I like the internal routing on my kestrel. the housings are not used inside. the only issue I had was I had no way of telling if my deraileur cables were crossed inside my down tube. I still dont know for sure but I pulled one out and while the other one was tightened I fed it back in. I feel pretty confident they are correct.
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2010 Kestrel RT900SL, 800k carbon, chorus/record, speedplay, zonda
2000 litespeed Unicoi Ti, XTR,XT, Campy crank, time atac, carbon forks