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Interested in the thought of the single track collective.
purchased a new bike for my son, Nukeproof Mega from a physical shop, not online last month, the bike was PDI’d prior to sending to us, so just had to fit bars and wheel. After the first ride out, I noticed the rear brake callipers bolts were no more than finger tight so I quickly went round the bike and torqued (almost) everything properly. This included tightening the bar stem, brake levers, shifter. A few weeks on, I noticed a slight rattle so checked the pivots and shock bolts, all loose, I’ll pick up some loctite blue and refit these properly. One thing I didn’t check was the derailleur bolt.. queue call from son half way up a hill, the bolt had come loose, chain ended up in spokes, chain snapped and derailleur bent. All on a one month old bike that has seen use but nothing extreme like laps of FW. I’ve contacted the bike shop and whilst they haven’t responded directly to me, they did put a post on their socials referring to the importance of checking and torquing before each ride. Good advice, however I’ve never seen a derailleur just fall off, so unfortunately missed this from my inspection. Am I at fault, or poor PDI, bearing in mind nothing was correctly torqued when I got the bike? Thoughts?
In an ideal world any bike from an LBS 'should' be good to go out the door*.
It's not something I've ever had a problem with, but friends have had similar issues to you.
The disclaimer many give often feels like tacit acknowledgment their spanner monkeys aren't that good, after all, it's a mountain bike not rocket science.
*Props to Andy at Setchfield cycles for top class service and always making sure my bike is good to go.
The shop should have double-checked everything.
I always check everything myself when I buy a new bike.
Once you noticed the caliper bolts were loose, checking everything would have been sensible.
It’s been ridden a few times, therefore your fault I’m afraid. Derailleurs come loose even when correctly torqued.
Every bike ive bought online jas had issues. My sons PDI'd Frog was essentially a box if bits!
Thenonly well assembled online bike was from PlanetX!!!
Derailleurs come loose even when correctly torqued.
Do they, this has never happened to me in 35+ years of riding.
I bought a Nukeproof Scout last year. Checked most of the bolts as you do. A few rides in on a big all-day ride whilst on holiday in Wales, the left crank fell off!
Managed to bash it back on with a peice of wood but the plastic preload nut was stripped. Luckily seem to have got away with it, holiday saved and no lasting damage it seems.
I always check everything and don't let shops touch my bike, Even my new Shand was partially stripped and rebuilt once I got it home.
Yes its clearly been badly set up in your case. Derailleurs properly set up just do not come loose by themselves. However proving it will be almost impossible and any claim would be for "consequential damage" which is also very hard to prove ie the fault is the deraillier came loose. The consequential damge is to the wheel.
Personally I would make contact with the shop. Politely tell them they effed up and ask them to sort it. But do not invest too much time and energy on it as your case is weak in that its very hard to prove.
Free parts is probably the best you can hope for
Must have shifted like an absolute dog if the mech was that close to coming off.
It's not a good look for the shop, I think balance of probabilities says that it wasn't done up properly in the first place given that all the other bolts were wrong. But proving it after a month, not likely, and putting that message up on their socials gives you a clue as to what their response will be when they get back to you.
That is shit and really unsafe, especially the brakes. I’ve only ever bought a couple of new bikes in my time, and they arrived in boxes and apart from turning the bars etc were good to go.
Do they, this has never happened to me in 35+ years of riding.
Yes. Just about every bolt can rattle loose in my experience, up (down?) to and including grub screws!
Never trust a PDI, I always undo pivot bolts on a new frame/bike apply threadlock and torque to spec, little stickers or a silver Sharpie line on the pivot bolt heads is a good idea to check for any undoing at a glance, never had a rear mech come loose or caliper bolts, I'll blame both on the bike shop, they've clearly not been checked and torqued correctly, pivot bolts are a known Nukeproof issue, I've read bike tests where they've mentioned them coming loose, they should be threadlocked and torqued correctly, there's no excuse for it.
Maybe I'm the idiot but I don't trust bikes built by bike shops. Maybe I would if they provided a completed and signed quality sheet with the bike. I go over all bikes and check the bolts are tight when new.
Strange that I trust a car garage though 🤷♂️
Derailleurs do come loose by themselves. It’s happened to me on a couple of occasions, and it’s also happened to a few people I know.
