Bottom bracket creak hell

This is one of the great undiluted joys of being a bike mechanic, which I'm not by trade but am by about 28 years practice.
My Thorn Raven developed clunkiness in Bottom Bracket so I deduced that it needed to be replaced. It is in an eccentric bottom bracket shell as it has Rohloff gears. I replaced it and clunkiness disappeared but in first spin out I noticed a creak from the bottom bracket area. Now there are legion causes of this, so I stood up. It persisted. Not the saddle or seatpin then. I noticed that it happened only with pressure on the left pedal.
Came home. Tightened pedal. No good. Tightened crank. No good. Took off pedal and crank, greased them, refitted. No good. Pedal was fairly new, so I put another one in. No good. Tightened eccentric screws which keep eccentric in position. No good.
Hmmmm.

Maybe it's the crank, as I'd had a little trouble with a crankpuller when replacing Bottom Bracket and slightly damaged it. Took crank off old bike and swapped. No good.
There's only one other thing that I can think of, but I did tighten them recently. Chainring bolts. Ah ha!!. Two were slightly loose. Eureka. Fixed. The creak is gone and I am not up the creek!
It only took me about 2 hours..

The lesson must be this, something I didn't know before. A left pressure creak, think of chainring bolts.

7 comments on “Bottom bracket creak hell”

  1. Patrick wrote:

    Why did the chainring bolts come loose? Do you use a torque wrench? I have one and I use it whenever possible, and especially where the torque setting is marked on the component or in the instruction sheet.

    As it happens, there's a rattle somewhere on my tourer since I swapped over the wheels after Denmark and took off the pannier racks. It sounds like the front mech but it happens only when the chain is on the two smallest sprockets. I can feel nothing loose anywhere on the bike. All I can think of is that because I've inflated the tyres up very hard, this is a 'normal' rattle I shouldn't bother about. Honestly, there is nothing loose on my bike!

  2. Garry Lee wrote:

    I actually have a torque wrench but only very recently and I've yet to use it in anger!. I'd tightened these good and tight, as we say. Don't know why they loosened. It's not something that often happens. Your rattle COULD be that the cassette retaining nut thing (the one you put the tool on to tighten the cassette) is loose. I've often had that. I presume you've a cassette system? Even God can't keep them tight in some cases!

  3. Chris wrote:

    My cassette locknut came undone after I fitted a custom cassette. I didn't hear a noise, but it felt strange and I looked down to see the sprockets appear to wobble. One to look out for. I didn't torque it, but I made sure it was tight enough the second time.

  4. Patrick wrote:

    Nice one! There was something loose on my bike after all. The cassette locknut as suggested. Only a bit loose but loose. The rattle has gone. There is still a slight amount of play in the cassette though. Sandra's is the same. I assume that is the freewheel on the axle, as the locknut is now very tight.

  5. Chris wrote:

    I upgraded my external bearings (on a Sora chainset, but actually Tiagra external cups) with Ultegra and fitted SPD SL pedals. Still – as with the set I replaced – a creaking when I was out of the saddle and putting pressure on the pedals going uphill.

    When I was about to set off from Patrick's house on a ride around the West Pennine Moors I noticed that the nearside crank was loose. I had brought my toolbox so I tightened up the "dustcap" with the little knurled tool and then borrowed Patrick's torque wrench to tighten the two allen key bolts. They required more force than I had imagined. Still creaking when I was out of the saddle.

    Listening from the side of my bike Patrick reckoned the noise was coming from the front. So when we got back I torqued all the bolts on the stem and bars – some were loose – and it still creaked.

    Finally, Patrick suggested the skewer on the front wheel. Bingo! 😳

  6. Garry Lee wrote:

    Chris, I've another post describing the REAR skewer doing this!!

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