Gandeloft

Hello,

I've cleaned my brand new 2021 Cube Attention_SL's chain after having done some 250km on it. I'd turned the bicycle upside down for the procedure and used WD-40. WD-40 dripped all over the place and by the time I'd realized it it already somehow got into my rear brake pads so now the rear brake squeals and breaks less efficiently. All that is an interlude to the main problem; The Shimano XT deraillour stopped shifting properly as of then. I've tried retightening the cable and setting up the limit screws, but how could those have even been affected by anything I did? Bottom line is that the deraillour does not reach the lowest gear (largest cog) anymore and I can't figure out why. What could have changed by having turned my bicycle upside down and cleaned its chain, messily, with WD-40?

Just to add, I'd wiped the chain after cleaning it immediately, and have then let the bicycle sit for the whole night (not upside down) before lubing it and riding it. The WD-40 dripped onto the bike seat mounting point of the frame, so I'd taken the seat post off, wiped off the WD-40 and re-greased the seat post mounting point. That's just for some extra context since I have no idea what happened and any info has the potential to be of use.

Phil_gretz

Begin at the beginning.

Loosen the rear derailleur cable fixing bolt. Remove the chain. Remove the rear derailleur. Then, take the bike to your local shop and pay them to check/correct the derailleur hanger alignment.

Examine the rear derailleur. Is there anything obviously out of alignment, like a bent derailleur cage (pulleys out of plane with one another)? Re-install the rear derailleur.

With the cable still un-attached, manually swing the derailleur through its inward sweep. Does the upper (guide) pulley center align with the plane of the largest cog? If not, adjust 'L' limit screw and do it again. Remember that the guide pulley has self-aligning play built into its position on its mounting bolt. Centered is what you want.

With the cable still un-attached, examine the alignment of the guide pulley with the smallest, outer cassette cog. Similarly, if necessary, adjust the 'H' limit screw.

Re-attach the chain. Tighten the cable adjustment of the rear derailleur to its (inward) most slack position. Re-install the rear cable, maintaining enough tension on the cable while tightening the fixing bolt to (a) take up available cable slack, but (b) not deflect the derailleur inward on its travel.

With the bike suspended (not upside down on the ground), turn the cranks and sweep through the shifting. Is the smallest gear in alignment with the cable slack? Does one click cause exactly one shift to the 2nd smallest cog? Adjust cable tension as necessary to make this transition work. Is the largest cog reachable with the final click? Is the guide pulley properly aligned with the bike in its lowest gear (front and rear)? Is the front derailleur cage rubbing in this lowest position*?

* adjust the 'L' to trim this contact out.

That should get you started. PG

SoSmellyAir

My guess is that you have dislodged the outer housing of the cable from where it enters into the rear derailleur, thus increasing the tension.

Don't just adjust the rear derailleur willy nilly; follow the Park Tool video on rear derailleur adjustment on YouTube.

Iride01 

Messing with the limit screws when something was working prior and only a cleaning was done is a definite misstep

At that point, I'd agree you need to go back to square one. If this is a Shimano DR then you can find the manuals for your model DR that tell you how to set it up. You need to look for the DM's. The DM for the DR will just give you the installation and initial set up and the DM for the shifter... I think, will have the adjustment procedures..

LBS's don't usually charge much for this if you don't need parts. So if you are just guessing what to adjust, then take it to a shop.

trailangel

Ya... Don't turn the bike upside down.

Troul 

is it a 3x 2x or 1x crankset system? Shift the crank into the biggest/largest diameter ring gear. It should allow the chain to settle into the smallest ring gear in the rear after you've achieved proper cable tension.

ClydeClydeson

As above, you skipped step a - y and unnecessarily did step z. OK, maybe that's exaggerating.

Steps for derailleur adjustment:

1. Confirm hanger alignment. If it worked previously and still looks fine and nothing to your knowledge has changed (no drops of rough handling) then proceed to step 2. If you think there might be a problem, bike shops have a tool for assessing the alignment
2. Without the cable attached, turn the cranks forward and use your thumb to manually push the derailleur all the way to the large cog and, while still turning the cranks, let the derailleur return to 'home' (smallest cog) position. If the derailleur can be moved to get the chain onto the largest cog but no further, and returns to the smallest cog without hesitation but no further, then the limit screws do not need to be touched. Seriously. Don't touch them.
3. Confirm the cable is correctly routed (eg. not hung up on cable stops as mentioned above), make sure the shifter has the highest (smallest cog, hardest) gear selected, pull the cable tight with your hand and fasten it at the derailleur pinch bolt. It should only require minor cable tension adjustments from there to get it perfect.

