My LBS guys work with me on stuff. I bought a Surly Cross Check on Ebay. I got a good price. I brought it to them to work on. They oo'd and ahh'd over the bike, and I spent over $100 getting it "just right." I also get them to order parts for me that I could just as easily order myself for the relationship. They work on my Bike Friday - it didn't come from them.

If they aren't a dealer in that kind of bike, they'll probably be cool with it. Just explain and communicate. The bad service sucks - mine will re-fix any minor problem, but honestly the wrench who does much of my work is so good it's never an issue......

RM - there may be liability issues with installing an unknown part. Another good reason....