Originally Posted by
Garilia
I'm not sure I understand enough about frame geometry to know the difference between something that is relaxed or more aggressive in terms of what to look for to narrow things down.
The best way to evaluate geometry in terms of relaxed or aggressive is to look at the head-tube angle, the wheelbase and the length of the chain-stays.
A relaxed geometry bike frame will have a smaller angle at the head-tube than a aggressive geometry bike in the same size frame. In other words, a 72 degree head tube-angle is more relaxed than a 74 degree head-tube angle, if the frame size is equivalent.
A longer wheelbase is more relaxed than a shorter wheelbase, if the frame size is equivalent.
A longer chain-stay is usually found on bike with a more relaxed geometry than the short chain-stays found on aggressive geometry bikes. A 410-420mm chain-stay is found on racing road bikes, a 425 to 435mm chain-stay is found on Cyclocross and sports touring bikes, and a 440mm or longer chain-stay is found on heavy touring bikes.
However, don't assume that the more relaxed bike geometry is automatically more comfortable than an aggressive geometry frame. An aggressive geometry bike can be made comfortable, if the bike fit is superior and if the frame compliance and wheel tire combination supports rider comfort.