Making a chain management idler wheel
Chain Management Idler for recumbent bikes
By Warren Beauchamp
Chain management is one of the most daunting tasks of recumbent design. How do you keep 3 times the length of a normal chain from slapping around and generally creating a nuisance? You guide it with idlers. Of course you can't buy these little gems, no that would be too easy. You have to make them. Fortunately they are pretty easy to make. You start off with the cheap in-line skate wheels that have the bearing built in (available at your local K-Mart). I jigged up the wheel in my mini-drill press, and used the bolt in the foreground to rest the cutting tool against. The cutting tool is just an old file. As seen in the picture below, I sharpened the handle end to a chisel with a bench grinder idler1.jpg (7000 bytes)
idler2.jpg (5683 bytes) The wheel is then ground down so there is about a 5/8" wide slot in the middle.
After 10 minutes or so of fending off flying rubber bits, you are left with a wheel that any recumbent enthusiast would be proud to manage their chain with. This method can just a easily be performed with a hand drill mounted in a vise. idler3.jpg (6174 bytes)

Alternatively, You could use a Fenner Drives "Powermax V belt idler". These are made of Reinforced Nylon and are relatively indestructible. They have excellent bearings pressed in. They are available in 3" and 4" from McMaster Carr, and larger sizes directly from Fenner. The 3" ones work well for return chain management, and the 4" ones are good for RWD power side management. The 6" ones are good for FWD applications. 
Fenner part numbers:
3" OD - VA3001
4" OD - VA4001
6" OD - VA6001
7.5" OD - VA7501

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