I wasn't seeing much difference between my 25 lb steel road bike ('89 Ironman) and sub-20 lbs carbon bike ('93 Trek 5900). The carbon bike *felt* lighter on climbs, but we don't have any long climbs. In actual practice my ride speeds/times on familiar routes I ride often are about the same.

But I suspected there was some difference due to the poor fit of the carbon bike. The early '90s Trek 5900 had a lovely, elegant, lightweight titanium stem that's ridiculously long, around 140mm. The bike was technically my size, but due to age, joint problems and injuries (neck, back and shoulder), it felt wrong.

I've tweaked the Ironman quite a bit to fit well so it feels comfortable. I figured the Trek might respond as well. So I switched to a shorter 90mm stem, compact drops with shorter reach, and planned to try again this weekend. Didn't work out, though. Felt rotten and sluggish, bailed out at 35 miles of a planned 50-60 mile ride, with only my usual average time. The bike felt better with the new stem and bar. I just didn't have the energy to make good use of it. So I'll try again next weekend.

It's difficult to judge my performance from Strava unless I crop the beginning and end of a ride. I need 30 minutes just to warm up and another 15-30 to cool down, finishing very slowly around 10-12 mph. I don't usually crop my rides but I do select the middle 20-30 miles to compare with previous efforts, via private segments that are interesting only to me. My average speed has increased during my maximum effort segments of 10 to 20 or more miles. But I still don't see significant differences between the two bikes, despite the 5 lb weight difference.

Gearing is different too. I've been experimenting with the old Shimano Biopace on the Trek and I'm not convinced there's any advantage. There's no disadvantage either. But it feels odd, kinda grindy. I'm a spinner and I suspect non-circular chainrings, or at least the Biopace, may be better suited to a lower cadence. So the two bikes aren't really comparable, with only weight as the main difference.