Those who follow the mtb world know that there is a controversy about which is better, the standard 26" or the newer 29"wheel size. Arguments have been made for each and I'm sure each has its place. I've never ridden a 29" mtb yet so I can't comment on actual experience. I did do a comparison of sorts today though between my 26" wheel mtb with slicks and a cross bike with a wheel size equivalent to a 29".
Today's weather was even better than yesterday after the overnight rain left the area. I rode my cross bike on the exact same route I took yesterday to see how much of a difference it made. Mind you that yesterday I had two 25 minute intervals at a higher pace and today the only intensity was a series of 10 second big gear intervals. The wind for both days was about the same but some of the rail trail was a little drier today. For a 62 mile ride I was 20 minutes faster on the cross bike yet my average HR was 6 bpm lower. And after doing the intervals today early on I could feel fatigue in my legs so the last hour or so felt harder than yesterday. If I had done yesterday's workout on the cross bike I'm sure the difference would have been even higher.
The route I was on was probably 75% pavement so I figured I would be faster on the cross bike. I was surprised though that I was just as fast if not faster on the rough sections of rail trail, although certainly not as comfortable on it as on the mtb. I think I will end up using the cross bike for the Paris Ancaster race next month but I need to order some new chain rings. The mtb and big ring was a fun experiment and maybe I'll try it in a spring training road race just to see how I do.
This photo was take at the Dodge Tour de Georgia two years ago. I spent the week following the race as well as riding the roads and trails.