black'n'yellow
Guest
mainly torsional on the l/h, torsional and axial loading on the r/h...
Snapped Chain Stay Roubaix SL2
- Thread starter WindyRob
- Start date
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mickle
innit
- Location
- 53.933606, -1.076131
'That enormous'?
The load imposed by a too-tight chain will have an effect on bb and wheel bearings, chain ring bolts and cassette sprockets, the chain, stays, bb shell and drop-out. But it'll not load the hanger or the mech beyond their design parameters. Replaceable hangers are designed to fail when a bike is dropped or otherwise bashed on its mech - to protect the mech and frame - not to allow for the consequences of a too-short chain.
mickle
innit
- Location
- 53.933606, -1.076131
Not to replace it shurely.
mickle
innit
- Location
- 53.933606, -1.076131
What is 'that bloody tight'?
black'n'yellow
Guest
sorry, that's not entirely accurate. The hanger is designed to fail in a situation which would otherwise result in a bent chainstay/seatstay/dropout, or busted mech - and that could include chain/transmission related issues, as well as impact damage. I've replaced plenty of bent hangers on bikes which have not been dropped or crashed, but have suffered transmission failure. It's the reason why the hangers on most aluminium or CF bikes are made out of relatively low grade ally, or why the dropouts on good Ti frames are made out of CP titanium rather than the 3AL/2.5v stuff that the rest ofthe frame is usually made from. It's entirely reasonable that the hanger should have failed first, in the situation described by the OP.
In any case, we are all just speculating, because it's not completely clear what actually happened.
mickle
innit
- Location
- 53.933606, -1.076131
Sorry but it is entirely accurate. I'm not guessing, I know. And, from the OP's account, it's pretty clear to me what actually happened.
oldfatfool
Guru
If the chain was long enough to go around the relevant gears with a normal gear change and allow them to turn there would be no more or less force exerted than usual, the only force that is being applied above that of the rider is the spring in the rear deraileur. To exert any greater force would require the chain to jam whilst a force was being applied to the crank.
Given that the bike is designed to be ridden by a pro rider exerting a burst of 1000 watts+ an amateur riding will not get anywhere near this, so even an extended period of excessive spring pressure should get nowhere near the tolerances of the frame
Out of interest how many carbon riders have had a chain jump off and jam, did your frame instantly disintegrate?
Given that the bike is designed to be ridden by a pro rider exerting a burst of 1000 watts+ an amateur riding will not get anywhere near this, so even an extended period of excessive spring pressure should get nowhere near the tolerances of the frame
Out of interest how many carbon riders have had a chain jump off and jam, did your frame instantly disintegrate?
MacB
Lover of things that come in 3's
- Location
- Farnborough, Hampshire
I don't quite understand this, wouldn't it need to be significantly tighter than a Fixed or SS setup to produce an actual destructive force?
Assuming chainlength was the problem then all combos would have worked fine bar big/big. But as soon as you moved to that combo the resistance would have been tremendous, if the chain were short enough to create this problem. That's assuming it could even get into that combo in the first place.
Assuming chainlength was the problem then all combos would have worked fine bar big/big. But as soon as you moved to that combo the resistance would have been tremendous, if the chain were short enough to create this problem. That's assuming it could even get into that combo in the first place.
black'n'yellow
Guest
Well, I'm not 'guessing' either and how do you know, exactly..? And why is my own experience of replacing bent hangers less relevant than yours? Clearly you also have some other kind of unique insight into the OP's frame failure, because the OP simply says that the 'chain stay snapped' while giving no indication of where, or in what pattern the damage occurred. That's hardly a clear picture....
martint235
Dog on a bike
- Location
- Welling
Well no. I'm really no expert at this so don't know why I got involved but the way I see it is that regardless of the length of the chain an amount of pressure has been applied to the chain between rear cog and front chainring with the effect of trying to "drag the rear wheel" forward. If this has caused the chainstay to break then it suggests the frame is faulty surely.
I'll get back in my box now.
OP
OP
WindyRob
Veteran
- Location
- On the doorstep to the Southdowns
I've just emailed Geoff to see if he has any photos of the frame and the damage. If he does i'll post them.
Thanks
R
Thanks
R
OP
OP
WindyRob
Veteran
- Location
- On the doorstep to the Southdowns
OP
OP
WindyRob
Veteran
- Location
- On the doorstep to the Southdowns
i have just spoken to the chap who's bike this happened to. He is a little nervous that a deal that specialized have offered him might be withdrawn. The factory hasn't been able to replace for free given the way the damage was caused but as a good will they have offered a deal that he would like to accept and wouldn't want that to be retracted because of any negative publicity on this forum.
I'll try to have the thread removed. But until that time this is to put it on record that specialized haven't screwed him over, and that the guys in the specialized shop have actually been really good to him not only over this but in the assistance they gave him prior to the ride.
I'll try to have the thread removed. But until that time this is to put it on record that specialized haven't screwed him over, and that the guys in the specialized shop have actually been really good to him not only over this but in the assistance they gave him prior to the ride.
mickle
innit
- Location
- 53.933606, -1.076131
Why on earth would you want to remove the thread?
