Exquisite Idler Kits by TerraCycle

Posted on 28th December 2007 in Technical Tips


Idlers are the bread and butter of TerraCycle- it is the most of what we do and what we think about day in and day out. We spend hours on the phone every week with customers looking for more out of their bikes, and we are successful at getting them that benefit. Years have been spent developing the TerraCycle idlers, and without tooting our own horn, we probably know more about idlers and chain lines for recumbents than anyone in the business. Years of experience talking to riders, plus our own experiences with everything from streamliners to touring bikes, has taught us a lot about what makes recumbent chainlines work better. TerraCycle idlers have been recognized as the finest available. Each idler is made here in Portland, Oregon in our own machine shop with complete dedication to detail and quality.

CNC machined idlers with tight tolerances deliver more power to your drive train and are quieter, smoother, and allow the chainline to run with less vibration. The drive train is one place on a bike that deserves the best parts you can afford. Because of the long lengths of chain that recumbents have, a quality idler system is really key. The industry standard has been to use inexpensive molded plastic rollers that are highly inefficient at transferring chain power to the rear wheel. Bumping chain along a hard non-toothed surface on the power side makes no sense at all. Everywhere else in the power side of your drive train (chainrings and cassette) toothed cogs are used- why should the idler be any less important? Running a loaded chain over a non-cogged surface causes friction and power loss as the chain attempts to dig itself a groove in the plastic idler, or worse yet, with harder plastic idlers, the chain bumps its way along on the way to the rear or drive wheel. A chain has a very specific shape that is designed to run on only one thing when loaded- and that is a cog. Don’t let anyone tell you anything different because any good engineer will tell you that simply isn’t the case. The shape of the molded non-cogged power idler is probably better designed for lines on a boat. Unfortunately our bikes aren’t run with ropes, we have chains, so what we run that chain over shouldn’t look like something designed for rope.

There is an exception to the cog rule and that is for the return chain which is only loaded by its own weight plus the tension from the derailleur arm spring. In this application a non-cogged idler is an option if it is well made/has high quality bearings and is not prone to premature wear. Our return idlers use the same industrial urethane material in the beds as is found on the most expensive warehouse rollers. Because the return chain tends to wander side to side within the idler without the higher loads our floating return system allow the change in chain angle to be accomodated as you change gears. To illustrate the issues with molded power idlers for longevity we recently received a call from a customer on a cross country trip who called us from a remote location in Indiana telling us that his stock idler system had completely disintegrated rendering his bike un-rideable. Many customers report that their stock idlers are wearing out in a matter of a few months. Our belief is that drive train components should be much longer lived and more efficient than this, which is why we design our idlers to last the life of your bike.

Some manufacturers are using softer plastics in an attempt to fool you into thinking that the idler is working better because it sounds quieter than the harder plastics, but again don’t be fooled, you aren’t gaining anything and maybe even losing even more power than you imagine. Lower noise does not automatically equate to efficiency. While we are on the friction topic, chain tubes cause friction on a chain. No matter how nice the tube is (and there is a wide range of tube qualities out there) you are still running a chain on or through a surface it isn’t optimally designed for. Chain tubes wear out and it really isn’t smart to run a chain though a variety of angles between your crank and your rear wheel through lots of tubing. However, if the goal is to keep your pant leg free from chain grease on a commuter bike, then by all means the trade off in efficiency is probably worth it. The number of customers who call asking us to help them get rid of the multiple feet of tubing their bikes came with is phenomenal. We use chain tubes on a very few of our kits, basically where the bike and the chainline absolutely require it. We use high quality, low noise/low friction tube, keep the lengths short, and flare BOTH ends of the tube to reduce entry/exit vibration. If you think about the thousands of pedal strokes you do annually, and then think about power robbing idlers, or multiple/long lengths of chain tubing, it makes no sense at all!We know performance riders who brag about the latest wheel set or special crank as they attempt to squeeze a little more speed or a few more miles out of their rides with the same amount of watts into the pedals, but then we see plastic idlers on those bikes and think- Wow! There’s some energy being wasted that could be turned into power!

Lots of companies brag about their involvement in racing, and to add our note to this, TerraCycle sponsors several teams, including the very successful RAO Speedwagon Recumbent Race Team which has for the last two years won the recumbent division, plus a first and second overall in “Race Across Oregon” which is known as the hardest pre-RAAM qualifier in the nation (539 miles / 45,000 plus feet of climbing / Non-Stop). Each of the team bikes, from Streamliner to High Racer, have TerraCycle Idlers on them, because the team knows that when you are racing on a course that challenging you can’t afford anything but the best in your drive train to ensure no amount of energy is wasted. We pushed the team riders to their limits riding so many miles very fast with so much climbing and very little rest. This kind of performance demands that you gain those critical minutes for every hour of pedalling, because in the end the winning margin can end up being very small. TerraCycle has for multiple years now supplied idlers to teams competing in the ASME races. The engineering students build a variety of HPV’s and need efficient and powerful chain management to get the most out of their vehicles in this very demanding competition. We pride ourselves on helping the engineering students with our state of the art idlers in a variety of configurations to meet their needs.

TerraCycle idlers initially cost more, but if you factor in the longevity, and the fact that they are not prone to failure, plus the pedaling efficiency you will gain, then they really are a great value. All TerraCycle idlers utilize industry grade ABEC-7 bearings- which are replaceable- as well as industrial grade urethane beds on the return side. Idler plates are machined aluminum and high grade polycarbonate. All fasteners are stainless steel. Idler cogs are 6Al/4V Titanium or 7075 Aluminum. Each idler is fully rebuildable if that ever becomes necessary (so far we have only had to do two of these in five years and both of these were due to damage caused by accidents). All Terracycle idlers are fully warrantied for five years. No other manufacturer comes close to that kind of guarantee. The diameter of our standard 15T idlers is 2.75 inches or 70mm and use 8mm bearings. We now offer 13T(2.4in/61mm OD), 14T(2.5in/65mm OD), and 23T(4.0in/101mm OD) idlers as well, for special bikes/trikes (velomobiles, FWD setups, etc.). We have idler replacement kits for most brands of recumbents and experimenter kits for homebuilders or those bikes not listed.

We are always working on new designs for bikes that we do not presently cover, so check back regularly to get updates on what is new in our product line. When deciding between a Titanium or an Aluminum cog, we advise that stronger riders or any rider doing high mileage go with Titanium. The Aluminum cogs will give a long useful service life but will show more wear after thousands of miles. We generally recommend a titanium cog for trikes since the angle of the chain line tends to be larger putting more stress on the idler.

Please call us to discuss any of the above if you need more information or want to discuss the specifics of your bike. We are always willing to spend the time to ensure you feel confident about making a good decision that has real benefit for your riding.

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