i realise that my description of this will probably be poorly insufficient but here goes.. lately when i slow down i start hearing a tapping noise which seems to be in time with the rotation of the wheel possibly.... the slower i go, the slower the tapping. i can't tell where it comes from and it isn't that loud. i don't hear it on acceleration and only here it when slowing down.. anywhere below about 25kph. as soon as i engage the clutch the noise stops. i have rolled to a stop with clutch engaged and no noise, but normal slowing to the lights or whatever - it makes the sound every time any ideas?