Nigeyy
Legendary Member
- Location
- Massachusetts, USA
So about a week ago, my current commuter bike (1976 Raleigh Super Course with updated components) started making some knocking sounds. Initially it was noticeable, but not too loud...... then it got louder and more frequent.
OK, it only happened when I pedaled under load, but mysteriously would go away, and then come back. It seemed to be coming from the bottom bracket area. I quickly reasoned it down to one of 4 things: i. bottom bracket, ii. freewheel, iii. chafing of a component, or iv. (gulp) frame failure.
With a heavy heart, I first set about with the potentially fatal one: potential frame failure. Fortunately, and after a detailed examination, I could not see any cracks, loose tube joints, etc. A big relief. Now I was faced with a problem; up on the stand and try as I might, I could not replicate the knocking noise. No components were chafing, chain in good condition, gears aligned. I noticed the headset was ever so slightly loose, so I tightened that up a bit. I inspected the brakes, again no problem. Seatpost clamp is good, nothing else loose. In a faint hope that I had somehow fixed it just by the miracle of looking at it and tightening a few things (and buoyed by the fact I was comfortable it was not a frame problem), I cycled into work the next day..... same thing after a couple of miles, if a little worse.
After some thought during the day, I wondered if there was something dislodged and fallen down the seat tube that was somehow knocking up against the bottom bracket. That night, I was determined to find the issue -and I'd worked myself up into a mechanical diagnosis frenzy -I had to take the bottom bracket out to inspect anyway, so I bet that was the issue... in fact, by the time I was cycling home I was convinced and close to patting myself on the back as it was surely the cause. Later that night I took out the bottom bracket -nothing in the BB frame area -it was smooth as silk. OK, maybe it wasn't that. I took off the freewheel and inspected it -again smooth as silk. OK, I was getting desperate -I took my wheel bearings apart, inspected the axle, repacked, and put it back together.
But the next morning brought me renewed optimism! I cycled (silently) the 6 of 8 miles into work -but then about 7 miles in, you guessed it...The noise was back. Again, another day at work wondering. OK, let me think..... only under load, puzzlingly unable to reproduce it on a stand.... Wait a minute -the mudguards and pedals! Surely it was the mudguards that could be rubbing under load? Or a bad pedal? Yes, that was definitely it my feverish mind thought (conveniently forgetting that I couldn't feel any roughness pedaling at the pedals, plus the fact I had good clearances for the mudguards. Later that night I took the mudguards off, and put another set of pedals on.
The next day: you guessed it.... OK, now I was desperate; the noise was even worse and more frequent. And looking like a demented cyclist I'd tried pedaling softly under load, hard, backwards then forwards, changing gear, steering one way then the other, all in an effort to try to isolate a cause. This is killing me! Again, at work my mind works overtime. It had, I mean had, to be the bottom bracket right? Maybe the bottom bracket was bad, but felt good under no load? Yes, that had to be it. It must be. That night..... I looked in my spare parts drawer and found a couple of spare BBs, but alas both were not the right size. However, I thought I'd take the opportunity to inspect it again. And again after removal, it seemed perfect.
At this point, my reasoning was now down to the bottom bracket or the freewheel (had to be surely, as it was only when I pedaled forwards). I decided to refocus my energies now on the freewheel as I had no choice. I took it off, and sure enough, it was smooth as silk. Not a trace of roughness. At this point I've decided I might as well take it apart, clean it, and relube it. I go to the lock ring -and guess what? It's pretty loose. How did I miss that?
At long last... the offending article. Here is a tangible thing I can see that may be causing the issue. I strip the freewheel down, clean, relube, tighten up the lockring. The next day -no noise, at all! And so far so good.....
The strange thing is that the freewheel didn't feel loose or notchy in anyway -I can only assume the extra space caused by the loose lockring allowed a BB to jump out every now and again, but only under load. So the moral of the story is for freewheels, don't forget to check your lockring tightness! (now I've got to put my mudguards back on, as well as my old pedals).
OK, it only happened when I pedaled under load, but mysteriously would go away, and then come back. It seemed to be coming from the bottom bracket area. I quickly reasoned it down to one of 4 things: i. bottom bracket, ii. freewheel, iii. chafing of a component, or iv. (gulp) frame failure.
With a heavy heart, I first set about with the potentially fatal one: potential frame failure. Fortunately, and after a detailed examination, I could not see any cracks, loose tube joints, etc. A big relief. Now I was faced with a problem; up on the stand and try as I might, I could not replicate the knocking noise. No components were chafing, chain in good condition, gears aligned. I noticed the headset was ever so slightly loose, so I tightened that up a bit. I inspected the brakes, again no problem. Seatpost clamp is good, nothing else loose. In a faint hope that I had somehow fixed it just by the miracle of looking at it and tightening a few things (and buoyed by the fact I was comfortable it was not a frame problem), I cycled into work the next day..... same thing after a couple of miles, if a little worse.
After some thought during the day, I wondered if there was something dislodged and fallen down the seat tube that was somehow knocking up against the bottom bracket. That night, I was determined to find the issue -and I'd worked myself up into a mechanical diagnosis frenzy -I had to take the bottom bracket out to inspect anyway, so I bet that was the issue... in fact, by the time I was cycling home I was convinced and close to patting myself on the back as it was surely the cause. Later that night I took out the bottom bracket -nothing in the BB frame area -it was smooth as silk. OK, maybe it wasn't that. I took off the freewheel and inspected it -again smooth as silk. OK, I was getting desperate -I took my wheel bearings apart, inspected the axle, repacked, and put it back together.
But the next morning brought me renewed optimism! I cycled (silently) the 6 of 8 miles into work -but then about 7 miles in, you guessed it...The noise was back. Again, another day at work wondering. OK, let me think..... only under load, puzzlingly unable to reproduce it on a stand.... Wait a minute -the mudguards and pedals! Surely it was the mudguards that could be rubbing under load? Or a bad pedal? Yes, that was definitely it my feverish mind thought (conveniently forgetting that I couldn't feel any roughness pedaling at the pedals, plus the fact I had good clearances for the mudguards. Later that night I took the mudguards off, and put another set of pedals on.
The next day: you guessed it.... OK, now I was desperate; the noise was even worse and more frequent. And looking like a demented cyclist I'd tried pedaling softly under load, hard, backwards then forwards, changing gear, steering one way then the other, all in an effort to try to isolate a cause. This is killing me! Again, at work my mind works overtime. It had, I mean had, to be the bottom bracket right? Maybe the bottom bracket was bad, but felt good under no load? Yes, that had to be it. It must be. That night..... I looked in my spare parts drawer and found a couple of spare BBs, but alas both were not the right size. However, I thought I'd take the opportunity to inspect it again. And again after removal, it seemed perfect.
At this point, my reasoning was now down to the bottom bracket or the freewheel (had to be surely, as it was only when I pedaled forwards). I decided to refocus my energies now on the freewheel as I had no choice. I took it off, and sure enough, it was smooth as silk. Not a trace of roughness. At this point I've decided I might as well take it apart, clean it, and relube it. I go to the lock ring -and guess what? It's pretty loose. How did I miss that?
At long last... the offending article. Here is a tangible thing I can see that may be causing the issue. I strip the freewheel down, clean, relube, tighten up the lockring. The next day -no noise, at all! And so far so good.....
The strange thing is that the freewheel didn't feel loose or notchy in anyway -I can only assume the extra space caused by the loose lockring allowed a BB to jump out every now and again, but only under load. So the moral of the story is for freewheels, don't forget to check your lockring tightness! (now I've got to put my mudguards back on, as well as my old pedals).
