One of the undeniable advantages of transportation cycling is the relative economy of maintenance.
Parts are simple and relatively inexpensive. Problems are usually pretty easy to diagnose, and with a minimum of training and tools, the shade-tree bike mechanic can do most of his own wrenching. (About the only component I haven't replaced yet is a headset. And I've disassembled and cleaned and lubed a headset.)
I must confess... in the past, I've generally taken that "maintenance economy" to the extreme. Rather than practicing some "preventive maintenance," in many cases I've just gone 'til something broke, then replaced it.
With my "new" (as of last November) bicycle, I've tried to be more proactive. Once a month, I've given the drivetrain a pretty thorough scrubbing, using degreaser and a brush to knock the gunk back. (Figure it costs maybe 2 bucks and 20 minutes per session... it's not like my maintenance expenses have risen dramatically.) And I've also tried to replace or adjust stuff when symptoms first started displaying, rather than waiting 'til I was grounded until I took action.
And it has paid off. My riding experience has been more pleasant and more stress-free.
And in the long run, my new proactive approach may be more economical.
The new bike has "10 speed" drivetrain componentry.
Don't say, "Big deal! My Schwinn Varsity was a ten speed!"
The "new" ten speed is ten on the back, and two or three on the front! (I've got 30 flippin' gear ratios! Frankly, I'd be delighted with half that many, if they covered the same range.)
The ten speed cassettes and chains are correspondingly more pricey than the nine speed, and eight speed, and seven speed...
I'm still on my original cassette and chain, and I expect they'll last for at least a year. I hope they last 'til next spring; I'd hate to change out that stuff going into the bad-weather months.
I'm spoiled! If I spend $100 or $150 a year on bicycle maintenance, it makes me start sweatin'. But compare that with the cost of maintaining an automobile, to keep it providing reliable transportation. Ouch! (The wife's minivan needs a new catalytic converter - $825.10!)