Philatio

I'm sorry for starting a thread about this, I know these aren't alot of fun and involve alot of guess work since you can't actually hear it and have to rely solely on my description. But I've tried everything I can think of and it just wont stop.

Here's the deal, I've got a 1x6 on a road bike with no FD. When I'm pedaling, particularly when I'm pedaling hard but not exclusively, it knocks erratically. It sometimes seems vaguely related to my pedal stroke but not always. It doesn't sound when the drivetrain is not in motion.

I've tried or checked:

• Chain ring bolts
• Spoke tension
• Greasing spoke crossings
• Tightened/adjusted RD
• Tightened cartridge BB
• The "test" without the chain on where you spin the cranks and make sure the BB is still good
• Tightened crank arms
• It's a freewheel hub, and I've replaced the freewheel
• Repacking the rear hub
• Checking for a tight link in the chain
• Checked wheel clearance - like the brake pads hitting or something
• Changed the pedals, made sure they were greased and tight
• Checked my rear rack for movement - it's extremely solidly connected (can lift the bike with no movement) so I don't think it's this but it's not absolutely ruled out.

I have short stack chain ring bolts on. I've considered that while tight they might still be a little long with a multispeed chainring as opposed to one made for singlespeed setups. I don't know if there are standard thicknesses or not. I'm planning to throw the outer ring on with the original bolts to confirm this.

I'm trying to get a hold of another rear wheel to rule out the wheel.

I think I'm going to try taking the cartridge BB all the way out and regrease/thread it just to be sure.

Just wondering if anyone has any other ideas of what could possibly be doing this.

vpiuva

I would do the rear wheel swap like you're going to do to narrow it down to the crank area or rear wheel. Let us know how that goes. Sounds like a bearing gone bad somewhere. Or maybe a bent rear axle could cause this noise?

Philatio

I checked the axle for bending too, it was eyeball straight. I've really thought it sounded like the chainring bolts the entire time, but they're completely tight and I just don't see how it could be them.

Hopefully I'll get a hold of the other wheel tonight or tomorrow.

Philatio

Well it looks like I'm not going to be able to replace the wheel after all. I think that was kind of a long shot anyways considering I've checked the entire wheel over (freewheel, spokes, hub, cracks in the rim).

I took some channel locks and tried to wiggle my chain ring. I'm pretty convinced it's not coming from there, it's very firmly connected.

I guess my last hope or idea is that my cartridge BB needs to be regreased or something. It was properly tight before though when I checked it. I think it's unlikely honestly but it's the only thing I haven't double checked.

To sum it up, the noise is a sporadic knocking sound that "seems" to be coming from the rear wheel. It sometimes is vaguely corresponding to pedaling, but not always. I'll hear it about 1/2 the time I'm pedaling. It definitely gets more frequent the harder/faster I pedal, and is completely silent when I'm coasting. Oh yea, and it's driving me crazy

greyghost_6

Knocking usually comes from the bottom bracket in my experience. Maybe the cardridge is too tight. I recently installed a DA octalink too tight and am getting some knocking, I couldn't hear it when I was riding though, just on the stand. I would re-check the BB, and since it doesn't happen when you are coasting, that rules out your rear and front wheels. Plus buying a new bb is way cheaper than a new rear wheel. If that still doesn't work just take off your rack and see if that helps, your seat might just be moving (depending on how its mounted) and is scooting around and knocks when it gets into its original position. Let me know if any of that helps.

Philatio

definitely useful feedback. I hadn't considered the seat at all actually. I'll try going at my BB again tonight and I'll check on the seat as well. Thanks alot - I'll post how it goes.

Philatio

Ok, I checked on the seat. It's secure, and I can reproduce the noise when I'm standing and pedaling as well as sitting so I think I can rule that out.

I just got done pulling the cranks and BB. Regreased everything and reinstalled. The noise still is going. At this point I'm pretty much out of ideas, I think I might just take it into a lbs.

Philatio

Update: I found a wheel to borrow that fit reasonably well - I was unable to reproduce the noise with the second wheel. So, it's something in my wheel.

Again, it's a 6 speed FREEWHEEL, 32 spokes. Spokes are all tight. Cones have the slightest play without the quick release - no play when mounted. New Shimano freewheel - the one I replaced made the same noise too.

Could my spokes all be too tight/too loose? I don't have a tensiometer (?) so it's relatively roughly done. However I had them in the same ball park for 1000's of miles before the noise started.

When pedaling it will knock several times per revolution of the cranks when it is making the noise. I would estimate about 1/2 the time I'm pedaling it's knocking. I know that that is usually a bottom bracket, and for thoroughness I'm going to pull my cartrige and put back in the adjustable cup.

operator

You haven't ruled out the headset/fork/loose cup in headtube yet.

probable556

Do this ASAP. Trust me. Try with the front too.

Philatio

See my last post before this - I managed to get a hold of a rear wheel and the noise seemed to quit. I think this indicates that it is more than likely the rear wheel, but it's not necessarily conclusive (maybe the noise needs to be "warmed up", maybe the new wheel was stressing something differently, etc).

I haven't tried a front replacement, I think that's kind of a stretch. I'll see what I can do though. Thanks

Philatio

I've checked that it's properly tight and turns smoothly and whatnot, I haven't dismantled and checked everything though. I'll give that a go if replacing the BB doesn't do the trick.

operator

You should do this first before bothering with the BB. If something is cracked in the fork/race area, you're looking at a new face not a new BB.

Philatio

Can't find any cracks anywhere, everything in the headset and head tube seem to be alright.

I replaced the cartridge BB with an adjustable, the noise persists.

operator

Try swapping the pedals out.

I think what you have to do now is to start swapping components until the noise disappears or you find the cause.

Philatio

swapped the pedals already - no change.

I think I'm going to buy a new rear wheel, it seemed to go away with a different wheel. The thing I can't figure out is what is causing the noise. I've checked over the whole thing, and the only logical thing it could be is a loose spoke or spokes, and they're all good.

I've been meaning to switch out the freewheel for a freehub for a while anyways.