Mate Mate Maaaaate...
I did a bike maintenance course a while back (when my MTB was new), but we didn't cover remote web diagnosis...

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Anyway the noise you hearing, when does it occur? When you push down on the pedals? If so could be a number of things, one of which was covered by Mike in that the front brake pads are touching the disk.
If your bike has very cheap front suspension (i.e. it's an el-cheapo MTB), there's a good chance that the forks are flexing (or one leg is compressing while the other isn't) as you put pressure on the pedals and they are going slightly out of kilter and touching each side of the rim as you pedal. Yoy can get rid of this by buying a fork brace for $20-30. Other problems could be the bearings in the bottom bracket not being lubricated, the cranks being loose or the pedals crap. If the noise if definitely coming from the front the front wheel bearings could be dry (and probably now stuffed

). The are generally loose ball bearings, not sealed units like a motorbike's...
Just for interest's sake, how much does the bike weigh? Most people that buy bikes at the cheap end of the scale don't end up riding them for very long as they rapidly get pissed off pushing the weight around, so you did well riding the 17km

. The other thing that happens is that you end up using all these muscles that you haven't ever used in your backside and thighs, and you may have trouble walking tomorrow. That's ok though, the soreness will pass in about a week. Don't be tempted to buy a soft comfy seat though, they are the worst on the arse. You need one that supports the bones in your backside, rather than a pillow.
BTW, $160 is extremely cheap for a pushie

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