I’ve also had calliper bolts come loose too. And that was my fault for not checking them often enough.
They only will come loose if not done up properly. Never had one come loose in 50 years of riding. Ther should be no loading on them to make them come loose. If it comes loose something is wrtiong
It's a difficult one, the shop probably did a poor job but on the other hand, bolts do come loose and require occasional checking. One of my suspension pivot bolts was loose a few weeks back, I check them occasionally and in a few years of ownership it's never come loose prior to that so you can't assume that it's not going to happen.
Do they, this has never happened to me in 35+ years of riding.
I’ve never had one come loose but just been on holiday, wife on a hired bike and one day complained of bad shifting. We assumed she must’ve smacked the mech on something but on checking it was loose and needed tightening. That evening one of the other guys was complaining about his shifting and again his mech needed doing back up, his was a newly rebuilt warranty replacement frame (built by a shop).
Personally I would make contact with the shop. Politely tell them they effed up and ask them to sort it. But do not invest too much time and energy on it as your case is weak in that its very hard to prove.
I’d do this too. Sometimes I think I give up too soon though and should probably fight for longer, but life’s too short.
Trust me. They can be done up properly, with a torque wrench, and they can come loose. I know, because it's happened to me, both the doing up, and the coming loose. Not often, but on more than one occasion, when riding in the Alps. Same to my buddy.
What's amazing is how loose they can be, and still keep shifting reasonably well. Both with XO Eagle.
It may not have happened to you personally, but that doesn't mean it can't happen. I've never slept with a supermodel...
At the risk of turning the thread into "do derailleurs come loose on their own or not", I've had only one come loose, but I suspect that was because I had reassembled my bike after a flight and not applied any threadlock / tightened enough.
But yeah, if other bolts were loose on delivery, I'd take it as a learning experience and move on. I.e. shop elsewhere in future. Maybe I'm lucky but my LBS would be highly embarrassed to let a bike go out the door like that.
Maybe ask the bike shop if they will sell you a replacement derailleur at trade price?
It isn't acceptable that a brand new bike should need to be checked but sadly it does seem to be necessary. Infact I don't think I've ever had a bike that's good to go from the shop. I bought a hardtail in June and it came with non-indexed gears, rubbing brakes and air in the rear brake line. As a positive all the bolts where correctly torqued and greased/loctite-ed
Trust me. They can be done up properly, with a torque wrench, and they can come loose.
Trust me - they will not if done up properly with correctly prepared threads. If they come loose something has been done wrong. My guess would be over reliance on a torque wrench that has not been calibrated or worn, damaged or dirty threads. Bolts correctly specced and fastened properly simply do not come undone
Agree that it should be checked, and it probably wasn't in this case. However unless it was a problem on the very first ride, the shop can say that it was the rider's responsibility.
Also, I suspect that the job of checking new bikes will be done by the Saturday kid, because it's one of the most boring jobs in the shop.
Riding 40 years never had a mech come loose on my own bikes or customer bikes... May be a new thing I don't know....
The shop should have double-checked everything.
I'd say that this is implicit in the extra cost you'll pay buying from an LBS.
Derailleurs come loose even when correctly torqued
Just to add to the disagreement, I've had it happen once, quite recently. My shifting suddenly went all to pot; on inspection the rear mech flopping around and probably a few threads away from dropping off. To be fair I fitted years ago and have probably never touched since; I'm not great at rechecking bolts (probably need to start threadlocking stuff).
I have a buddy who suffers bolts coming loose at inopportune moments.
His torque wrench is some off brand Xmas cracker unit that is left wound up etc. He knows better but forgets.
I suspect(know) the two are related.
I never use a torque wrench on my bicycle. I have one but its not accurate at the low torque that is used on the small bolts on bicycles. Over the years you develop the feel for correctly tightened bolts. I never have bolts coming loose but I am meticulous in my prep. I never use locktite either.
Correctly torqued things can often loosen off, and there are a few reasons for it.
It's why a quick M-check should be done before riding a bike, then every few rides give everything a quick check with a set of allen keys (the three pointed wrenches are ideal for this, as it saves swapping tools).
