However, if speed is of primary concern, a suspended fork will impede it.
As a Social Security eligible but enthusiastic rider, speed is not my primary concern. I've been riding my old Epic (Fox Float RL100 fork) on the streets, with 100 psi slicks. The suspension makes for a very comfortable ride, and hitting curbs, etc., hasn't damaged the tires or rims - the suspension handles it. No pinch flats either. The Epic has a rear Fox Brain shock that is locked out unless one hits a curb, dropoff, etc., so it doesn't bob while climbing.
As to energy loss to the fork while climbing, it's likely miniscule. In effect the entire bike (minus front wheel & lower fork legs) is rotating around the rear axle as the fork bobs. Especially while standing, some of the pedal downstroke energy goes to fork extension, only to be fed back thru the rear axle as the fork compresses between pedal downstrokes. The rider's energy pulses are smoothed out. Energy loss is to friction within the fork, and weight, practically speaking, and I have found it to be tolerable. I climb the same hills in the same gears at the same speeds as on my steel non-suspender bike, and it seems I get just as fatigued.
I wouldn't recommend spending $2K or more for an Epic for the street! I've ridden this bike for 8+ years off-road but, like Vegas, I've limited myself to the road/bike trails. I tried it w/street slicks on the road, and was pleasantly surprised. Who'd a thought? There are some pretty nice benefits for some of us.
Last edited by melloveloyellow; 04-30-14 at 12:39 PM.