Bicycle Mechanics - Sound from rear mech when pedalling out of te saddle
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09-07-11, 04:46 AM
I have a Cannondale supersix with shimano 105 equipment. When I'm off the saddle and pushing hard, I can notice a sound that's coming from the area of the rear mech. It sound like something was rubbing against something, a chain for example. I can't really see anything being wrong when I look at the derailleur and I have no clue what could be causing it but it is pretty annoying. Does anybody have any idea what could be causing it? Thanks
09-07-11, 06:34 AM
might be the wheel being too soft and the rim rubbing against the brake pad
09-07-11, 07:37 AM
I was thinking about that too and my friend remarked today that it did sound like the brake pad rubbing against the rim, but he wasn't sure. I have Mavic Aksium rims.
The pads are a just a tiny bit decentred, so I'll try to adjust that, but there is still several mm's of clearance.
09-07-11, 07:39 AM
maybe open the brakes as you would change the wheel and give it a try ..
09-07-11, 07:55 AM
Hey, I just tried that and it isn't the brakes.The sound is still there. It's hard to describe the quality of the sound - it's kinda weak, almost like some metal was very slightly vibrating or the like. It's kinda annoying and it's been constant for the last couple of thousand km's. I just don't know if it is normal or not
09-07-11, 08:09 AM
is it appearing in certain gears only? like small front, large rear?
09-07-11, 08:13 AM
no. it's just there when i really put the pressure on in the hills or hard sprinting.
09-07-11, 08:28 AM
the last thing i can think about if you say you cannot describe the quality of the sound, is still coming from the wheel, spokes this time. the crossings.
i had that problem with my fulcrums and it took me quite some time to figure out what it was. it's a silent clicking sound? if yes, that's the spokes contacting while the load on the wheel changes as it's spinning. if so you just apply some light oil or grease between the crossing and it's gone.
09-07-11, 08:48 AM
First of all thank you for your quick responses and advices (forgot to say that before :) )
The sound when it last is pretty constant and lasts for a short time. It get's most pronounced on the finish of the downstroke that's done on the opposite side and it is only audible on that opposite downstroke, - it's not really clicking, that's why I thought about the chain rubbing or similar. My wheels have aero spokes. I tried spraying them with chain lube, but the sound persists. it's quite strange
09-07-11, 09:06 AM
not a problem .. i would return to the shop where you bought it and have them have a look. without actually hearing it it's kinda hard to determine ;)
can be anything from the cranks, pedals, even the cleats on your shoes. unfortunately, there are a lot of potential sources of all kinds of weird noises on any bike ..
09-07-11, 09:15 AM
Yeah, i know, sounds on a bike are a PIA to figure out. Actually the store is quite far away. I'll have the bike serviced by a local serviceman at the end of the month or in the beginning of October and I'll ask him to check up on that as well. (I do doubt that it's the cleats, it's not that squeaky kind of a sound, it's more like, as I mentioned, like that something was loose andvibrating just a tad, but the mech seems quite secured and it's oiled quite nicely as well).
It's just freakin' annoying on days when I don't have my mp3 player with me :) I think that it's nothing serious, othewise the bike would've probably fallen apart months ago; it's just strange, because it's a new bike (three months old) and has just over 3300 km on it.
09-08-11, 06:37 AM
I just spoke to a head of my LBS today. He said that it might be the case that the rear derailleur is not set correctly and that therefore the chain could rub against the cage. Can that be the case? What is set improperly if that is so? Is it just the cable tension, or is it something else that might need tuning?
09-08-11, 06:45 AM
Yes, could be. Switch to the biggest cog and check whether the upper derailer pulley wheel is in line with the cog. If not, it needs fixing via the set screws on the derailer. be careful here, if you turn the wrong direction and you switch to the lowest gear, the chain might fall behind the cassette and do some serious damage there.
There are tons of vids on youtube if you look for "rear derailleur adjustment road bike", like this (http://www.youtube.com/watch?v=ZRAtxmLjrLs). You also might want to check if the derailer hanger is bent inwards (when looking from the rear wheel towards the front wheel).
09-08-11, 07:29 AM
This is the derailleur hanger; it seems ok?: http://imageshack.us/photo/my-images/69/dsc0216db.jpg/
09-08-11, 07:53 AM
http://www.parktool.com/uploads/images/blog/repair_help/DAG03.jpg this is how it shouldn't look like, drastically. found this (http://www.williambenedict.com/bikes/derailleurs.html) and that (http://www.bikeradar.com/gear/article/workshop-troubleshooting-shimano-gears-18244/), too. but the picture seems ok.
09-08-11, 08:03 AM
Thanks a lot for all the links and replies. I''m gonna definately check them out in more detail! I also think that the alignment is perhaps okay (the jockey wheel might be a 'tee-wee' on the inside, but I'm not really sure, it's really hard to tell).
I have a medium long ride tomorrow, but I think that in the end I'll probably just phone a guy I know who knows a lot about servicing bikes on sunday and ask him if he could take a look at it (and then also ask him how I can fix it myself in the future), cuz this thing is taking way too much time (I have a lot of work to do also for school). I hate them noises on them new bikes :D
09-17-11, 03:13 PM
I had the bike serviced and the guy said it was the front derailleur; the chain was supposedly rubbing against it. I said to myself - that's great, problem solved. But I noticed on the uphill that the noise is still here, although a little less than it was before. I can still hear it, when I'm pedalling hard out of the saddle and now that my attention is focused on the FD, I do think that it's plausible that the sound comes from there. It is also more obvious when the bike is ridden in a way that it is rocked left-to-right laterally than as opposed to when I ride in a way that I turn the handlebars left and right more while out of the saddle. Also I do believe that it produces the noise when the chain is in the bigger cogs on the back. And I also suspect that the noise that I can hear while sprinting has more to do with the fact that the bike has aero spokes than with the problem that I'm describing (rather poorly I admit, but it is a hard to describe sound and English ain't my first language :) ) in this thread.
The guy said that I should bring it back and he'll take a look at it some more, but I just wanted to furether 'clarify' the problem in case if there are any new ideas about this problem. Do you think that it might be due to my pedalling style that this happenes (although I don't have this kind of problem on my MTB), or do things just need some more adjustment?
09-26-11, 03:41 AM
Ok, just another update. I had the bike checked out again and was told that it is mostly likel a problem in the hub. SInce the bike is under warranty and the hubs are sealed I had to take it to an authorized service. I'm waiting on what they will be able to find out.
I', just curious if anyone can explain to me what problem in the hub would be causing noise when the bike is under stress and leaned in one particular direction?
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