tsappenfield

Disassembled my Colnago Mexico and sent it off to the paint shop. Got it back, reassembled it and took it to my bike shop for a final tune-up. The drive-train is Campy Super Record marked 1984. It's a twelve speed. When I took it for the first test ride, I heard what I would decribe as "chain rub" coming from the front derailleur cage, or so I thought. It did not matter what free wheel cog I was in and it occurred only when the chain was on the small chain ring. I tried to "trim it out", with no luck. The noise never occurred when I pedaled with no load (tension) and I couldn't reproduce it when the bike was on my workstand. But once I exerted some pressure on the system while pedaling hard, the noise appeared. The final observation (this is a biggie) was when the chain was on the 3rd or 4th cog where there was plenty of distance between the derailleur cage plates, the noise was still there. So it doesn't appear to be rubbing against the derailleur cage wall(s) at all. By the way, I don't rememer this problem prior to tearing the bike down.

I took it back to the local bike shop mechanic and he felt that since the teeth on the small chain ring showed little wear, that maybe this noise is coming from the chain trying to settle in on the chain ring teeth. He thought that riding the bike would eventually eliminate the problem. I'm not buying this. Any thoughts?

chizhang001001

check your wheel hubs, if the noise comes only during hard climbing it could be a bad front hub, happened to me before, took me forever to figure it out

JohnDThompson 

Check the chainline. If it only happens in the small ring, it could be that the crank is too close to the frame, causing the chain to scrape on the inner aspect of the outer chainring. Perhaps the asymmetrical BB spindle is installed backwards?

due ruote 

I was going to guess cross-chaining and the chain rubbing on the large ring, but if it's happening on all cogs, I don't see how that's it.

Are you using the same BB as before? Is it assymetrical and did you put it back in the same way?

Did you change the chain? How about the freewheel?

If it's not a new chain, I'd probably try replacing that first and see what you get. Then maybe try a different freewheel. Just do one thing at a time so you can ID the culprit.

JPZ66

The way some unscrupulous bike shops operate....is it even the original Campy BB that got put back in ? (or did they swap a cheap part on ya ?) one shop nearby was caught doing just that recently.....taking out the good stuff that some owners never notice, selling them on ebay, and swaping in inferior and cheaper parts....
just sayin'

due ruote 

I believe the OP said he assembled the bike and took it to the shop for final adjustment - do I have that right?

JPZ66

Yes, I stand corrected....OP did say he assembled the bike! Well, let it serve as a warning to those who rely on LBS to assemble things......

shoota 

This is a little off-topic but OP has a stand, can assemble a bike from parts, but has to take it to a LBS for a "final tuneup"? Maybe the lbs screwed something up, or maybe the OP did..

jiangshi

FD rubbing on crankarm?

Velognome 

If the noise appears under a loaded condition only, I'd check the BB as JDT suggested and I'd add to that the cranks, might be loose? I'd also check the frames alignment, it may have gotten wacked at the painters or during shipping to and fro.

seedsbelize 

I have this issue on one of my bikes, and I've never been able to figure it out. I now try to just ignore it.

20grit

String on the rear dropouts/around seat tube to check alignment? Maybe the rear triangle got bent to the drive side at some point? Chain could be rubbing the inside face of your bigger chain ring.

Pars 

Could the chain be rubbing on the cage cross piece on the FD? If the FD is installed too high, could explain only in the small chainring. Although the OP said it did it in any rear gear, so that probably isn't it.

due ruote 

The way I've done this it's been string around the head tube, tied to both dropouts, measure from the string to the seat tube; both sides should be equidistant.

Photo from Harris/Sheldon Brown https://sheldonbrown.com/frame-spacing.html#symmetry :

20grit

I guess I should have been a little more clear, I measure both ways, for various reasons.
I prefer seat tube because it allows me to more precisely measure from where the string breaks contact with the tube. I end up measuring length of the string using this method. If one stay is spread more widely than the other, it will break from the seat tube closer to the front of the bike.
The head tube method allows me to make errors not holding my measuring implement perpendicular to tubes.
Using that other method, I measure per Sheldon.

Flaws in the lengths of stays can cause wonky results with both. I have a fork with uneven blades that threw me off on alignment for a very long time.

jiangshi

I use this:
https://www.amazon.com/Park-Tool-***-.../dp/B000WYCHJG

tsappenfield

I'm trying to figure out how to respond to all of the questions. First of all, same bottom bracket, same freewheel, and same chain. I'm pretty sure that I reinstalled the bottom bracket correctly. The frame was not sent back to me by the painter; I picked it up as the painter is just two hours away. I will check frame allignment and check the cranks. Maybe the cheapest and easiest thing to do first is to change the chain. Again, what's curious to me is that I'm 99% sure this noise wasn't present before the teardown, although I would admit that I didn't ride the bike that much before sending it off to the painter and my hearing isnt what it used to be when I was younger.
TSAPP

rootboy 

Wondering if the paint shop could have "bumped" something out of alignment. Dropout hanger?

sloar

i had this problem on a bike i just picked up. i could not figure out what the noise was. same problem your having. then i noticed the chain was not sitting firmly on the chainring. it was riding across the very top of the teeth and not sitting down tight. swapped chains and fixed the problem.

tsappenfield

I checked out the rest of the possible sources on noise yesterday and I think I have visually eliminated all of them. I still haven't switched out the chain. I'll look at the dropout hanger today.
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Michael Angelo 

Always start with the basics. Make real sure the fixed bottom bracket cup is tight, real tight. Then make sure the BB is installed correctly. Then make sure the crank bolts are tight, I take a crank bolt wrench with me on every first ride double checking both bolts every 10 miles or so. Also are the chainring bolts tight? Make sure the basics are covered before going any further.

gomango

This is my plan as well.

Recently I had a clicking coming from the crank area on my newest Kvale.

Did exactly as recommended here but still couldn't find it.

I took a flying guess and decided it could be a worn cleat and sure enough, that was it.

Basic checklist first is the rule though.

jimmuller 

Does the sound always occur in the same place in the crank rotation?

Check the chainring bolts. And the crank bolts. And the pedals. I had a noise like that, turned out to be a pedal not tightened into the crank.

Or it could be the frambulator. Yeah, the frambulator. That's gotta' be it.

degan

+1 This is what I was going to suggest. I had a similar problem on an old mtb I use to have. It was also ghost shifting under certain circumstances, but the hanger was bent pretty bad. Yours might just be off by a little bit.

tsappenfield

I have to come clean on something. I did not reinstall the bottom bracket and headset. No torque wrenches, so I left that to my LBS. I have checked the chain ring bolts and none were completely tightened down. One of the bolts was stripped. Actually the bolt was okay, but the receiving hole in the spider was stripped. I also noticed that the lettering on the inner chain ring faced in rather than out as on the large chain ring. Would that make a difference? I'm going to replace the chain today and see if that corrects the problem.
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