Before we start delving into historical and contemporary examples and minutae such as specific component spec, it is worth making an initial attempt to quantify the defining characteristics of a well designed cycle sportive bicycle. Off the top of my head, I think that a good sportive bike will be charactereized by at least seven definsing characterstics-
Performance Geometry and Componentry:
In the past sportive bicyles often did double duty as racing bikes. You can make an argument that more specialized bicycles are optimum for road racing today, but a sportive bike should be a performance machine. Within the limitations imposed by the need to be an all-rounder, the bicycle should be light and should have geometry optimized for performance. You want your everyday bike to be fun to ride. You also want it to get you farther, faster, and easier and to be confidence inspiring in situations that require good handling. The bike needs to be at home on a fast club ride. In my opinion it is the optimum machine for maximizing your speed on rides around the century to double-century range and its design and component choices needs to reflect that.
A good sportive bike should eat up chipseal and other bad road conditions. This means that it needs to be designed to handle a bigger tire. Something in 28mm range with fenders is a minimum.
A good sportive bike should have double fender eylets front and rear. This helps with solid installation that will keep your fenders in place and minimize any rattles or vibrations. It also helps get a good fender line that follows the profile of the tire.
The bike needs to have brakes that will work with the larger tire and fenders. This can mean long reach side-pulls, cantilevers, or center-pulls. My personal inclination is towards the latter, but good results are possible with all three types as long as they are integrated well into the overall frame design.
The frame and the components need to be able to stand up to regular use over decades. This doesn’t mean the bike should be a tank (in fact it should be as light as possible), but it shouldn’t be designed like a single-season race bike. Unlike many expensive carbon machines it needs to be crashable.
To date, the vast majority of high-quality cycle sportive bikes have been made from steel tubing. There are some true sportive bikes out there in titanium and I am open to the concept of a carbon sportive bike, although brittleness and difficulty of repair are strong marks against carbon. There are a lot of good reasons to go with steel. It is repairable. A good frame builder can re-tube a frame, remove dents, or realign a bent frame with a minimum of hassle and expense. Years of cycling have convinced me that steel continues to offer the best balance of ride quality, comfort, and performance- especially over longer distances. Modern tubing like Reynolds 953 or True Temper S3 can be used to build some very lightweight, but durable machines.
Aluminum should be avoided. Aluminum tubing is rigid and translates road shock, resulting in a harsh uncomfortable ride, especially over longer distances. It just isn’t a good choice for this sort of bike, despite the potential for light weight.
For longer rides and commuting it is often desirable to be able to use a loaded handlebar bag. Low trail steering geometry results in better handling with a front load.
There are a few other things that I think should be considered, but aren’t necessarilly defining:
Extras Are Easy to Remove:
In my view, components like fenders and lights should be easily removable for times when conditions are good and you want to shed the extra weight to get that little added bit of performance.
One of the main things that I feel differentiates a sportive bike from a randonneuring bike is the absence of integrated lighting on the sportive bike. Many people will use their sportive bikes as their everyday commuters. This means riding home at night during the winter. On longer rides it isn’t unusual to get caught out close to dark. Both these things make the ability to use lights desirable. A well-thought-out sportive bike might make provisions for smoothly, elegantly, and securely mounting the rider’s intendend lighting such as braze-ons for taillights and a mounting position for the headlight on the fork, axle, or bag support if used.
In most cases I feel that a cycle sportive bike should have vertical dropouts, so the wheel can be easily removed with the fenders installed. However, there is a lot to be said for taking your fancy drivetrain off and running a fixed-gear during the winter to save wear and tear and optimize training miles. If you plan to do this then a horizontal dropout is really the way to go.