For the past 20-odd years, I've gone on the Top-Tube length, in order to get a better postion
I still end up with the saddle all the way back on the rails, & a '100mm', or '120mm' stem
5'9", but with fairly long Femurs
- '100' on the work bike
That's due to more clothes in winter, so less flexible - even so, the headtube is an inch shorter/lower than my newest road-bike
- '120' on three of my road-bikes (the CX though, has a 100', for a slightly more upright position - it was bought as a race bike)