Derailleur Damages.....

[Richard A Thackeray]

Bugger

This happened on my ride to work yesterday dinnertime
I was just exiting a roundabout too, thankfully not too busy, as it was rather an undignified (& rapid) stop!!
Aberford Road, at the junction with Bar Lane, if anyone knows Wakefield

I didn't take a photo of it, in the immediate post-incident, as I'd had to pull the chain out from between the cassette & spokes & my hands were too grotty to open a pocket & get my phone out

It wasn't due to a derailleur hitting the spokes, as I was on the 4th (or 5th) sprocket

All I can assume is that, for some reason, the lower jockey-wheel bolt dropped out, & the chain 'swung' into the spokes, taking with it, the cage, which then moved over, as the chain tensioned??
The lower-bolt has a habit of working loose, but if it's fully tight, the jockey-wheel might as well be siezed
It was due for its fortightly check-over today, or tomorrow..... Sods Law invoked itself

From it happening, it was only 50yards into the Hospital grounds
Embarrassingly, before entering the building, I had to ask a Paramedic crew (that I knew....) to unzip my chest pocket & take my mask out, or I'd have made a grotty mess of my jacket, with oily hands

Inside the building I found that 'Clinell Wipes' are surprisingly effective at removing grease/oil from hands , & almost as good as swarfega, mixed with Vim)

Damage;
Derailleur; as seen
Chain; bent & twisted at two points
Sacrificial hanger; sheared (ordered new one, yesterday at 23:30, from Ribble)
Cable; shredded
Wheel; out of true, 2 spokes snapped at hub


As stated above, new hanger ordered & email received to notify me of despatch!
I've taken the derailleur off my old (disused) Ridley (not moved for 6 years+)
Chain; I bought a couple of new ones, from Decathlon, not too long ago, so not a problem

Wheel; 'the biggie'...............
1. I could have it respoked, but the freehub has play in it, & may have been further damaged by the chain 'forcing' its way behind cassette?
2. There's substantial play in the rear bearings (press-fits)
3. If I take those points into consideration, it may be almost as cheap to buy a new pair of wheels??


However........... a few pages/search-terms has found me a rear Aksium wheel (as a 6-bolt), so that' been ordered, as 'pre-15:00' orders are supposed to be despatched the same day

Hopefully everything will be here by the beginning of the week
I'm days-off today/tomorrow, & will be going to work in the car on Sunday
Next week, I'm on 'early-turns', so Preston; my blue Ribble will be dragged out of the shed, & have the lights transferred onto it for a couple of days

 

[T4tomo]

glad you're Ok and the mech hanger did its job

 

[Cycleops]

While I was fiddling about with the rear mech on my new old mountain bike (Deore XT) I noticed the lower jockey wheel had cracked almost right across. Could this have happened here?

 

[fossyant]

Something similar happened to a forum member at Llandegla. Jockey came off, bang, bits of mech bouncing back down the trail.

 

[MichaelW2]

How convenient that the hospital provides Cinelli Wipes for passing cyclists.

I had a plastic Sram derailleur fracture and the chain wrapped tight around the axle. Not a chance of a roadside repair but I was close to home.

 

[I like Skol]

All I can assume is that, for some reason, the lower jockey-wheel bolt dropped out, & the chain 'swung' into the spokes, taking with it, the cage, which then moved over, as the chain tensioned??
The lower-bolt has a habit of working loose, but if it's fully tight, the jockey-wheel might as well be siezed

I know this won't make you feel any better but sounds like you have been caught by your own blase attitiude to repairs and maintenance. Running with that lower jockey bolt in the state you describe is a disaster waiting to happen.

On a positive note, at least you know why it happened so there is no doubt about the indexing or stop screws set-up being questionable and once you make good the repairs it should all be golden.

 

[Richard A Thackeray]

@I like Skol

The limit-screws were never an issue, as I can't remember being on a hill steep enough that I can't get up on the 4th (12-28/10-speed)
That bolt was part of a fortnightly check, & I stated, it was due for the check-over today or tomorrow

How convenient that the hospital provides Cinelli Wipes for passing cyclists

It is!!
Not just passing, but en-route there for a 'late-turn'

glad you're Ok and the mech hanger did its job

More to the point, barely any traffic on/leaving roundabout, or I'd have been very embarrassed being;
1. Scooped up, by a Paramedic crew, I probably knew
2. Dealt with by A&E Nurses/Doctors, that I would know (& received miniscule amounts of sympathy/'friendly abuse'
3. If any other vehicles had been involved, interviewed by a memvber of Roads Policing that I also know

