i'm 5.8 i've been using a 49" size compact frame for a few months,its a pretty heavy bike so i treated myself to a second hand cannondale system six, 105 groupset. frame size 54" traditional which is what the bike shop recommended for my height . the bike is slightly lighter than my last frame. however i've been doing the same 10 mile route for the last few weeks and my times are down by a minute. I expected my times to improve not get worse.
i think the setup is right,same tyres, the seatpost is not quite as high as it was on the smaller frame but the distance from the seat to the bottom bracket is the same. any ideas? i might just be i'm off form lately
Frame size IS the big difference. The right frame means everything. 54 might be about right, might be too big. Height alone is not the only factor. As far as why you are slower, could be any number of non-bike factors. Bikes don't go faster, people do.
frame size matters for comfort. If you feel streched out, the top tube is too long, and go down a size in frames, and just increase seat height. You can also alter reach via stem adjustment, but that should be for fine tuning. Usually when sizing someone for a frame, i take the height as the baseline for frame height, and then see how the reach looks to the hoods. if it's just off by a few mm/cm, a stem shorter/longer stem can usually do the trick.
In terms of why you're a minute slower, stop slacking off while riding. The bike wont make that huge a difference, especially if you're not experiancing discomfort.
