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Warning about back derailleur screws

zefszefs Posts: 484
edited February 2018 in Workshop
I would advise to check the 2 little screws (in my case M4's) that keep the back derailleur in place with the frame hanger as I have already lost 1 of them and have noticed them getting loose over time. Some people recommend loctite since if these get loose/fall on a ride the derailleur can come off and cause an accident.

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  • StillGoingStillGoing Posts: 5,207
    Should have been loctited in from build.
    I ride a bike. Doesn't make me green or a tree hugger. I drive a car too.
  • MatthewfalleMatthewfalle Posts: 17,380
    Should really check them as part of your6 month bike check/wine drinking/Benson smoking plan as per previous posts.
    Postby team47b » Sun Jun 28, 2015 11:53 am

    De Sisti wrote:
    This is one of the silliest threads I've come across. :lol:

    Recognition at last Matthew, well done!, a justified honour :D
    smithy21 wrote:

    He's right you know.
  • cooldadcooldad Posts: 32,599
    Not sure what the random second picture is for.

    Simple rule when doing up anything with multiple bolts, from bike bits to car wheels, is do bolts up bit by bit before tightening fully
    I don't do smileys.

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  • Good call. Just checked the hanger on my Scott Solace and found the rear bolt to be slack...
  • lesfirthlesfirth Posts: 1,356
    If your QR skewer is correctly tightened your rear mech will not come off if these screws come loose and fall off.

    As others have said it is wise to keep a check on all bits of your bike.
  • zefszefs Posts: 484
    lesfirth wrote:
    If your QR skewer is correctly tightened your rear mech will not come off if these screws come loose and fall off.

    As others have said it is wise to keep a check on all bits of your bike.

    Yes, but if the bolt comes loose and you remove the wheel for maintenance it might come off, that seems like what happened in my case.
  • Fair point about checking the bolts but never had this happen in over 50000 miles of cycling on several different bikes. Maybe I've been lucky but reckon you must have been very unlucky.
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  • zefszefs Posts: 484
    noodleman wrote:
    Fair point about checking the bolts but never had this happen in over 50000 miles of cycling on several different bikes. Maybe I've been lucky but reckon you must have been very unlucky.

    After doing some research it seems more prone to happening on some brands and could also be a manufacturing issue or low quality parts. Not that uncommon though.
  • FishFishFishFish Posts: 2,152
    According to your research, which brands are more prone to this?
    ...take your pickelf on your holibobs.... :D

    jeez :roll:
  • MatthewfalleMatthewfalle Posts: 17,380
    zefs wrote:
    lesfirth wrote:
    If your QR skewer is correctly tightened your rear mech will not come off if these screws come loose and fall off.

    As others have said it is wise to keep a check on all bits of your bike.

    Yes, but if the bolt comes loose and you remove the wheel for maintenance it might come off, that seems like what happened in my case.


    perhaps if your maintenance schedule or skill set would have included checking the bolts occasionally they maý not have come loose.

    as an aside, what kind of accident as per your first post do you foresee when performing the maintence you describe?
    Postby team47b » Sun Jun 28, 2015 11:53 am

    De Sisti wrote:
    This is one of the silliest threads I've come across. :lol:

    Recognition at last Matthew, well done!, a justified honour :D
    smithy21 wrote:

    He's right you know.
  • MatthewfalleMatthewfalle Posts: 17,380
    zefs wrote:
    noodleman wrote:
    Fair point about checking the bolts but never had this happen in over 50000 miles of cycling on several different bikes. Maybe I've been lucky but reckon you must have been very unlucky.

    After doing some research it seems more prone to happening on some brands and could also be a manufacturing issue or low quality parts. Not that uncommon though.


    yes _ I too am very interested to know about your research, the brands that its happening on and whether its down to manufacturing defects, q/c issues, low quality screws or whatever.

    As its not that uncommon (as per your post) it should be an interesting read.

    Links to source documents are required, narurally.
    Postby team47b » Sun Jun 28, 2015 11:53 am

    De Sisti wrote:
    This is one of the silliest threads I've come across. :lol:

    Recognition at last Matthew, well done!, a justified honour :D
    smithy21 wrote:

    He's right you know.
  • StillGoingStillGoing Posts: 5,207
    I call bull.

