Knocking noise.

[compo]

Looking for ideas and suggestions please.

I have just rebuilt a 1980's vintage road bike. It rides well apart from an intermittent knocking noise. It'a definate knocking noise, not a clicking or tapping noise. It tends to come on when I am putting pressure through the pedals and stops when I stop pedalling and just freewheel, so the problem is obviously with the drive train. I cannot feel any knocking when riding, just hear it. I tried micro adjusting the gears with the lever in friction mode and that made no difference, and in Index mode they index OK. So, that leaves pedals, cranks, or bottom bracket. On the rebuild I fitted new pedals (budget ones), and a new Shimano bottom bracket. I also fitted a used rear mech, this one, http://www.ebay.co.uk/itm/SHIMANO-REAR-DERAILLEUR-/181112380861?_trksid=p2047675.l2557&ssPageName=STRK:MEWNXT&nma=true&si=uStxLtUQrJwxns1XZOCijrNdFZ4%3D&orig_cvip=true&rt=nc I am wondering if there are compatibility issues as I am using it with a 6 speed freewheel.

When I fitted the BB I greased the metal collar but left the plastic one dry which I believe is correct and I fitted the cranks dry onto the tapers.

I can fit a pair of known good pedals to eliminate them, but my gut reaction is that it's the BB. It is a BB-UN26. I have a semi sealed unit I can fit if necessary to try it before forking out for another BB unit.

 

[fossyant]

I tend to fully grease all parts of the cartridge bearings, including plastic sleeve and the cranks/axel. Give that a go first, also check chain ring bolts.

 

[compo]

Yesterday I swapped out the BB for a new semi-sealed job, no difference to the noise. I fitted known good pedals, no difference to the noise. I have now replaced the fully sealed BB and the new pedals I had for the bike. One thing I did think about was that I fitted a new quill stem and fitted it dry, and the handlebar clamp I left dry. I have now greased the stem and the clamp but haven't checked it yet as it is persisting down with rain. Also, although I greased the seat post I didn't grease the saddle/rail fittings, which I will have to do. I am wanting to change the seat post to a micro-adjust one. I did dismantle the chain rings to clean them and reassembled them tightly. Should I have greased the bolts and spacers on reassembly? They are steel chainrings, the original Raleigh fitment.

I had the frame powder coated before reassembly and there is no sign of cracking in the paint around the lugs so I think I can rest easy that the frame isn't cracked.

 

[Spoked Wheels]

Mmmm my best guess is that a ghost is knocking inside the downtube - let him out and that would solve your problem.

 

[tyred]

I have experienced knocking noises from freewheel blocks when taking up drive, especially if trying to accelerate out of a junction or something. I'd try working a little light oil into it.

 

[compo]

I bet when I find the cause, and I will eventually, it will be something so obvious I will be kicking myself.

 

[numbnuts]

it will be something so obvious I will be kicking myself.

Can we come and watch
it sounds like you have covered everything, bar immersing the whole bike in grease and oil, I can't think what else it could be.
Have a look at this
http://www.jimlangley.net/wrench/keepitquiet.html

 

[RWright]

Bad jockey wheel maybe?

 

[smokeysmoo]

Is there someone at the door?

 

[mark st1]

Your Hip ?

 

[Steve Malkin]

I once had a similar problem which was only evident when putting a lot of force through the pedals and I eventually tracked it down to a slightly bent rear axle. That could definitely be felt through the pedals as well as heard though so may not be the cause in your case.

 

[BigonaBianchi]

in my case recently it was the crank catching my pump on the downtube

 

[compo]

Thanks for all the suggestions. I can't see why it should be playing up when pedalling rather than when freewheeling but I am going to try a different freewheel on later today, one I removed from a wheel and know it is OK. It's only a 5 minute job to swap them over and may be another possible cause eliminated. The wheels are new, and before fitting them I stripped and repacked the bearings so I know all that side of things is OK.

 

[Gary E]

If there's anything that will finally drive me away from this bike riding stuff it'll be random clicking/knocking noises. Good luck with your investigation and please let us know when you finally solve it (or let us know when the bike goes up on eBay )

 

[compo]

I think I may have it sorted. I fitted an old freewheel on the wheel, went for a ride and no noise. So I then fitted another old freewheel with the same result. I then refitted the original new freewheel that I had on when the knocking occured and rode a couple of miles and there was no noise. Why removing the freewheel and refitting it should make any difference must remain one of life's mysteries. It will take a few miles before I claim complete victory though!