Derailer

[Help.Me.]

Hi all.... I did a road race yesterday and halfway through the race when shifting gears,the big front blade to the smaller one, my back derailer got caught in the spokes and broke the derailer hanger. This was now the second time. Is this an operator problem ?? The chain was on the middle blade on the casette. After the first incident at Knysna i am very cautious when shifting and still it happened? Any advice/help will be appreciated

[kosmonooit]

Possibly chain length?

[Dustbin Dog]

Hi all.... I did a road race yesterday and halfway through the race when shifting gears,the big front blade to the smaller one, my back derailer got caught in the spokes and broke the derailer hanger. This was now the second time. Is this an operator problem ?? The chain was on the middle blade on the casette. After the first incident at Knysna i am very cautious when shifting and still it happened? Any advice/help will be appreciated

 

Hi HM my experience is the only time your derailleur can get into your spokes is if the mechanical stop screw is not correctly adjusted. Check to see if the pivot bush of the derailleur is not worn and that all is fastened as it should be. Good luck.

[Scooterza]

Argghhh - I had typed a good long explanation but lost it when my laptop suddenly died. So in summary:

1. Your maximum and minimum shift screws on your dérailleur need to be adjusted. This limits how far "inwards" your dérailleur can move and prevents just such a thing from happening. Google "adjust rear dérailleur" for full details.
   
2. One of your spokes is bent and/or your rim is flexing, enough to cause your dérailleur to catch a spoke. Perhaps on a bike clamp, when there is no stress on your rear wheel, this doesn't happen but once you are on the bike, the weight causes a fractional movement of the rear wheel relative to the dérailleur - enough that the dérailleur can get hit by a spoke.
   

[Help.Me.]

Hi HM my experience is the only time your derailleur can get into your spokes is if the mechanical stop screw is not correctly adjusted. Check to see if the pivot bush of the derailleur is not worn and that all is fastened as it should be. Good luck.

 

Thanks , you reckon the LBS did not do a proper job when replacing the first derailer? My cycling buddy noticed that the chain runs very close to the spokes when we fine tuned the gears , but that was just after the LBS changed the derailer ??

[EigerSA]

This has happened before? So it's a new dérailleur then? I would definitely have words with the person who fitted it then. Best advice... listen to what fate is obviously trying to tell you and ride single speed

[Help.Me.]

This has happened before? So it's a new dérailleur then? I would definitely have words with the person who fitted it then. Best advice... listen to what fate is obviously trying to tell you and ride single speed

 

Must admit the thought did cross my mind ...... we made a fixie to finish the race fortunatly we did all the hills in the first part!! Chain kept coming of or jumping to a smaller blade, a friend(mad person) "insisted" he will take my bike and i must take his to finish the race. Which we then did(is this legal ?? any way it was just DC training for us) My friend stopped on route got a piece of wire and made a contraption to keep the chain in place!!!! Will post pics later.... What a day

[Eugene]

Have you had a fall recently. A bent hanger or derailure could cause the same problem

[Help.Me.]

Have you had a fall recently. A bent hanger or derailure could cause the same problem

 

Hi Eugene....not with this bike but with the mountain bike yes

[Christopher Brunsdon]

Sounds like you need a new LBS.

[LeTurbo]

So the lbs replaced the derailleur, but you and your buddy fine-tuned the gears? And that's when it seemed to run close to the spokes? Hmmmmmmmm ...

[Help.Me.]

So the lbs replaced the derailleur, but you and your buddy fine-tuned the gears? And that's when it seemed to run close to the spokes? Hmmmmmmmm ...

 

The chain on the casette runs very close to the spokes.... it was just an observation.We did not fiddle with anything except the cables....

 

I am actually a mountainbiker but got bullied into doing the DC so i have done about 500 km on this roadbike, knysna 100km where the first breakdown occured and then 100km in PE yesterday, the other 300 km was training rides with no problems...i am

[bikemonster]

 

halfway through the race when shifting gears,the big front blade to the smaller one,

 

my back derailer got caught in the spokes and broke the derailer hanger

 

The chain was on the middle blade on the casette

 

I've edited your post to make things clearer.

 

You weren't even changing gears on the wheel, is that correct?

 

And you were in the middle gear on the cassette, at the wheel, correct?

 

If both of these questions are answered with "Yes, that is correct!", then there was something very wrong. No amount of limit screw adjustment would have helped. Either the derailleur was bent, or the hanger was bent. I don't see any other way the wheel could have eaten the derailleur, as you weren't changing onto the largest sprocket on the cassette.

[Help.Me.]

I've edited your post to make things clearer.

 

You weren't even changing gears on the wheel, is that correct?

 

And you were in the middle gear on the cassette, at the wheel, correct?

 

If both of these questions are answered with "Yes, that is correct!", then there was something very wrong. No amount of limit screw adjustment would have helped. Either the derailleur was bent, or the hanger was bent. I don't see any other way the wheel could have eaten the derailleur, as you weren't changing onto the largest sprocket on the cassette.

 

You weren't even changing gears on the wheel, is that correct? I changed the front big blade to the small blade

 

And you were in the middle gear on the cassette, at the wheel, correct? Yes

 

Either the derailleur was bent, or the hanger was bent. This was a brand new derailleur and hanger put on the bike a month ago and i did a 97km last week Sunday with no "problem"(first trip after the repairs)

 

as you weren't changing onto the largest sprocket on the cassette. can this cause the above problem??

 

thanks for all the info the LBS has some other stories.....stone hit blade made a dent and chain shuck etc etc.

[bikemonster]

as you weren't changing onto the largest sprocket on the cassette. can this cause the above problem??

 

What can happen is that the rear derailleur can change past the largest sprocket and into the spokes, if the limit screw is not properly adjusted.

 

All the advice re: limit screws given above was based on the assumption that you were changing to the biggest sprocket.