    Screws securing things in should have thread lock. Screws securing things in should be checked as part and parcel of periodic maintenance. I too am intrigued as to what danger was posed when removing the rear wheel?
    I ride a bike. Doesn't make me green or a tree hugger. I drive a car too.
  • pilot_petepilot_pete Posts: 2,120
    Someone finds they have a screw loose and tries to make a story out of it... :roll:

    I’ve NEVER had a hanger screw come loose, but perhaps that’s because I’ve always installed them correctly with a bit of blue loctite...

    Mind you, have you never seen a rear derailleur come apart from its mount and swing down by its shifter cable? Bloody lethal! Be careful out there...

    PP
  • I swapped the hanger out on my winter bike (I didn’t use loctite so there’s one reason there wouldn’t be any!!!!) the two bolts sit underneath the qr spanner so even if they were Loose, they can’t fall out cos the spanner’s in the way. If I looks at my best bike, they go in from the other side but they won’t come out cos the cassettes in the way. My TT bike on the other hand are quite accessible and in theory could fall out but there are 2 and the chances of 2 working loose are so small it would only come down to human error. So if in doubt and your really paranoid about it, put some tape over them.
  • MatthewfalleMatthewfalle Posts: 17,380
    So if in doubt and your really paranoid about it, put some tape over them.


    Alternatively, you could always weld them in.
    Postby team47b » Sun Jun 28, 2015 11:53 am

    De Sisti wrote:
    This is one of the silliest threads I've come across. :lol:

    Recognition at last Matthew, well done!, a justified honour :D
    smithy21 wrote:

    He's right you know.
  • FishFishFishFish Posts: 2,152
    So if in doubt and your really paranoid about it, put some tape over them.


    Alternatively, you could always weld them in.


    Loser advice.

    I always keep identical bikes in parallell universes when cycling so that when the much researched screw event takes place then I'm on it. In a manner of speaking.
    ...take your pickelf on your holibobs.... :D

    jeez :roll:
  • zefszefs Posts: 484
    The point of the post was to inform people who weren't aware of these bolts to have them under their maintenance check. I wasn't aware of them and found out one was missing by luck, so now that I know these can come loose I made a topic about it, not sure why this would get some annoyed, haha. Why would anyone know that they need to use blue loctite to secure these bolts? that should be the manufacturers problem. You can search on the web to see which brands have been reported for that issue, although as I said it could be related to quality control. You want me to name the brands so that you get all defensive about your bike? give me a break...
    Maybe get off your high horses when someone is trying to be helpful on this forum.
  • StillGoingStillGoing Posts: 5,207
    zefs wrote:
    The point of the post was to inform people who weren't aware of these bolts to have them under their maintenance check. I wasn't aware of them and found out one was missing by luck, so now that I know these can come loose I made a topic about it, not sure why this would get some annoyed, haha. Why would anyone know that they need to use blue loctite to secure these bolts? that should be the manufacturers problem. You can search on the web to see which brands have been reported for that issue, although as I said it could be related to quality control. You want me to name the brands so that you get all defensive about your bike? give me a break...
    Maybe get off your high horses when someone is trying to be helpful on this forum.

    People change their hangers when they are no longer straight so it isn't something that is just done at manufacture.

    You said you've done the research, so please reveal who these dastardly manufacturers are that are endangering us when we remove the rear wheel and what danger will befall us all?
    I ride a bike. Doesn't make me green or a tree hugger. I drive a car too.
  • zefszefs Posts: 484
    If the derailleur coming off mid ride is not an issue maybe we should be cycling with loose quick releases as well.Yes the screws stay in place by the quick release nut but as I said the loose screws can come off when you remove the wheel to do maintenance and you may not notice that when going for a ride, that's all.
  • MatthewfalleMatthewfalle Posts: 17,380
    zefs wrote:
    The point of the post was to inform people who weren't aware of these bolts to have them under their maintenance check. I wasn't aware of them and found out one was missing by luck, so now that I know these can come loose I made a topic about it, not sure why this would get some annoyed, haha. Why would anyone know that they need to use blue loctite to secure these bolts? that should be the manufacturers problem. You can search on the web to see which brands have been reported for that issue, although as I said it could be related to quality control. You want me to name the brands so that you get all defensive about your bike? give me a break...
    Maybe get off your high horses when someone is trying to be helpful on this forum.