Oh, I almost forgot the most important point:
0. There is very seldom a need to flip your bike over - hang the bike by the nose of the saddle from a rafter in the garage or from a tree limb at an appropriate height. This way the bike is right-side-up and ergonomically correct for turning the pedals and operating the controls.
If you have ~$200 burning a hole in your pocket, an actual bike maintenance stand (like the park PCS series, although there are many others) is an instant life upgrade if you do your own wrenching.

sovende

I cringed at that part too! Additionally, WD40 isn’t my “go to” bike lube but used sparingly, it’s not likely to cause major issues. I will say that hosing the bike down with WD40 to the point that it drips enough to make the mess the OP described is definitely not recommended (IMHO).
While merely cleaning the chain is unlikely to cause the issue that the OP is reporting, I’m thinking that something occurred in the process of putting the bike upside down and has resulted in not allowing the RD to move through its full range. Before adjusting anything, I’d check for issues along the path of the cable housing i.e. housing not seated fully in stops (as already mentioned) or any kinks in the housing that could prevent full motion of the cable within.

Doug64

Regular WD40 is poor chain lubricant. Also holding a rag under your chain as you lube will catch drips. It only takes a drop of lobe on each roller to do the job.

Gandeloft

Hey everyone. I've followed all of the step-by-step instructions offered as they all say basically the same thing as the Parktool YouTube video on how to adjust the deraillour, which I'd gone through prior to opening this thread. I did additionally do it again following the guidance offered here alongside the video.

Turns out that the frame was f****** bent. The part of it to which the derailleur is mounted that is. I did not drop the bicycle nor did I scuff it against a wall or a something with the derailleur. What I did do is that I'd ridden a downhil track, bot not wildly. I didn't do any jumping (not higher than like, 5cm above the ground that is). I hadn't shifted to the highest gear after that until the next day. In that period, after the ride and before trying to shift into the highest gear, I did the cleaning, so I don't know if shifting into the lowest gear already ceased functioning after the ride but I suppose it is logical to assume so. I didn't treat it roughly during the ride, and it's my newest bike, none others (also hardtails) had issues after a ride down that specific track.
Why write all of this down? I'm afraid that my bicycle's frame is ****. How did it get bent when I've not hit the bicycle? I'm I'm afraid of needing to be afraid of doing proper riding on that bicycle. Here are some photos of the deraillour.

Nope. Haven't made 10 posts yet. Would've been nice to know in a more timely manner, before I'd invested 15minutes of my time into taking the photographs, uploading them and adding a text for them all.

I'll try to offer some description without the photos.
After I noticed two small scrapes on the derailleur, which I was unpleasantly surprised to find, I concluded that the scrapes happened when I'd ridden down a mountain at speeds of up to 90km/h by debris being shot from the front tyre. The scrapes I found were there a week before the malfunction. Since I've been told today that the frame was bent and that that is the reason for why the shifting couldn't have been sorted, I've concluded that it's also possible that I've been hitting some small plants with it.. But not a friggin tree stump or idk. what. So. How the hell did the bike's frame get bent? It the frame so soft that it couldn't handle the mere kinetic energy of the derailleur as I was doing a mild downhil ride? I don't know what to think.
P.S. I don't think that the mechanic who fixed my bicycle believed me that I didn't drop it. 😅

Additionally, I'll point out two things;
Some of you misunderstood me regarding WD-40. I did not and do not use WD-40 as a lubricat. I use it to clean the chain. The exact process is that I clean the chain thoroughly by spraying it and cleaning it of both the WD-40 and the dirt with an old shirt (which doesn't let off fibers) and then I leave it overnight after that step in order to give the WD-40 as much of a chance to fully evaporate as I can. After that, the following day that is, I lube the chain using bicycle chain oil.

Regarding not turning my bicycle upside down;
It's a pet peeve thing. You do you.

I appreciate all of the replies.

I've edited the message to fix the heap of grammar misshap it had.

