact you described. Only thing this topic proves is that Giant has a good guarantee even after less than honest claims from customers Image

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Giant knew exactly what happened to the frame. I really don't think there is lack of honesty once all the information is there ;)

Anyways, I was sure that it cracked once I saw how the bike is leaning on the bedframe. But since it is now that the every Propel SL frame I know is cracked at the same place, I thought maybe this frame is weaker than few others out there.

eric01
Posts: 646
Joined: Mon Feb 06, 2006 1:06 am

by eric01

High end carbon frames are optimized for pedaling forces and light weight. The whole laterally stiff, vertically compliant at the lightest weight thing. Material is removed where it isn’t necessary.

They aren’t optimized for withstanding bed post impact or falling on people’s heads.
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efeballi
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by efeballi

My worst nightmare as a Propel owner.
Have you tried the coin test?


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2015 Giant Propel Advanced
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ToffieBoi
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Location: Krakow, Poland

by ToffieBoi

efeballi wrote:
Fri Nov 02, 2018 2:07 pm
My worst nightmare as a Propel owner.
Have you tried the coin test?


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As many other wise people tells here, don't let your cat drop the frame on the bed or on your head... Rest should be alright :D
I did and actually sound does not change at all...

Sock3t
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by Sock3t

That's an expensive cat.

efeballi
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by efeballi

ToffieBoi wrote:
efeballi wrote:
Fri Nov 02, 2018 2:07 pm
My worst nightmare as a Propel owner.
Have you tried the coin test?


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As many other wise people tells here, don't let your cat drop the frame on the bed or on your head... Rest should be alright :D
I did and actually sound does not change at all...
Have it checked somewhere (I honestly don’t know where) but don’t bin the frame just yet IMO.

My Propel is 1800 km away from me and God knows what it’s going through...


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SHUT UP LEGS
2015 Giant Propel Advanced
2015 Cannondale Supersix Evo
2013 KTM Strada mod. (totaled)
2011 Pinarello Dogma 60.1(loaner)
2011 Scott SUB 45(sold)

Politecnico di Milano Ingegneria Meccanica

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Calnago
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wheelsONfire
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by wheelsONfire

I looked at a video-clip from Factor. They showed it's common frames suffer cracks at seatstays.
Factor now design theirs to handle impact.
Not sure, but it seems they're pretty much one of few doing this?
Light weight sure is adding to risks. It would be interesting to see if higher stiffness grade carbon is more prone to suffer from cracks, than a lower grade.
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sharkman
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by sharkman

Can’t see the point in this. Frames shouldn’t be designed for freak accidents (your bed post but also the other post of a chestnut ending the life of a caad 12)
A brand mentioning they focus on a weak point of other brands try to create a Unique selling point to justifiy their higher price by appealing on customers fear others probably do the same to reduce guarantee claims and don’t brag about it.
Giant top tubes of the carbon pro frames are reinforced since the early days since a lot of them cracked because the riders tend to use them as Seats before/after the races.


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ToffieBoi
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by ToffieBoi

Sock3t wrote:
Fri Nov 02, 2018 4:16 pm
That's an expensive cat.
Little lady :noidea:
Calnago wrote:
Fri Nov 02, 2018 5:21 pm
Image
Actually she looks nothing like that :unbelievable:
Pietruszka.jpg
Reinforced frame parts can be a good sales point. Not everyone is just racing, for most of us bike is a tool that we daily use.
CAAD12 example is the best reason why this topic has a point. Chestnut impact is something normally shouldn't damage the frame. Because everyone agrees that, and many other easily dented CAAD12 top tubes, everyone knows that those bikes have more fragile TT than many other around. There are logical reasons behind, no-one says it is a bad thing but it is a fact.
Since this is the third cracked TT I've seen on Propel SL frames, similar kind of information that I am not aware of might exist; and here I am, looking for it.

sharkman
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by sharkman


There might be a point in this, but i service about 20 propel sl’a and have seen no cracks a all (in the top tube)
Most other problems can be solved. Seen warranty issues with bad fitting bottom brackets, headset top bearings and crooked brake guides but Giant has been superb with their warranty. Only real design fault with the customer propel are the carbon rear drop-outs that wear way too early (the pro frames have these made from aluminium which is better but comes at a weight penalty)

A more bullet proof frame should be possible (in fact most carbon frames allready are compared to previous lightweight frames) but all comes at a weight panalty and since this is weight weenies, i tend to choose for lighter and accept the downsides that comes with that choice.


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by Weenie


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