I have a Dawes Wotoga Moutain Bike. When I am going up a hill and 'pushing hard', whatever gear I am in, I get a knocking noise coming through the pedals. This doesn't happen when I am riding normally. The bike and pedals etc are oiled. I look forward to the responses.
Listen to the knocking sound and try and see if the frequency relates to something on your bike. If it seems to occur about once every pedal cycle, irrespective of what gear you are in, it is likely to be either the pedals or the bottom bracket. I had a similar problem with my bike, which I bought from Evans. I took it to the LBS and it turned out they hadn't fitted the bottom bracket properly, it wasn't completely threaded on. LBS charged me £10 for inspection and tightening it, which I then charged to Evans...
Normally if your chain/rear cassette is worn/knackered/loose etc. you will find when putting more effort through the pedals that the gear may slip and you get an annoying crunch followed by a slipping sensation as the chain moves between gears (on the rear cassette). Once it has moved, it may stay in the new position, but more often than not will jump back and the process will start again.
Could you describe the sound any better and any 'feeling' that goes with it. Bottom bracket gives you a graunchy/grating noise at a particular position in the pedal stroke and normally is worse under power. You can feel it through the pedals.
The problem I describe above is more of a load metallic banging as the chain slips, accompanied with some slippage.
