ParkingMeter

I consider frame prep analogous to blueprinting a car engine. Sure the engine will run just fine with mediocre tolerances, but mic everything and precision hone your cylinder bores and you can get substantial increases in HP and longer intervals between engine rebuilds. Same goes for bearing surfaces on a bicycle. And again, it's cheap insurance, you only do it once for the life of the frame.

Just two days ago I punched out the cups of a customer's Chris King headset. A little tight-loose pattern and a trashed lower bearing after a year of use. Guess what, head tube not faced. Probably contributed to that. Being anal-retentive, I machined it for him no charge. On a properly machined head tube I've seen those things go for several years with almost zero maintenance.

Frame prep is sort of a "specialty" service that a lot of shops I've been to (and worked for) don't offer. I've seen plenty of trashed tools too; I think a lot shops simply don't know how to do it or don't know how important it is. It's also easy to screw up your tools or the frame your prepping (use lots of cutting fluid, special fluid for aluminum, keep your taps/dies/reamers/facing mills nice and sharp, don't bang the cutters around or store them in a tool box where they'll bang around against other tools, don't turn your reamers and facers backwards when cutting). I've done some hobby-level machining, so I'm probably a little more knowledgeable about machining than the average mechanic (I am not a machinist however). When I started at the shop I'm currently at, I sent in all the cutting tools to get sharpened. The tool grinder ground off about half the lands of the BB taps to get a good edge again, they probably hadn't ever been sharpened with something like 10+ years of use! Cutting tools are unique among bicycle tools: they're expensive, very fragile and high precision. But many mechanics treat them like cone wrenches and vice grips, and they often get ruined (one shop I worked at had a Campy toolset; about a third of the tools were chipped or broken, nearly made me cry, now those are some expensive tools!).

I think what separates the good shops from the ordinary shops is service like this, where real mechanical expertise comes into play. Fixing a bike isn't a lego set or simply replacing worn parts; the best mechanics I've seen (or worked with) were masters of frame machining, alignment, overhauling hydraulic brakes and suspension, and diagnosing and fixing the puzzling repairs (e.g. mysterious noises or creaking) that other shops could not or would not do. The best ones were also the ones that could admit that they didn't or couldn't know everything there is to know about fixing bikes (bikes have gotten complicated!) at any given time.