I am interested in the purchase of a new bike. I want to buy a Surly Long Haul Trucker. I have had bikes that did not fit me well and I do not want to make a fitting mistake.

So, I am asking advice on the process I should use to assure a good fit at the end of the day.

1) I and my local bike shop determine the general size that I need.

2) Once that is determined, then the fit can be tweaked to my body using stems, proper seat placement and handle bar positioning.

Is this the general process most use to get a good fit?

they should measure you for sizing and then put you on a trainer to make sure it is all tweeked the way "it should be"

then you will end up making little adjustments as you ride...

Long Haul Trucker is a nice bike!

Are buying it from the LBS? Do they seem to take a real interest in fitting you to the bike?

Some bike shops are better than others when it comes to fit. It may be advisable to educate yourself so your BSometer is calibrated when listening to the shops advice.I would recommend Lennard Zinn's advice on bike fit in "Zinn and the Art of Road Bike Maintenance" or there may be some threads of interest in his tech column at VeloNews.com.

But yeah, you have the basics. Some bike shops are really good at swapping handlebars, stems and crank lengths to help tweak the fit. Others charge for it. Be nice to know how they do it up front.

You seem to have the general idea. I agree that you should be careful about buying into a lot of the BS that surrounds bike fitting. I've had good experience with two fitters here, both of whom fitted the old fashioned way--watching me pedal in the trainer, with no "systems" or body scans.

From that experience, I learned that even though two of my bikes are different "sizes", (one a 56 and the other a 58) they both have the same top tube measurement, within a quarter-inch. And for me, it's the top tube measurement, not the seat tube (which is usually the one used to determine frame size) that makes the difference.

Recently, I purchased another bike, used. I bought it from the LBS who sold me my first bike, which was a size too small. He told me this bike was a size too big. I measured the top tube. It was spot on. A test ride confirmed it--fit like a glove, so I bought it. On my first 20-mile ride on it, it felt like old home week.

There are two morals here: 1) That this particular dealer tends to undersize, and 2) I should always carry a tape measure when I buy a bike. A 22" to 22½" top tube (or in the case of sloping, the "virtual" top tube) is what fits me.

Do your own measurements of bikes you have that fit, and those that do not. Bring that information with you, and start from there.

EDIT: The other measurement that's important for me is crank length. 170mm feels like I'm taking baby steps, or the pedaling equivalent of pulling punches. 175mm fits just fine--it feels like I'm using my whole leg. So any bike with 175mm cranks and a 22-22½" top tube is going to be right for me, with only minor saddle and bar tweaking.

This question is much like the saddle debate. I think everyone feels strongly one way or other about how a bike should fit. The LHT is very much a copy of old school bikes like the Rivendel Atlantis and some other custom built touring type bikes. So i think its good to search out what builders of those bikes say. Having said that perhaps you should read up on what Grant Peterson of Rivendel Bikes has to say. It worked for me and i just recently purchased a LHT.
My LBS is quite experienced and i take his suggestions seriously,but he was somewhat wrong on my fit for LHT, he would have had me on a 58. He felt my arms werent bent enough on size(60) that i was comfortable on,what he didnt know was that i just dont bend my arms much at all, so if i went a size smaller that he suggested id still not bend my arms much so id just sit up more. I said all that to say that you have to ride what works for you, and dont completely rely on anyones formula. I can ride 58 LHT or 60 LHT. The 60 worked for me best. Im 6ft with 35" inseam. I tend to like large frames with only about a fistful of seat post sticking out,which gets my bars up where i like them. Bigger the frame the higher the bars are in relation to saddle on these style of bikes. I did adjust the bars, tilted up a bit and moved the brakes up a bit on bars as well,making the hoods just a bit more comfy. Didnt need shorter stem. Most dealers will help with shorter stems or whatever so you are comfy, sometimes minor changes like i did makes all the difference.take your time ride several sizes if you can. Best of luck.