However with a new bike, I'd always go over it with a set of allen keys after the first ride, or after anything has been swapped, as that's when things are most likely to settle in/loosen off.
Aside from bolts coming loose that shouldn't, I think the OP has missed the opportunity to complain with an expectation of getting anything from the shop.
The bike should have been rejected or at the very least the shop made aware of a lot of loose bolts as early as possible and given the chance to rectify it - before taking to bolts yourself and deffo before riding it.
Agreed it is a huge pain in the arse when you just want to ride a new bike and it is easy to tighten bolts yourself but, once it is out of the shop and an owner starts making remedial work themselves and goes for a few rides before anything happens - I'd expect any shop would shrug their shoulders responsibility wise.
They may look at it from a good will perspective but doubt any would admit liability in this case.
I always give any new bike a thorough check before the first ride, partly as a check but also to set up the bars, stem, shifters etc to my preference. Every bike I've had in the last 15 years or so has needed something tightening or realigned, apart from one. So props to Cotic for not only having great packaging but the gears were 100% correct (including limit screws), the bars were at a decent angle, the saddle was level and the brakes were aligned perfectly. Took me a while to accept there wasn't anything I'd missed before the first ride! Every bike has had something come loose over the first ride to two though as things bed in, it's why I do a full bolt check after every ride anyway (yes I've had a rear mech work loose on occasion).
I'd ty it with the shop but after a month it's going to be tough. Seeing as so much was loose when you received the bike I'd have given them a call then, only if it meant they just checked other bikes before being sent to other customers.
Bike shop's fault. Absolutely shouldn't happen. However, your chances of getting that to stick are IMHO quite unlikely. When you found loose bolts you should have got it back to the shop, or at the least highlighted the issue then. Having then taken on the maintenance yourself has sadly given them the get out.
Mine came loose at bpw this week. Only about an eighth to quarter of a turn, enough that the mech wobbled slightly. Only noticed when cleaning, shifting was still perfect.
Assembled by me, two weeks ago, as I came back from abroad and had removed for the flight.
the mech bolt is probably unique in that it will see high frequency oscillating rotation loads from the mech bouncing around, which could work a bolt loose.
Trust me – they will not if done up properly with correctly prepared threads. If they come loose something has been done wrong. My guess would be over reliance on a torque wrench that has not been calibrated or worn, damaged or dirty threads. Bolts correctly specced and fastened properly simply do not come undone
Just because you've not experienced it, doesn't mean it can't happen.
As testified by plenty of others on this thread.
Every time I've bought a bike from a shop, they have offered a free inspection/service after 2-4 weeks since things do sometimes come loose. Never taken this up though since I routinely check myself.
Kramer - and others agree with me. Properly specced. prepped and tightened bolts just do not come loose. Otherwise the world would fall apart. the only reason they come loose is if something is wrong.
If you say something never happens, it only takes one counter example to prove you wrong.
I never use a torque wrench on my bicycle. I have one but its not accurate at the low torque that is used on the small bolts on bicycles. Over the years you develop the feel for correctly tightened bolts. I never have bolts coming loose but I am meticulous in my prep. I never use locktite either.
Really?
Loads of testing shows that pro-mechanics frequently over-torque bolts (not least due to to common practice of 'going round every bolt and giving it a tweak')
I've got (a couple of) decent quality torque wrenches (to cover high and low range) that gets used for critical stuff and despite having built my own bikes for many years I'd say I would still have a high risk of undertorquing the 'bastard tight' stuff and overtorquing the small stuff. Sure the average m4/m5/m6 bolt will be close to the right range (checked a shimano crank bolt the other day as I'd worked out how to get my torque wrench into the restricted space and it was very slightly under the 14nM spec)
But I've had loads of stuff come loose over the years - usually when exposed to an unusual load or sustained hard riding (bottle cage bolts had been fine for many years before the cobbles of the Tour of Flanders, brake caliper on hard rutted Isle of Wight bridleway) but I've had mechs come loose*, properly torqued rear axles need checking frequently IME,
*I try to make it the first thing I check if shifting goes out but frequently end up messing with cable adjuster first....
Haven't bought a complete new bike since the 90s.
