The Real Reason Why New Bikes Don't Shift Properly
As Bike Cycles' Shawn Spencer demonstrated in our YouTube video, "The Most Important Part of a Bicycle Gear Adjustment and How to Do It", the main source of frustration for new bike owners is not being able to pinpoint the cause of poor gear shifting. After noodling around with barrel adjusters and limit screws, an initially simple adjustment turns into a full gear tuneup. The first step in setting up a bike's shifting is to adjust the derailleur hanger.
Just what is a derailleur hanger, you ask?
Most bikes (excluding some bikes from department or big box retail stores) that have rear shifting are equipped with a separate piece of aluminum, called a derailleur hanger, that connects the rear derailleur to the bike. This part is designed to be pliable and replaceable, as this area of the bike is routinely subjected to lateral impacts during shipping, storage, and riding.
The derailleur hanger is an inexpensive part that is adjustable given the right tool and know-how.
The Right Tool for the Job
Now if you're the DIY type then we highly recommend the hanger alignment gauge tool (HAG) by Abbey Tools. At the time of this writing the tool retails for $185. It's a worthwhile investment so long as you think you'll be performing many adjustments and have other tools, such as a bike stand, to make the work feasible.
The HAG tool is very precise and is compatible with wheels ranging from 26" to 29".