    I have several bikes from different manufacturers, including, unfortunately, a Trek.

    I am very intrigued to see your source material and your findings on which manufacturers have this issue.

    Perhaps you could do a quick spreadsheet?
    Postby team47b » Sun Jun 28, 2015 11:53 am

    De Sisti wrote:
    This is one of the silliest threads I've come across. :lol:

    Recognition at last Matthew, well done!, a justified honour :D
    smithy21 wrote:

    He's right you know.
  • MatthewfalleMatthewfalle Posts: 17,380
    zefs wrote:
    If the derailleur coming off mid ride is not an issue maybe we should be cycling with loose quick releases as well.Yes the screws stay in place by the quick release nut but as I said the loose screws can come off when you remove the wheel to do maintenance and you may not notice that when going for a ride, that's all.

    Why would you want to cycle with a loose quick release?

    The purpose, function and actions are utterly and completely different to that of the small screws.

    I am still intrigued by the correlation of taking the wheel out for maintenance purposes and the mech falling off as you speed along.

    Perhaps you could add this to the spreadsheet with the findings of your research.
    Postby team47b » Sun Jun 28, 2015 11:53 am

    De Sisti wrote:
    This is one of the silliest threads I've come across. :lol:

    Recognition at last Matthew, well done!, a justified honour :D
    smithy21 wrote:

    He's right you know.
  • zefs wrote:
    noodleman wrote:
    Fair point about checking the bolts but never had this happen in over 50000 miles of cycling on several different bikes. Maybe I've been lucky but reckon you must have been very unlucky.

    After doing some research it seems more prone to happening on some brands and could also be a manufacturing issue or low quality parts. Not that uncommon though.

    Can't agree with that. Don't know anyone this has ever happened to and this is in nearly 30 years of mtb and road riding. This includes fellow club riders who also have 2 or 3 bikes each. User error maybe but it's about the least likely part on the entire bike to come loose.
    argon 18 e116 2013 Vision Metron 80
    Bianchi Oltre XR Sram Red E-tap, Fulcrum racing speed xlr
    De Rosa SK pininfarina disc
    S Works Tarmac e-tap 2017
    Rose pro sl disc
  • cooldadcooldad Posts: 32,599
    As everyone else seems to be pedantically and annoyingly picky, those screws are not derailleur screws, they are bolts for the hanger.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • zefszefs Posts: 484
    noodleman wrote:
    zefs wrote:
    noodleman wrote:
    Fair point about checking the bolts but never had this happen in over 50000 miles of cycling on several different bikes. Maybe I've been lucky but reckon you must have been very unlucky.

    After doing some research it seems more prone to happening on some brands and could also be a manufacturing issue or low quality parts. Not that uncommon though.

    Can't agree with that. Don't know anyone this has ever happened to and this is in nearly 30 years of mtb and road riding. This includes fellow club riders who also have 2 or 3 bikes each. User error maybe but it's about the least likely part on the entire bike to come loose.

    You can search on google to see if it happens or not, both on mtb and road bikes.
    https://www.google.gr/search?q=deraille ... ygXQ_a2QAw

    On another forum people were reporting that it was causing creaking on their bikes as well (Giant Defy) and it was the screws causing the issue.
  • That link you posted is describing the deraileur being loose on the hanger. What you've been referring to is the hanger bolts coming loose.
    argon 18 e116 2013 Vision Metron 80
    Bianchi Oltre XR Sram Red E-tap, Fulcrum racing speed xlr
    De Rosa SK pininfarina disc
    S Works Tarmac e-tap 2017
    Rose pro sl disc
  • zefszefs Posts: 484
    noodleman wrote:
    That link you posted is describing the deraileur being loose on the hanger. What you've been referring to is the hanger bolts coming loose.

    Not sure if you are referring to the first result of the google search but there are more results. If the bolts are loose the hanger and the derailleur move as well.
  • zefs wrote:
    noodleman wrote:
    That link you posted is describing the deraileur being loose on the hanger. What you've been referring to is the hanger bolts coming loose.

