For a fortnight I hear noise from my bike. The sound appears to originate somewhere aft. The bike in question is a disc brake equipped cyclo-cross bike (Merida CX600). Overall weight of bike, rider, and load is a little under 100kg. I shall describe a few observations in order to help to narrow down the cause of the noise.
- it comes from aft of the saddle
- it has a combination of pling, creak, and scratch sounds
- the sound is only audible on smooth surfaces (tarmac)
- its frequency of occurrence increases when going faster
- it does not sound the same every rotation, it is sometimes longer, shorter, sets in earlier or later
- it persists when not pedalling and with no force applied to the cranks
- it becomes louder when pedalling
- it persist when out of the saddle
- shifting my weight forward reduces the noise
- shifting my weight aft increases the noise
- there is no disc rub (sounds decidedly different) progressively pulling levers does not change sound of the noise
- spinning the wheels on a stand does not cause this noise
- turning the pedals on a stand does not cause this noise
Beside the noise the bike is new, about 800 km, in very good working order. Some observations on the bike:
- The rear brake is difficult to centre, in particular after replacing the wheel. Disc rubbing used to be common until I took a lot of time to set up the brakes.
- Something with the front fork, the through axle, hub, or bearings is not right. At side loads it may cause a clicking noise.
- I've not checked the chain for elongation in 500 km.
- Spoke tension out-of-the-box on this bike surprised me for being rather low. In particular the non-drive side of the rear wheel had and has rather soft spokes. I checked both wheels 500 km ago for centring, they were turning perfectly true.
- The bike is ridden for 40% on tarmac, 50% on smooth gravel, 10% on rough terrain (by distance).