Have noticed after looking at lot of recumbents lately, there doesn't seem to be a "rhyme or reason" for chain routing on a recumbent, LOL! , single idlers, groups of 2, 3, 4, ect. We looked at a used BikeE and it had "no idler" at all, coming from the DF world, it sure looks complicated and "chain replacment" is gona put a "bite" in the wallet too! I did read on some older model "EZ-1's, that they had a semi-problem with the "chain" jumping off the small chain wheel, maybe the "over/under" helps with that??