Cipollini

last week, i did a 37km ride on my xc bike using fat tires(both 2.1") and arrived at the finish line at 1 hour 35 minutes. So, last 2 days ago, i was riding this same course again but this time, on roadbike. I just cant believed that i clocked almost the same time as i was on xc bike. At first, i thought it was the headwind. But after i recalled few times, the wind direction is almost the same on both situation.

There are few possibilities in my mind now. The drivetrain. Maybe my(5 foot 11 inch/56kg) leg are too weak to pedal the 39/53t chainring with 13-25t cassette compared to my xc bike setting which is using 22/32/44 with 11-34t on the rear. As far as i can remember, im using 44t(xc bike) all the time during the ride while i was on 39t most of the time with my roadbike except some descents. The only differences are the rear cogs. Sometimes i switch between 2nd to 5th largest cog on my xc. Honestly, i was struggled to maintain the smooth cadence on my roadbike (using mostly 2nd larged to 6th largest cog).
Another possibilities should be the bike settings..

Well, instead of complaining the drivetrain, maybe i can do something to my legs. Is there any other ways to improve my leg's strength? Im worried to do strength training because my right knee got injured few months ago.

silversmith

I seem to vary a lot even when I use the same bike.

urbanknight

Does this route include any stop lights, signs, or traffic?

johnny99

If you're struggling to maintain a smooth cadence on your road bike, it may not fit you properly. Or maybe you just need to get used to the riding position.

Gearing shouldn't be an issue unless you find yourself in the fastest or in the slowest gear too much. In the middle gears, the road bike should be superior because of the closer gear spacing.

2manybikes

Do you know that you can't feel a tailwind?

Cipollini

eemm..nope. the route is quite on the country side. In fact, there arent much vehicles using that route..

Im thinking of investing in compact crank. Or do more strength training on leg.

DannoXYZ 

I'd say to take it easy and not worry about speed right now. Spin easy gears and get your smooth cadence at high-RPMs down. Jerky motions will easily tear apart your knee. And strength training will help you avoid injuries to your knees. If you work up to high-strenght/heavy-weights in the gym, there's no way you can stress your knees that much on the bike.