Originally Posted by
kaliayev
This is not necessarily correct. A lot of the newer performance oriented hybrids such as the Trek FX series are basically road bikes with flat bars. Many of the first hybrids also had road geometries. Take a look at the pic of the Trek 750 I posted. It has the same geometry of the Trek 520 with a mere 1cm difference in the chain length.
The post I was referring to stated that the effective top tube length is
often different which is very true and poses the problem I stated. Even if the bike has a road geometry, drops and straight bars put your hands in different places. Without changing the stem length, drop bars aren't going to be comfortable unless the bike didn't fit in the first place and you just get lucky.
Though getting a different stem isn't necessarily a big deal, it's possible that you'd never be able to get the fit right when you switch to drops even if the bike has a road geometry. Just something to consider. I'm not against conversions. I've done my own but it can get tricky and often isn't worth it in the end.
Here's maybe a simpler way to state the same thing. Just because a manufacturer sells both drop bar and straight bar bikes using the same frame doesn't mean the same size frame will work for a given rider for both models. A 56 cm might fit great on the straight bar version but stretch the rider out too much on the drop bar version.