Catastrophic Failure!

ozt9vdujny3srf

So I'm cycling along, fairly chilled out, not going hard trying to accelerate or anything like that, so relatively little stress on the drive train an all of a sudden the rear derailleur just gets torn off. Pics attached

Derailleur is a few months old. Is this common? Warranty issue?


As an aside i've also had problems with the rear wheel spokes breaking recently, think i need a new rear wheel. Its a racer, any recommendations? strength is more important then weight.

ba

there is normally a 1 year warranty on parts. so bring it back to where you bought it. very unusual that it just fell off under normal stresses.

bout the rear wheel, have it sorted immediately before you lose more spokes and your rims buckle beyond repair.

kenmc

that looks like a stress fracture. very wierd that it broke rather than the rear hanger, which is supposed to be the weakest point. Should be under warrenty for sure.

Chips Lovell

Did you ever crash the bike or drop it on its right side? It could have caused a crack that gradually grew over time. If you didn't, send it back for warranty. Parts do break from time to time.

Bob the Builder

If this particular type of damage was caused by you, you would have known about it on the spot. To me, Appears to be a stress failure which will be/should be covered by it's relevant warranty.

ozt9vdujny3srf

I'll bring it in to where i bought it tomorrow and see what they say. I dropped by today after it happeded (I wasnt far away from the shop so i just carried the bike down) but they were closed for a half day today. I haven't crashed the bike, biggest hits it has taken are potholes.

The wheels: They arent expensive wheels so I was thinking of just replacing the whole wheel, although there has only ever been one broken spoke on the wheel at a time (had them replaced) so it isnt too buckled. I might just cycle on with this wheel until its knackered for now, but i'd be interested to see what kind of price a good wheel can be got for. (Low end)

doozerie

That's an odd place for it to snap. It looks to me like a manufacturing fault for the body to have snapped like that. I've only ever seen a derailleur snap at one of the hinge points before (and even then it is a rare occurence in my experience). If it has signs of ever having taken a hard knock from a fall, or similar, than the supplier might resist replacing it, but otherwise (and even if that is the case) I would hope that they would replace it without question.

As for the broken spokes in your rear wheel, I have had one hub (many years ago) where the holes drilled for the spokes were left with rough edges and this was the likely cause of spokes being broken regularly - the spokes in that case invariably snapped at the bent section where they met the hub. If your spokes are breaking at this point then the hub might be the culprit. Basically, look for patterns in the breaks and see if they might point to a particular cause, so do all of the spokes tend to break at around the same location along the lenght of each spoke, is it always spokes from the same side of the wheel, etc.? It could be very difficult to pinpoint the cause though.

Another question is whether your spokes are single-butted (thicker at one end only) or double-butted (thicker at both ends and thinner in the middle section). I was once told that double-butted spokes never break, but unfortunately I proved that not to be true - they should be less prone to breaking than single-butted or non-butted spokes though as the thicker parts are where most of the stress is exerted and so they are designed to be stronger. If you are snapping butted spokes then the problem is more serious - I'd maybe wonder whether your frame is out of alignment at the back (which might put extra stress on the derailleur too, I guess). With both wheels on the bike try to line up the wheels by eye to see if they are in the same plane - the definitive way is to take measurements but at that stage it is probably worth having a bike shop take a look as a decent shop may have the right tools to check this.

It is conceivable that root cause is that your rim is so out of whack that the pressure on the spokes is just very uneven and some spokes are under excessive stress. In that case your best bet is to replace the rim (and the spokes too as you won't want to detract from a new rim by using weakened spokes), or just replace the wheel.

cyclopath2001

Esme Happy Peach the Uncivil wrote: »

So I'm cycling along, fairly chilled out, not going hard trying to accelerate or anything like that, so relatively little stress on the drive train an all of a sudden the rear derailleur just gets torn off....
As an aside i've also had problems with the rear wheel spokes breaking recently, think i need a new rear wheel. Its a racer, any recommendations? strength is more important then weight.

No disrespect, but the term 'racer' is usually applied to cheap imitations of the road bikes used by experienced riders.

If your derailleur was incorrectly adjusted, it could have been hitting the spokes when changing to the largest sprocket. In an extreme situation, it would get caught in the spokes and you'd get a fairly messed up situation like what you've got.