If anything were to drop off any of my bikes ,I know the idiot to blame 😆 🤣
At the kids bike club ,as part of their pre-ride check,we teach them to always do a bounce test and listen for any rattles,then all the main points,brakes,steerer,etc,etc.
It only takes a few minutes.
They also get told to look for any faults when they are washing the bikes (yes they wash the club bikes 'occasionally') 😆 🤣
Depends on the rear mech. If it had a normal pivot concentric with the hanger bolt, then very unlikely to come undone.
But some of the Shimano ones like attached image have a separate pivot further back, and the bit bolted to the dropout is clamped solid, so it can act like a spanner and work the bolt loose. This is especially true if incorrectly fitted in the first place with the tab not sitting hard up to the b-tension notch on the dropout.
https://www.merlincycles.com/shimano-xt-m781-10-speed-rear-derailleur-58066.html
During COVID I was coerced into helping the lbs build bikes up in the evenings. He was adamant everything on the lower end stuff had to be done up crazy tight due to the habits of the end users..... And still people came back having somehow managed to twist the front mechs by neanderthal shifting.
Most specified bike torques are to stop people squashing or stripping things. Very few (mostly crank related) are actually to do with achieving optimum bolt tension and clamping loads.
https://www.boltscience.com/pages/info.htm?
Kramer - my point is they do not come undone without something being wrong. They never "just come undone" there is always a fault that makes them come undone
In the case or rear mechs many of them swing on the fixing bolt. If that bolt is partially seized it could put enough force into the bolt to make it come undone. Thats not the bolt "just coming undone" thats the bolt coming undone for a reason. Other reasons? Damaged threads, dirty threads meaning the torque at the torque wrench is less than required to tighten it properly so despite the torque wrench the bolt is actually too loose or the thred is damaged to the point there is enough space between the two parts for it to become undone etc etc
B33k34
You note on this thread its those who use torque wrenches have bolts coming loose. 🙂
any claim would be for “consequential damage” which is also very hard to prove
No, that's not correct. Damage to the wheel caused by a loose derailleur would still be direct loss. Consequential loss would be the derailleur failing which meant I was late for my appointment with Alan Sugar and he didn't buy my company for a million pounds.
Ok, so we're agreed that they can come undone then, and do, for various reasons.
Therefore, in the context of this thread and the OP's question, very hard to prove that if the reason that the mech went into the spokes (again, a reasonably common occurrence in mountain biking, usually because the derailleur has hit something and bent the mech hanger) was purely because the bolt had loosened, it was definitely down to the bike shop not assembling it properly.
Yup - I agree with that assessment. Occams razer would say that the fault lies with the shop and I am sure that is so but proving it? Impossible
Thinking about it, the times that I've found it loose on the bolt it is highly likely that is is because I've hit my derailleur on something. That's definitely happening more often now that I'm on a bigger, faster bike.
Same with my mate to be honest, he tends to smash through things.
It's a reason that I'll upgrade to Transmission for my next drive train.
You note on this thread its those who use torque wrenches have bolts coming loose.
I'm thankful for having a mate who's an aircraft engineer. He checks my torque wrenches on his fancy calibration device in his work hanger.
Brand new X-tools one a few years ago was way off out the box. Thus far my Halfords ones have served me well.
Not quite bits falling off but recently bought an ebike with gx axs gears, of 12 only about 5 were indexed properly, the rest were all over the place. I was going to take it back but thought it was something that would be handy to know so watched a few vids on YouTube and got it sorted myself, then refused the offer of a free six week check up by the shop where I bought it
I'd expect everything to be built correctly. I wouldn't trust everything to be built correctly. I've had this happen to friends numerous times (and me). Things do come loose but some shops just aren't very good at what they do. Not everyone gets a bike back from a shop and checks it over, why would they, they've just paid someone to sort it?
If you say something never happens, it only takes one counter example to prove you wrong.
What he actually said was:-
Properly specced. prepped and tightened bolts just do not come loose.
Which is absolutely true, as long as you expand it to include the things being bolted together.
The number of people on here (and everywhere TBH) who will swear blind that they "did it up properly" despite the thing falling off after three rides is indicative of the number of people who have no idea what "done up properly" actually is. And that includes a lot of shops, and scarily enough, a handful of manufacturers.
