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chain derailment caused broken and bent spokes

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chain derailment caused broken and bent spokes

Old 06-12-21, 12:49 PM
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preventec47
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chain derailment caused broken and bent spokes

Trying to skip over too many sprockets too fast caused rear wheel derailment and when the chain got wedged in between the large sprocket and spokes,
two spokes were broken and four or five bent a little. I was able to mount the chain and ride home with a wobbly wheel. Now that I have the wheel off
I am wondering if I can only replace the damaged spokes. I dont have the experience or tools to do the job so I will be taking the rim to bike shop.

This wheel was off a factory bike bought in Switzerland in 2005 and has a hub model make of ONYX by DT SWISS. picture attached. The rim is a stout
double wall rim "EXAL SP-19" in 559 size. . I assume the 9 gear cassette will have to come off and then a good spoke is going to have to be removed
to ascertain the size of replacement spokes needed. It so happens that only the spokes on one side of the wheel are damaged.... ( the sprocket side of course )
so I think the other side spokes are all good and can be left alone other than adjustments needed for alignment when new spokes are installed.

Am I understanding this mostly correctly? I know there is the rachet mechanism and bearings to think about but if the bearings are available and cheap, just replace them or otherwise just clean and re-lube.... am I right ? The question is how can I know if new components are avialable ? I need factory specs
or info related to the model of my HUB.... which I do have but I cannot find any technical info on the ONYX by DT SWISS. I assume long ago discontinued
and google search does not come up with much.

It was a stupid stupid mistake and I will never do it again. I tried to switch from probably a 17 tooth to the 34 tooth gear quickly skipping over too many and
it threw the chain right off. Normally as I approach a steep hill I downshift while spinning and coasting but this time I forgot.

Is the bike shop likely to have spokes like I need or will they probably need to measure and special order..... Or should I do that ?


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Old 06-12-21, 01:27 PM
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Originally Posted by preventec47 View Post
Is the bike shop likely to have spokes like I need or will they probably need to measure and special order
Ask them.
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Old 06-12-21, 01:33 PM
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Replace the damaged spokes and adjust the derailleur so there is no repeat problem.
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Old 06-12-21, 01:37 PM
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Bring the entire bike into the shop, not just the wheel. If the derailleur hanger is bent, which is highly probable, the shop should realign it to reduce the likelihood of a repeat of the derailleur-into-spokes incident.
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Old 06-12-21, 03:07 PM
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This is the reason for a spoke protector. A fast spinning downshift can cause a chain dump regardless if the der. is properly adjusted or not.
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Old 06-12-21, 03:15 PM
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A spoke protector would not help unless it purely filled up the space between the sprocket and the spokes. The reason for the damage is the space existing
is too narrow for the chain to slide down between the spokes and the sprocket. and when I peddeled, it forced the chain down in between like a hammer and
wedge breaking the spokes. I could envision another sprocket without any teeth that was slightly larger to keep the chain from coming off the last biggest sprocket
I am not aware of anything like that existing ? ? ?
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Old 06-12-21, 03:21 PM
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You probaly need to replace all the outer spokes. If you have 36 spokes that means 9 spokes. I destroyed my wheel that way last week thanks to badly adjusted real deraileur. My mistake
Bike shop fixed the wheel and now it's good again. I did not ride the wheel tho I walked the bike home.

I'd buy a dork disc but no one has one for sale.
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Old 06-12-21, 03:24 PM
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Use a bike shop that has a decent wheel person. It'll be easier, they might figure out why your chain came off even though you seem to blame your rapid shifting. I don't blame you on that, I grab multiple gears quickly on my bikes and don't have that issue.

Your wheels might need some attention any how just to have spokes readjusted properly and add back any true you might have lost over the years.
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Old 06-12-21, 03:34 PM
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Originally Posted by Ihmemies View Post
I'd buy a dork disc but no one has one for sale.
Are you joking ? or is there such a thing as a dork disk ? I do have something like that for my front triple sprockets that blocks the chain from coming off
the big sprocket.
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Old 06-12-21, 03:39 PM
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Originally Posted by Ihmemies View Post
I'd buy a dork disc but no one has one for sale.
Look up 'spoke protector' - many available
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Old 06-12-21, 04:27 PM
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That hub takes standard spokes. A shop will just measure the thickness and length and replace the damaged ones with similar. (I doubt all the spokes of that side need replacing unless you actually did scratch/gouge them all.)

Do have the hanger looked at for alignment. They rarely survive this staying straight. The derailleur also usually takes a hit when this happens. Sometimes it can be bent back or the damaged half lifted off another derailleur.

A fast shift shouldn't do this. Still, now you know the consequences. I set my derailleur limit screw so that it just shifts reliably on to the big sprocket, no more to keep this from happening. (And I do this riding the bike. not on a stand.) It looks like you got off fairly lightly. Take this as a learning experience. You can injure yourself and destroy frames doing this. (And a dork disc might have stopped this. Might have had just enough push to keep the chain from falling off. I cannot say from first hand experience. I've never bought a bike that came with one - and in my younger days, it would have been the first thing I would have taken off.)

Last, welcome to the club! (Rather large membership but many are quite secretive about it.)
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Old 06-13-21, 08:35 AM
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Originally Posted by VicBC_Biker View Post
Look up 'spoke protector' - many available
You just need to select the correct one for the number of spokes you have so that the mounting clips fall between the spokes correctly.
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Old 06-13-21, 12:34 PM
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Originally Posted by 79pmooney View Post
That hub takes standard spokes. A shop will just measure the thickness and length and replace the damaged ones with similar. (I doubt all the spokes of that side need replacing unless you actually did scratch/gouge them all.)

Do have the hanger looked at for alignment. They rarely survive this staying straight. The derailleur also usually takes a hit when this happens. Sometimes it can be bent back or the damaged half lifted off another derailleur.

A fast shift shouldn't do this. Still, now you know the consequences. I set my derailleur limit screw so that it just shifts reliably on to the big sprocket, no more to keep this from happening. (And I do this riding the bike. not on a stand.) It looks like you got off fairly lightly. Take this as a learning experience. You can injure yourself and destroy frames doing this. (And a dork disc might have stopped this. Might have had just enough push to keep the chain from falling off. I cannot say from first hand experience. I've never bought a bike that came with one - and in my younger days, it would have been the first thing I would have taken off.)

Last, welcome to the club! (Rather large membership but many are quite secretive about it.)
Please stop calling it a dork disc.
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Old 06-13-21, 12:40 PM
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Originally Posted by davidad View Post
Please stop calling it a dork disc.

Agree.
'Brifters' are OK with me, but not 'dork disk'.
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Old 06-13-21, 12:54 PM
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I call them dork disc's. I even called them that when I owned and rode bikes with a dork disc for some 40 odd years. What's the deal?
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Old 06-13-21, 12:57 PM
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Originally Posted by davidad View Post
Please stop calling it a dork disc.
Probably not going to happen. But you will also not hear me saying that those who use the discs are the dorks.
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Old 06-13-21, 12:59 PM
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Originally Posted by Iride01 View Post
I call them dork disc's. I even called them that when I owned and rode bikes with a dork disc for some 40 odd years. What's the deal?
Best to use Proper part names when conversing with REAL Mechanics.
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Old 06-13-21, 01:21 PM
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Originally Posted by 10 Wheels View Post
Best to use Proper part names when conversing with REAL Mechanics.
So brifters are out too. I never cared for that term and don't use that.

I like the little blurb in wikipedea for Shimano Total integration, hover your pointer over the citation needed at the end of the first paragraph.

while often used on ******, no one that has a clue about bikes calls them this (June 2020)
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