Spokes snapping and all that might have something to do with how you ride (jumping kerbs?), how heavy you are and the quality of the roads you're using. Can also happen if the wheel is not well built.

If you want strength/reliability around town, a road bike or 'racer' is usually not the best choice.

ozt9vdujny3srf

Road bike so, oops! I reckon the back wheel was badly built, because i have been having problems with it since i bought the bike (from a month after) and the front wheel is perfect. Every time I went back they replaced the spokes for free but I am fed up arguing about it and dont use said shop any more. I haven't jumped kirbs with this bike, but as I said above I have hit potholes that i havent seen and given the front wheel a fairly jarring blow, but it still seems ok. The derailleur was shifting perfectly, and not clicking so i dont think it caught the spokes.

I know a hybrid might be more practical, but i love this bike!

doozerie

cyclopath2001 wrote: »

If you want strength/reliability around town, a road bike or 'racer' is usually not the best choice.

I disagree. My current commute bike is a road bike on which I have raced, trained a lot, and carried full pannier bags on many occasions. And I used standard road wheels and tyres (23c tyres 'cos my mudguards don't accommodate anything larger) throughout. I think there is a common perception that a road bike is more fragile than a mountain bike, and in some respects that is true, but I think that people often overestimate the difference.

The frames are often comparable between the two bike types, and while mountain bike wheels are inherently stronger due to their smaller diameter (and are protected from some abuse by the wider tyres) road bike wheels are very robust too. I have put a lot of demands on my road wheels over the years, and although I am small and light I have loaded the pannier rack regularly so they have carried a lot of weight. Invariably my road rims eventually bite the dust because of the sidewalls being worn out by the brake pads (which is obviously something that mountain bike rims suffers from too unless you use disk brakes) rather than because of damage due to roads etc. And I very rarely have spokes break on my either.

As for hybrids, these days a lot of hybrids are just road bikes with "straight" handlebars so they are as robust/fragile as a conventional road bike.

blorg

A road bike, presuming it is decent, will stand up fine to cycling around town, no reason at all not to use one. I do many more km on my road bike than anything else (around 4 times as much as the next nearest I reckon) and I have less trouble with it than the other ones.

On a paper thin-like similar-ish topic, I did a small bit of maintenance on my bike just there (since it refused to go into the third set of gears today) and discovered that the front derailleur was loose due to one of the allen bolts connected to the frame having gone missing and the other one being fairly loose.

That could have been bad.

Howitzer

worst catastrophic failure I had was the saddle bolts cracked in half - thankfully the saddle post only hit my inside thigh and no-where else!
sh1t happens! Hope you get somewhere with the warranty route

crashoveroid

Good old Shimano LOL

blorg

crashoveroid wrote: »

Good old Shimano LOL

Don't start a religious war here; Shimano stuff is generally pretty rock solid as I am sure you are aware.

crashoveroid

blorg wrote: »

Don't start a religious war here; Shimano stuff is generally pretty rock solid as I am sure you are aware.

Dont know about that ive seen loads of them dont like the jap Crap

Chips Lovell

No brand is immune to failures. My Record cranks broke a few weeks ago.

crashoveroid

el tonto wrote: »

No brand is immune to failures. My Record cranks broke a few weeks ago.

I know im only having a laugh

blorg

el tonto wrote: »

No brand is immune to failures. My Record cranks broke a few weeks ago.

Noooooooooooooooooooooo

Chips Lovell

blorg wrote: »

Noooooooooooooooooooooo

Thought you knew about that. I was on my way home from a spin with you. Remember the morning you were late and sprinted up Stocking Lane?

blorg

Ha yes, I remember you stole your wife's cranks for the next spin. I was merely expressing my incredulity that Campy could break, never mind Record :eek:

Those cranks are rebuildable you know, one of the major advantages over Shimano

Chips Lovell

blorg wrote: »

Ha yes, I remember you stole your wife's cranks for the next spin. I was merely expressing my incredulity that Campy could break, never mind Record :eek:

Those cranks are rebuildable you know, one of the major advantages over Shimano

Still have the wife's cranks. It's proving a pain in the ass to get them warrantied and may take another few weeks.