Gloom and doom aside, go for it! If you like what you do, have the expertise, and like helping others; you can call the shots. Renumeration will require some business knowledge and an accountant. You might find a small business class at a community college and an accountant can help tremendously. Liability insurance comes in many levels and cost as well as tax credits for overhead including dedicated space in a home. I've known a few folks over the years, and my wife, who have had their own business. It's work up front, but once you've got system it's not that bad. One thing I learned from a 1 man auto service is to have a bank account for the shop. It's very easy to foul up for taxes with a personal or joint account to run a shop from.
Liability depends on how to protect yourself. For used sales, do what car guys do, "sold as is no warranty expressed or implied". You can state what you've checked or repaired, but the buyer assumes all risk.
If a suit does rear it's head, it's up to the plaintiff to prove and a judge to decide if there was fraud, criminal intent, willful negligence, disregard for proper accepted methods of repair or procedure. If your experience is deep, and you care about a reputation; I doubt any questionable bike or frame will leave your shop.
The shops that have worked on our family vehicles, (for which I didn't have time or tools) were always good in that they communicated with us. Unexpected costs, delays in parts, maybe a wrong diagnosis or deeper root cause were always explained before the money was spent. That and good workmanship kept us using them for many years.
Good Luck and Good Fortune!
Last edited by Greg R; 10-20-21 at 08:52 PM.