Why do cyclocross/touring bikes seem to have longer top tubes than road bikes? After using some online fit calculators, I was looking around at some bikes and frames. Surly says to pick one based on the effective top tube, for which a recommended length for me is 53.5 cm. Some shops have told me to ride a 54 cm frame, others 52 cm, mostly just based on standover height. I have been sampling some bike geometry and noticed that CX/touring bikes sometimes tend to be very long for their height:


| Bike            | Purp | Size  | Eff. TT |
|-----------------|------|-------|---------|
| Surly Straggler | CX   | 52 cm | 54.6 cm |
| Jamis Quest     | Road | 51 cm | 53.0 cm |
| Giant Defy      | Road | Small | 53.0 cm |
| Jamis Aurora    | Tour | 53 cm | 55.2 cm |
| Jamis Renegade  | Adv. | 51 cm | 53.2 cm |
| Jamis Renegade  | Adv. | 54 cm | 55.1 cm |
| Jamis Bosanova  | Tour | 51 cm | 54.0 cm |
| Jamis Bosanova  | Tour | 54 cm | 55.5 cm |
| Soma Smoothie   | Road | 52 cm | 53.0 cm |
| Soma Double-Cr. | CX   | 52 cm | 55.6 cm |
| Soma Double-Cr. | CX   | 46 cm | 53.1 cm |
| Trek Domane     | Road | 52 cm | 53.0 cm |
| Trek 720        | Adv. | 52 cm | 53.8 cm |


So, for example, if I wanted to get a Soma Double Cross, by the effective top tube recommendation, I should go for the 46 cm frame? That seems tiny. By the top tube recommendation, Surly doesn't even make a Straggler small enough, but the extra 1 cm could be handled with a smaller stem? Is there a reason the CX/touring bikes are relatively longer? Wouldn't that result in a less upright, and therefore less comfortable position for long rides?
On touring and Cyclocross bikes usually the handlebar is higher than a road bike. When the handlebar is higher the reach will be longer (like when you lift your hands they are getting further away from you body). In order to compensate on that longer distance, you can either have a longer stem or, in that case, a longer top tube.