Originally Posted by
merlinextraligh
This doesn't make sense. The chain stay length doesn't change as the frame size goes up. For example all Cervelo R3SL's have 399 mm chainstays regardless of the lenght of the top tube from 48cm to 61cm. By your theory the larger frame sizes would be horribly out of balance.
Many people who have studied bicycle dynamics at the quantitative level do indeed agree that chainstay length should increase with front center. Better designs at least compensate for rear weight bias by increasing the trail, using less fork rake on larger frames. And I can testify
personally that YES, large frames DO typically have poor handling the way most manufacturers design them. My most agile, intuitively handling bike has 47cm chainstays.
Moreover the weight distribution is going to be the same regardless of whether the reach to the bars is made up of 56cm of TT and 12cm of stem, or 58cm of TT and 10cm of stem.
I'm talking about weight distribution at the wheels not the rider contact points.. When you shorten the top tube, the front wheel moves back, hence more weight on front wheel.
What is different is that the bike with the 56 cm top tube typically has a shorter head tube, and than the bike with 58cm top tube.
Hence my point, the smaller frame tends to facilitate a more aero position, i.e. more drop from seat to bars.
Also having a short head tube doesn't explain why the bike is made with a short top tube.