Only time i have things fall off my bike is when i've rushed and not done it properly. Or had a shop work on something.
The mechs on my DH bikes come loose frequently. I can tell as the shifting goes to garbage when the bolt is loose.
Torqued and locktighted.
They do come loose if ride hard.
Just remembered - the tiny bolts that hold the dropouts to the frame on my Shand did come loose. However I had not checked them and have since removed them, cleaned them and loctited them. Not come loose again. I assume undertightened when the bike was built up and there was no loctite on them
How are you buying from a physical shop if they are sending the bike to you? That's still mail order from somewhere you can't visit easily.
If I buy from an online shop I always PDI it myself. From a physical LBS probably wouldn't but then Id only use the LBS after building a relationship with them and trusting their work. Any shop worth it's salt would give the bike a check over a few rides after purchase just to check for things like this.
Buying online because it's cheaper means you need to take some responsibility for the checking of the bike imo. The reason it's more expensive from a walk in shop covers this valuable service.
Am I at fault, or poor PDI, bearing in mind nothing was correctly torqued when I got the bike? Thoughts?
And
Once you noticed the caliper bolts were loose, checking everything would have been sensible.
Is, I think, the start and finish of this particular tale of woe. Hope it's not trashed and you get the mech working again.
I never use locktite either.
The service instructions on my Bike Yoke dropper require it's use.
I never use locktite either
Erm, dropout bolts?
I just every so often do a quick is it tight check. Same as a garage telling you to check car wheel nuts after 30miles or so. In fact I've had a quick check and continental suggest this after a tyre change.
And both Shimano and SRAM rotor bolts are pre-loctited
i’d be inclined to say that the bike wasn’t PDI’d. a month seems like an unreasonably short time for a correctly fitted mech to work itself loose.
all you can do is raise it with the shop. do you still have the paperwork that confirms that a PDI was undertaken?
nickc - hence my correction 🙂 I don't buy either shimano or sram rotors and use copaslip on the bolts when reusing old ones
OP, you did say something like "I've never seen a mech come loose" but in fairness that's not how a nut and bolt check should work, it should be "is this a nut or a bolt? Yes? Then I will check it". If you're only checking faults you've seen before you're always going to be leaving yourself wide open.
It does sound like it might not have been done well by the factory/shop though.
of 12 only about 5 were indexed properly, the rest were all over the place
On my GX AXS when you micro adjust one gear it’s the same adjustment for all of them. It just shifts the derailleur by 0.5mm each time electronically. It doesn’t do a different adjustment for each gear. You basically, put it in the noisiest gear and dial out the noise.
I never use locktite either.
However I had not checked them and have since removed them, cleaned them and loctited them. Not come loose again. I assume undertightened when the bike was built up and there was no loctite on them
The case for the prosecution rests, Your Honour
Hence my correction
When the mech hanger has one of those tiny bolts to the side, they can often come loose and need the blue.
After 2 years with a Marin SQ3 I am on mech hanger number 3. I eventually started taking a spare out on rides just in case. If it comes loose, the rear mech B screw grinds a hole through the hanger.
Really bad design. Got a couple of frames here with the SRAM UDH hanger, they're nice and sturdy, functional design, so likely won't have the same issue.
Mail order bikes need to be checked as if they’ve not been PDI’d, then take it to your LBS for a check over after a couple of months or less if it’s been used a lot.
One of my mates had the rear brake caliper fall off (and obvs lose the 2 bolts) part way down the 1st decent on the 1st ride of his new shiny SC Bronson. Forced him to check the front before going steadily back to the car ... front was loose too. Unbelievable from a bricks and mortar shop.
I ALWAYS check everything myself. As per another poster - even the Shand when it arrived (no problems there !!)
Hence my correction
I don’t understand why you have loctite if you never use loctite except when you use it?
sometimes I wonder if you argue the point for the sake of being contrary.
And yes I’ve had a rear mech come loose a few times. Probably because I didn’t tighten it enough. I use loctite sometimes, depends if I can be bothered to find it in my mess. But I only work on my bikes.
Sometimes?
I was feeling charitable 🤣
Must have shifted like an absolute dog if the mech was that close to coming off
^^That was my first thought, if it was a day or two after you took it home maybe, but a month after?
