Flex vs sectional track
This article applies to every scale, but was originally written with Garden ("G" scale or #1 gauge track).
Flex track (aka flextrack) is bendable track that is designed to be shaped into any desired radius. "G" scale or #1 gauge track may be called flex track, but must be bent with a railbender. The alternative to flex track is sectional track which is pre-made track in sections in various lengths and turn radius's (how sharp the curve would be).
Despite the name, stainless steel flex track is very durable and shouldn't simply be bent by just pushing on the rail or "belly bending". Code 332 track is substantial enough to require a special tool called a rail bender to bend the flex track. You should always use a rail bender to ensure smooth, controlled bends and to ensure the top and bottom portions of the rail bend together without causing the rails to twist.
Flex track vs sectional track
It's been asked on nearly every forum on the intertubes: Flex or sectional? Most responses are for flex, and here is why.
This blog post will break down why flex track is generally more cost effective, easier to use than sectional, and provides the ability to easily make layouts more prototypical without extra effort or much thought. Flex track also allows you to place the track in your planned right of way with less frustration, prolong long rolling stock, better electrical conductivity, less derailments, and is usually more attractive than sectional.
Flex track allows you to be creative and come up with virtually any layout you can think of with unlimited radius selections. No longer are you required to stay within the bounds of various sectional piece radius's or adapt a layout to fit within the limits of a sectional track. Also, who hasn't used the wrong radius turn to complete "the last mile" of track so you can just run your trains instead of buying another section of track. With flex, you just take a rail and bend it how you want it.
Along with creating your unique layout, you can also easily implement more realistic layouts without any additional effort; such as creating easements going into and out of curves. Although this may be done for a more prototypical appearance, it also prevents the your rolling stock from lurching into turns like a toy which places additional stresses on the wheels and trucks of your rolling stock. This results in additional wear and tear - ultimately more maintenance for you!. Flex track allows you to gently increase the turn (decrease the radius) and provides more realistic operation which translates to less wear and tear on your rolling stock.
Using longer pieces of flex track versus shorter pieces of track means less joints. Each joint is a potential for mis-alignment which leads to derailment and a chance for electric continuity issues. Using a quality rail clamp does mitigate these, but not eliminate them. Using the longest flex track that you can find means less track joiners for electrical loss as well as less chance for derailments. Using flex track allows you to avoid placing the track joints in critical areas, such as grade changes or the steepest part of a curve - place the joint just before the turn. Try to buy the longest sections of track possible.
Another great benefit is that you can actually buy less track (read: more rolling stock instead of track sitting in storage). No longer do you need keep a wide array of track in personal your stash in various radius sizes. Whether your building your first layout, adding on a section, or modifying your track - you only have to stock one item as you can simply bend it into whatever you need.
Quality track can be re-bent many times before showing signs of wear. Go ahead, lay it down, and if you don't like, bend it again.
Ease of install
Are you new to laying track? Flex track is actually easier to do than sectional track if you are using longer rail lengths - you have less pieces to deal with. Bending track is a topic of it's own, but in short here are two quick methods to lay flex track: 1. You can lay out your track and use a rail bender on site. Simply lay the track down and use a dual rail bender to bend both rails simultaneously on your layout and form as needed. 2. You can roughly measure where you want the track to be and roughly bend your track elsewhere before bringing it to your layout to make the final adjustments for the perfect fit. No matter the layout, you'll want to cut the track, regardless if you're using sectional or flex track so this aspect is a wash no matter how you look at it...unless you decide to only make simple temporary holiday layouts.