 

[Ajax Bay]

for some reason, the lower jockey-wheel bolt dropped out, . . . The lower-bolt has a habit of working loose, but if it's fully tight, the jockey-wheel might as well be siezed

Skolly's not having a go at you for the limit screws.
Who seriously checks their jockey wheel bolts fortnightly?
After a very infrequent 'super' clean where the cage plate has been removed (and/or for replacing jockey wheels) the bolts go in with a dab of threadlocker on. No further maintenance required, blase or not.
That naughty little 'lower bolt' and its dangerous little 'habit'! Have a word with it.
The bolts must be "fully tight" otherwise they will work their way out, and the RD will fail. If you find that that stops the jockey wheel going round, there's an 'issue' - which needs sorting out (?very slightly longer bolt?). The solution is not to leave the bolt loose and check it every week/fortnight.
On the plus side, there may be some fell running or orienteering in the summer.

 

[Richard A Thackeray]

@Ajax Bay

I realise it's not a serious dig

The 'fortnightly' was a check of everything
Still, the new (old/slightly used) Ultegra mech appears to rotate freely, when as tight as it will go

 

[Blue Hills]

Never had this happen but have now and again wondered about jockey wheel bolts coming out - will check more often.
Fair to assume that they are designed so that it's impossible to overtighten them and restrict the movement of the jockey wheel?
Do folks add anything to help them stay put? Blue loctite?

 

[Ajax Bay]

ETA: Tightening them 'sensibly' will, by design, not reduce the width of the cage and not restrict the movement of the jockey wheel. Which is why the OP needs to find out why when "it's fully tight, the jockey-wheel might as well be siezed". The cage is designed to be a little narrower (with the bolt "fully tight") at the lower tension wheel than at the upper 'guide' wheel. The guide jockey wheel has about a mm of sideways float to help it align with the sprockets.
I add a dab of threadlocker (medium) on mine.
While I'm at it, here's my list:
RD pulley wheel bolts
Chainring bolts
ISO/post mount bolts
Mudguard stay and chainstay bridge bolts
BB
Stem bolts
cleat bolts

 

[Richard A Thackeray]

New sacrificial hanger has arrived this AM (ordered about 23:30, Thursday)

Never had this happen but have now and again wondered about jockey wheel bolts coming out - will check more often.
Fair to assume that they are designed so that it's impossible to overtighten them and restrict the movement of the jockey wheel?
Do folks add anything to help them stay put? Blue loctite?

Not over-tightened in my case, plus I use KMC chains, so they have the 'quick-link'

As An Aside;
It was a 105 mech, & the indexing had never been adjusted since the bike arrived (March 2017)
Well, until a cable snapped last month, inside the 'brifter'

 

[Smokin Joe]

Never had this happen but have now and again wondered about jockey wheel bolts coming out - will check more often.

Happened to me once on a Benelux mech.

 

[Richard A Thackeray]

Bought some Thread Lock on my way home from work yesterday
Hopefully the wheel should arrive today, and be waiting when l get home from work at 14:30
I took its predecessor out of the shed to use & put some lights on it
I’d almost forgotten how light, responsive, easy rolling it is

 

[IanSmithCSE]

Good morning,

Interesting that you mention 105, however there are a lot of 105 rear mechs out there so there are bound to be coincidences.

Quite a few years back I had a snapped chain, trashed rear mech, cassette and spoke damage and I had assumed that the chain splitting was the cause, but the rear mech damage was a bit odd.

It did seem a bit surprising to see the inside of the rear cage breaking where it had.

Although you can't really see it in the photo the outer side of the cage is unbent and the inside of lower wheel the is also not bent.

I had always assumed that the chain split and all other damage was a result of that, but if somehow the inside cage plate had failed then the chain would have come off with a similar result to that I experienced.

For a chain to be able to break the side plate in this way I would have expected more damage to the jockey/pulley wheels, far more than the quite light damage that can be seen in the photo.

Does your cage have any signs of failure, especially around where the lower bolt goes, hence the self undoing?

The rear mech was only in the low 1,000s of miles and the jockey/pulley wheels are in a lot better condition than the shadows in the photo suggest.

Looking at the other side of the mech there is a noticeable fracture.

I got side-tracked a while and back spent an afternoon reading various articles on how tight nuts become undone, it was started by the "quick release is unsafe with disc brakes" discussion.

Bye

Ian