I do think there's a need for users to develop a bit more mechanical sympathy and sensitivity to when something doesn't feel/sound/work right and just stop and check.
I've been out riding with mates who were oblivious to loose cranks, headsets and even wheels!
TBH such people are potential show stoppers for themselves and anyone they ride with and I'm not keen to go riding with someone so unprepared.
After a month of use I'd say all bets are off on bolts remaining done up, and if you only tighten odd things when you happen to notice they're loose then you will miss something else, spot one thing do the lot.
There's a lesson for Junior in all of this and it's not about LBS liability.
If the bike is important to him and he doesn't want his rides and finances ruined by catastrophic sudden disassembly then he needs to get in the habit of checking all of the fixings on his bike for himself on a regular basis.
Modern mechs still shift surprisingly well even if they're half hanging off.
So, reply from the bike shop pretty much as expected.
- all nuts and bolts must be checked prior to each and every ride,
- and if you did not do that, its your fault.
- it's a cheapo mech on the bike (Deore) so you should have expected it to rattle itself off
- and this is the funny one which is utter rubbish- "you will also find pre-set torque settings are for an ideal environment at ideal conditions. Generally in real world testing the rider will adjust correctly if components are coming loose"
So, in short, a PDI is a waste of everybody's time if the onus is on the buyer to check everything. Just imagine if you had to quickly nip round every nut and bolt on your car after you drove over a cobbled road to prevent the car from falling apart!
Teaching mechanical sympathy to a 14 year old is a great idea, however not fair to place the burden on somebody of that age - I'll put myself in the camp of checking our fleet of bikes prior to most outings, especially safety critical items, but when Jnr nips out for a quick lap of the local woods with a pal, that's not always going to happen. And, no I didn't check the mech as I've never had one come loose, shall add that to the list though.
My advice to me is to buy from an online retailer, where my guard is up more and not go to an LBS, who in this case shipped the bike to me post PDI, to save a trip during a busy work week. Fortunately no significant harm done, and I used the opportunity to teach Jnr how to split and replace a chain, how to setup a new mech, how to use a torque wrench and where to apply loctite blue (and not to ever the loctite 638 I have on the shelf).
in their defence (just a little bit) when our Trek Session arrives tomorrow even though they've been brilliant on discussions, emails, etc, i will still check each and every bolt before i send the lad out on it.
Jeepers guys. I bought the loctite for that job. Its not that difficult to imagine
At that i would name and shame the shop. We all know their pdi was crap and that response is crap.
Yes they have no legal obligation but something like a free or at cost mech and free labour on a wheelbuild would have been a nice goodwill gesture at very little cost to them
Instead of gaining a loyal customer they lose one
Despite agreeing that it is probably advisable to check a bike over before using unless it comes from someone you trust, that would be one LBS I wouldn’t be using again. At the very least I would expect a goodwill gesture, perhaps a new mech and chain at cost price or a low value voucher - 20 quid or something. It’s a competitive world out there and it ain’t the pandemic anymore - customers no longer grow on trees….
Edit - lol snap Tj
So, in short, a PDI is a waste of everybody’s time if the onus is on the buyer to check everything.
I've never not gone over a bike with a torque wrench at least every couple of months and I do a version of the M check before every ride, and TBH (although its an extreme example) I've held a 40mm stem that was twisted by a pro DH rider . So I'm willing to bet that their torque settings for things like levers and stem bolts are probs a wee bit more than mine need to be.
I had a problem with the shock on my new bike in the shop (a very respectable chain), asked in the shop, was told "They're all like that mate" and believed them.
Turned out that there was a problem, also with the fork. But by the time I confirmed it, I'd already ridden the bike for almost a year, and so (shrug) there's not a lot I can do about it.
But it grates.
Ive never trusted bike shops when it comes to new bikes, I will always check them over when I get home.
Unfortunately I think OP should have told LBS that the bike was a mess when they first got it, or checked every single bolt on the whole bike.
At least he knows now not to trust the LBS again.
Ive never used a torque wrench or had anything come loose or stripped / damaged a part. Come close to it on a USE seat post, but thats their crap design rather than my skilz.