Crankycrank

That part is called the derailleur hanger and all kinds of things can tweak it out of shape so don't sweat it too much. I bent one slightly once by ham fisting a wheel into the dropouts with the chain on the wrong cog not to mention the various bumps from bike racks, falling over, etc. Just get it aligned and enjoy the ride. I don't understand this objection to turning a bike upside down. No it's not a good thing to do when adjusting derailleurs, or when you'll damage parts on your handlebars such as shifters, electronics and cables or setting it on a gravel road where things get scratched up, or muddy holes, or the side of a steep hill, or in a dog park, if you get my drift. When I get a flat tire I'll look for a patch of dry grass or one of those kids playgrounds with the rubber surface, or the homeless very thoughtfully sometimes leave some pieces of clothing around for me to set the bike on, or the carpet in my apt., or ??, to turn it upside down. No worries.

Iride01 

Derailleur hangars are usually replaceable and inexpensive. The hangar is intended to be weak so that it bends before damaging the more expensive DR or bike frame. So just letting the bike fall on the DR or something firmly bumping the DR while the bike was in the garage or where ever you store the bike.

Was this a mail order bike? Might have happened during shipping. But if it was previously working correctly, then probably not.

Gandeloft

Regarding the derailleur hanger bending; I've never had it bend like that before, and this bike's been in my hands for mere two weeks exactly today, so the problem occurred after only a week and a half of ownership and use.

Regarding turning the bicycle upside down; Nothing gets damaged by doing so, it only touches the ground with the seat and the grips on the steering column. And yeah, I don't exactly drag it into place on gravel while it's upside down 😄

Gandeloft

I don't know of a possibility for it to have been bumped at the derailleur. I keep it inside of my flat (I'm all alone currently) when it's not in use and it never fell anywhere else.
This is the first time though that I'm hearing that the derailleur hangar is supposed to be replaceable. I mean, it does seem to be a seperate part from the frame.. That makes sense and knowing that it can be replaced calms me down. Thanks on the info.

Yeah, it was previously working correctly, and no it wasn't a mail order bike. I'd gone to the store to pick it up after assembly.

trailangel

Ok, Gandeloft..... turning the bike upside is not a pet-peeve thing. You did You.. and turned the bike upside down and the excess WD40 dripped downward on your brakes. ... if it was rightside up it would have dripped onto the ground.... or better yet the dirty shop rag you should be using to catch the overspray.
If you had a bike with a $200 leather saddle on it.....you would understand the "don't turn bike upside down" statement.

cobba

Your photos are here.....

https://www.bikeforums.net/g/album/22107142

Iride01 

You seem to be upset defensive that we suggest the bike may have fallen or gotten bumped on the derailleur bending the hangar. We don't care if you did or didn't. Maybe someone else did while you weren't looking or some weird alignment of the planets and nearby crystals focused the tidal forces of the moon on your DR and bent the hangar. Doesn't matter who or why the cause.

What you need to do if nothing else fixes your issue first is have the DR checked by a shop. Sometimes a very imperceptible bend in the hangar can make a big problem for DR's. A shop will have a tool that can tell them if the DR hangar is bent.

Charliekeet

The good news is you've learned re: the hanger, which is most definitely replaceable, inexpensive, and normal to have to be replaced or straightened (and that's much better vs. the actual frame having the issue). And you've learned that spraying stuff has to be done carefully. We've all done it, and gotten stuff we didn't want on something else- tires, seat, grips, etc...

Gandeloft

Lol what is going on 😃
I had to delete the link from your comment in my reply to it in order to avoid the "you have to have 10 posts in order to post links" thing, as I got it when I initially replied to your comment.

veganbikes

The whole idea is to prevent spammers and also encourage people to actually get involved with the forums rather than just using us like ask Jeeves or googles or alta vista or whatever. It makes less work for the moderators to have this stuff in place because they have a tough job enough already so if you want to post links and photos just join the forum. I don't mean post in your own thread I mean contribute all over the forum. Share your experiences and passion for bikes if you have it.

ARider2

I am often surprised at the high cost of derailleur hangers. They often retail for about the same as a cheap Shimano Tourney rear derailleur.

Iride01 

You do have a point, but the OP's DR is a Shimano XT M8100. He can buy 5 or 6 hangers for price of that one derailleur. Maybe more.

I might be wrong, at least I think this is the OP's bike,


https://www.cube.eu/en/2022/bikes/mo...rsebluenblack/