Idler? I Thought My Bike Was A Mover!
Idlers 101: Power, Return and Over/Under
Chain that moves from back to front and does all the work is the power portion of chain. It's the line of chain on top and it carries the load (all that muscular power that you're putting into each push of the pedal). This is where a Power Idler goes. In the old days, recumbent manufacturers used skateboard wheels for idlers, but because you're pushing so powerfully, the chain would wear down the polyurethane with unnecessary friction. Today, thanks to a guy named Pat Franz, we put a toothed cog in our power idlers. The teeth keep your chain from wandering and, because the line is so taut, the chain spins the idler without any undue friction or slowing.
The other half of the chain, the part that runs below the power, is the return. It's the bottom and just kinda hangs out. Its job is to return back to the chainring. On this section of chain is where you find the (you guessed it) Return Idler. We don't leave out the toothed cog in the return idler just because it's extraneous; we do so because a lightly loaded chain (the return side) can skip over the teeth of the cog, causing noise and friction and possibly damage to your chain.
Both instances (power and return) occur on any given chain, but, depending on the cycle, the chain can follow different paths and require different sets of idlers. For bikes whose power-side and return-side chain spin the idler in the same direction and run close together, an Over/Under Idler is perfect. The over/under is a two-in-one idler, serving both the power and return chain.
Idlers 201: Sport vs. Elite
Originally designed as a cost-saver to help first timers (or those with multiple bikes) to upgrade to T-Cycle quality, the T-Cycle Sport Series Power Side Idler, Return Side Idler or Over/Under Idler will be the best (and only) idlers many riders ever need. Sport Series Idlers are designed for supreme function and durability. Made with a precisely crafted 7075 aluminum cog for the power side and an industrial urethane band on the return, with military-grade ballistic nylon side plates and with top quality ABEC 7 steel bearings, the Sport Series Idlers are built to last and do an exceptional job maintaining your chainline.
Upgrading to Elite Series Idlers gives a slight boost in performance, further improvements to durability, and an MTV-worthy makeover in looks. When you upgrade, you find that what was an all steel ABEC 7 bearing is now a smoother and more durable hybrid ceramic ball bearing; what were ballistic nylon are now two immaculately machined aluminum side plates whose beauty is only surpassed by their fortitude; and what was precision aluminum is now an indestructible titanium cog born of meticulous and unrelenting fidelity to the the ideals of the perfect idler. In short: the Elite Series Idlers are the undisputed best idlers in the world in functionality, durability and serious bling-factor.
Ceramic vs. Hybrid Bearings
Short answer: because better bearings—like those found in T-Cycle idlers—drastically increase the lifetime of your product. One customer has ridden for 50,000mi in the rain and mud of Oregon without his T-Cycle idler giving way!
The Annular Bearing Engineering Committee (ABEC) is a group that formed within the American Bearing Manufacturers Association in order to create an industry standard for the tolerances of ball bearings. On the ABEC scale a higher number means a more precise bearing. There are five grades: 1, 3, 5, 7, and 9. All T-Cycle idlers come with high quality ABEC 7 bearings, with the exception of Elite idlers, which can be upgraded to hybrid ceramic bearings.
In a hybrid ceramic bearing, ceramic balls are encased in the same steel rings as a standard bearing. The ceramic balls, however, are stronger and more friction resistant than steel, giving the bearing a smoother and longer-lasting ride. Since the ball is what wears out when the bearings are used on cycles, the hybrid ceramic is a good match.
For those of you looking to impress your friends with intricate technical facts of bearings and the ABEC rating system, here's a link to AST Bearings Inc.'s explanation of bearing precision.