Knocking noise from back wheel?

[nmfeb70]

Hi All,
I'm new here and would like to throw this one out there. I ride a GT Aggressor Sport 2019 MTB which recently needed a new bottom bracket. There may be no connection but since the replacement I've had an intermittent non-metallic knocking sound which seems to be coming from the back wheel? It happens when I pedal in a higher gear ie. the 6th and 7th rear cogs and the middle and higher front chain wheel. I removed all the accessories (mudguards, rear light, tool kit) but the knocking persisted. The rear wheel cassette is not loose and I have adjusted the limiting screws on the front derailleur so they are not touching the chain. This is infuriating as it can happen at the start, middle or end of my ride. Any similar experiences or explanations? Many Thanks.

 

[fossyant]

I'd suggest the bottom bracket (square taper) isn't tight enough - I.e. the lock ring, or even drive side isn't quite tight enough.

 

[Paulus]

I would suggest that you check the rear wheel bearings as well. I have had on an occasion on MrsP's bike a clonking sound from down there, and after greasing and adjusting the hub bearings it miraculously disappeared.

 

[Globalti]

Yes remove the rear wheel and spin it while holding the axle and feeling for dry, loose or rough bearings.

 

[nmfeb70]

Thanks All, I went out for a long ride earlier and the bike misbehaved all the way. I took it back the shop where I bought it three months ago and following a number of checks to eliminate everything it came down to the rear freewheel. They replaced the freewheel and so far it sounds quiet. I'm crossing my fingers and hope that's the end of the annoying knock...knock..knock! Thanks.