starjet905

Apologies if this is the wrong place to ask but here goes

Recently I bought a new bike, but it's a very cheap local thing

Anyway, the issue is, anytime there's some impact on the front wheel (eg: going over a speed bump, falling into a pothole), there's a distinct metallic ping sound ringing out
It does not occur when I'm riding on a smooth flat road

At home I can recreate this by lifting the front of the bike with the handlebars and then hitting the ground with the wheel
I have tried with both the suspension locked and open, and it happens similarly
However, if I hold down the front brake when I do it, then I don't hear the sound
So it's making me think that perhaps the rotor is hitting the brake caliper when the wheel is hit

However, I don't know how to fix this
I have checked to see if there's any play in the wheel, and there isn't anything that I can notice
I have checked and re-tightened the QR skewer, but the problem continues
Checked if the brake caliper was loose but that doesn't seem to be the case either, and the brake works just fine

Any thoughts about how I could proceed with this?
I can of course ignore the sound, but I don't know if there's any safety concern here

PS. I'm new to disc brakes. All my life I've ridden bikes with rim brakes so this is a bit of a new "adventure" for me

CAT7RDR

Use a bright light and magnifier and examine your rim especially around the nipples.
Sometimes cracks form and IME you'll hear pinging sounds.

BlazingPedals

I'd be suspicious of the spokes not being relieved properly. That'll result in the wheel losing its trueness over time.

Desert Ryder

My first inclination would be spokes.

starjet905

Thanks for the quick responses, people

I have checked to see if any spokes are loose but at least from my amateur point of view, I can't seem to find anything off
But particularly with the potential cracks, I'm not quite confident my checkup was sufficient

On the other hand, if I flick the front rotor with my fingernail, the resulting ping is very similar to what I hear
This combined with the fact that holding the front brake stops the noise makes me strongly suspect the brake

However I am nowhere near experienced as you people, so it's very likely that I could be wrong

Is there some way for me to find out for sure where the noise is originating by myself? I'd rather not take this back to the shop, as I would lose it for a good long period while they work through their existing stuff and finally get to mine

EDIT: Also if it matters, I've ridden this bike a little bit at this point, roughly 50km
Would spokes not being relieved properly still be causing pings at this point?

alcjphil

I would check the bolts holding the disc rotor in place

BlazingPedals

Yes! Especially if these are mechanical brakes which deflect the rotor toward the wheel (and away from a bolt which may be sticking too far through the dropout.)

rsbob 

I had one set of carbon wheels where every time I hit a good sized bump or pothole and experienced the same ‘ting ting ting” which would drive me crazy. Had the wheels looked at, and got a new front disc, but with the next hit, back we went to the ‘tings’. Think it was just that the wheel was susceptible to being deformed. Got some new carbons of a different manufacture and the only time they ting is when the disc overheats on fast steep descents and they expand. When they cool, the noise disappears.

I surmise your wheels have the same susceptibility. The good news is that after enough miles the sound would stop, but then with the next hit, back it would be for many miles. If it is driving you nuts, I am neurotic about noises, you may want to find a different front wheel. I went with Hunt and haven’t had any issues.

starjet905

Thanks again, people
Checked the bolts, and they do seem fine
The wheel potentially deforming is a possibility, though mine are just basic aluminium alloy rims, not carbon

Iride01 

Might be nothing to be concerned about. Just keep an eye and ear on it and if it is a issue it will eventually show itself to you. Not being oblivious to things changing will keep it from being a threat to your safety.