I wouldn't call 4.6 fast. It's all relative. The chart is grossly mislabeled. It's a nice litttle laugh, but not useful at all for actual analysis. For example, i would probably suck in a p/1 field with a measly 5.1 w/kg ftp (heck even at my 5.4 w/kg peak back when i was 145 and getting ready for nationals). Now if we were doing 5 minute climbs i would be set, or 1 minute, or 3 minute, or anything less than 10 minutes where my real power is, but true 20 minute to hour climbs suck penis butt, especially in a p/1/2 field.

Anyway back to the important part. the op is just new and doesn't have a ton of raw power. Sitting in at 25 is pretty easy (even pulling isnt that hard). Also he is probably pushing too hard too early. Most rides start this way: slow people pushing the pace early, faster riders going faster later on. Also it's very easy to gain speed on the flats. For example today i averaged 240 watts and only did 31 km/h, but if i had sat in the drops, or gone on a flatter route, i could have been much higher (maybe 34-36 km/hr). It's just like when i do hour long sst sessions at 24 mph at 330 watts. I'm sitting upright on the hoods. Get me on my tt bike for the same session i'll be doing low 27s. Give me a threshold effort on the tt bike, i'm all of a sudden at 28-29 mph with all my goofy aero stuff.