    Not sure if you are referring to the first result of the google search but there are more results. If the bolts are loose the hanger and the derailleur move as well.

    But as pointed out, for the majority of bikes, the QR spanner will hold everything in place even if they both fell out since the small piece of metal that is the hanger and the frame are clamped inside the whole mechanism that holds the wheel on the dropouts. The chances of a catastrophic incident occurring due to a screw working loose are so small you have more likely things to worry about like a tyre exploding or a spoke snapping or a duck being struck by lighting right above you and it falling on your head Causing you to swerve into the path of a school bus full of nuns
  • pilot_petepilot_pete Posts: 2,120
    Zefs

    People are taking the p1ss because you tried to make a mountain out of a mole hill. You cliam that hanger screws can come loose and cause real danger to the user. This is simply a rather naive assumption from someone who obviously has little mechanical understanding.

    You say ‘how am I supposed to know that blue loctite is required?’ The answer is you are not supposed to know anything about how a bicycle is manufactured or put together, you are simply an end user who needs to know how to operate it. You don’t know anything until you know it, so if you want to do cycle maintenance take the time to learn. They are very simple mechanical contraptions and it really isn’t difficult with the right tools and a willingness to learn.

    Bicycles are subject to significant vibrations in use and as such many bolts could work loose. Virtually all the threads require either threadlock (blue loctite as you will be able to get it undone again as opposed to red which is too strong for bike bolts), or anti-seize (such as coppaslip) to prevent threads corroding together. Remember most bolts are subject to harsh conditions such as road spray, water and or sweat and many are steel/ stainless/ titanium threading into aluminium. Rarely is putting a bolt in completely dry the best option.

    So, that answers how the hanger bolts should be installed and now you have learnt something. Now have a think about your claim that one of these screws coming loose could pose a real danger. That is a ridiculous claim. As has been pointed out the quick release normally clamps the hanger in position when installed correctly so the hanger can’t just fall off even if one(or both) of the screws comes loose. When challenged on this you then tried to say that if you took the wheel out and then put it back there could then be a danger. Again mate, just sounds like a wild claim which you cannot back up with a reasoned example of what this danger could be.

    Let’s just humour your idea though. Whilst riding let’s assume that the hanger comes off. What exactly is the danger? The rear mech falls off complete with hanger. You keep pedalling until you feel a lack of resistance (about half a pedal stroke) and hear something that sounds mechanically bad. What’s the worst thing that can happen? Mech ruined, maybe a couple of spokes damaged, stays chipped/ scratched or cracked? Bloody annoying and possibly expensive, but I still can’t quite see the danger aspect.

    Let’s get onto your research. You won’t get a doctorate by searching google (unless you search for one and buy it from Africa). To make out that you have done research and this is a big issue for many manufacturers yet choose not to provide this research when challenged demonstrates yet again that you are trying to sound like you are raising a serious safety issue when in fact all you are doing is inflating a simple problem into something it is not. The crux of it is that bolts can come loose on bicycles unless installed correctly (which is hardly revelatory). If you are naive enough to buy a bike and never carry out any preventative maintenance/ safety checks then one day you may find a loose bolt... no need to hold the front page though when it happens. :roll:

    PP
  • zefszefs Posts: 484
    You still don't get the point and maybe it was my fault not describing it correctly. If the bolts are loose without you knowing about it, next time you remove the wheel they can both come off (for me only one did) and then when you go for a ride without noticing (although the derailleur would come off), it could cause an issue. That's why I mentioned they should be checked if someone is not aware of this, pretty simple.

    So since on my bike I noticed them becoming loose twice within a few months, and it may happen on other bikes as well the loctite solution was suggested.

    Even if one comes off it could potentially damage the hanger or even the frame (I don't know) since the hanger is moving/flexing with 1 bolt only.

    If using the word research instead of search was wrong then blame my english degree, haha (although I am sure you know I meant google search).
  • pilot_petepilot_pete Posts: 2,120
    Stop press - bolts can come loose on bikes.

    I think that’s it in a nutshell. I’d stick to English. :wink:

    PP
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