Maintenance advise for the Rookie...

[Elvin]

I recently bought myself my first road bicycle.

 

How do you know when the tires need replacing? the tires are smooth when still new, so one cant judge by looking at the thread of the tire ???

And also how do you get your chain and the gears clean from the old black grease and stuff, is there a certain product on the market? Or will a brush and soupy water do the job ?

thanks!