The Shimano FD-4703 [paid link] front derailleur is part of the Tiagra 4700 series, designed for road bikes requiring a triple crankset. In contrast, the FD-4700 [paid link] front derailleur is optimized for a compact or standard double crankset. While both belong to the same 4700 group, their design, compatibility, and performance characteristics differ in ways that matter for precise shifting and long-term reliability. This guide explores the exact distinctions between the two models to help riders choose the correct front derailleur for their drivetrain needs.
Design and Intended Use
The FD-4703 [paid link] is built exclusively for triple chainring setups (50-39-30T being the common configuration). Its cage length and curvature are optimized to accommodate the wide gear range of a triple crankset, ensuring smooth transitions across three chainrings.
On the other hand, the FD-4700 [paid link] is designed for double chainring systems such as compact (50-34T) or standard (52-36T) setups. Its cage is shorter and shaped differently to maintain precise control over a narrower front gear range.
The practical takeaway is straightforward: FD-4703 [paid link] cannot deliver reliable performance on a double setup, and FD-4700 [paid link] will not function correctly with a triple.
Cable Pull Ratio and Shifter Compatibility
Both models use Shimano’s new cable pull ratio introduced in the 4700 series. This ratio differs from earlier Tiagra generations, meaning FD-4703 and FD-4700 require Tiagra 4700-compatible shifters. Attempting to pair them with older 10-speed shifters (such as Tiagra 4600) will result in misaligned shifting and poor indexing.
However, within the 4700 series, FD-4703 pairs only with the ST-4703 triple shifters, while FD-4700 is compatible with ST-4700 [paid link] double shifters. Mixing across triple and double systems will lead to incorrect cable tension and unusable gear ranges.
Mounting Options
Both derailleurs are available in braze-on and clamp band versions. The mounting style does not differ between FD-4703 and FD-4700, making frame compatibility straightforward. Riders selecting between the two should base the decision purely on their crankset type rather than mounting concerns.
Adjustment Range and Chainline
The FD-4703 features a wider adjustment capacity due to its triple-specific cage design. It is optimized for a chainline of 45 mm, which matches Shimano’s triple cranksets. This geometry ensures chain stability across the large chainring spread.
The FD-4700 also works with a 45 mm chainline, but its cage is optimized for narrower front ranges. When forced onto a triple crankset, the chain would rub heavily, leading to inefficiency and premature wear.
Weight Differences
Both models share similar construction materials, with aluminum plates and steel pivots for strength. However, due to its longer cage, the FD-4703 typically weighs slightly more than the FD-4700. The difference is minor, but riders concerned with weight may note that the double-optimized FD-4700 is the lighter option.
Performance on the Road
With proper setup, the FD-4703 delivers consistent shifting across a triple chainring. Its longer swing arm provides extra leverage to move the chain smoothly between the wide range of gears. This makes it ideal for touring, climbing, and endurance riding where a broad gear range is essential.
The FD-4700 offers crisper, quicker shifts across two chainrings. Because its cage does not need to travel as far, it feels more responsive under high pedaling loads, making it the better choice for performance-oriented road cycling.
Durability and Maintenance
Both models share similar construction quality, meaning their durability is nearly identical under proper care. Regular cleaning, lubrication of the pivot points, and correct cable tension will extend lifespan significantly. Riders using FD-4703 may need to fine-tune adjustment screws more frequently, given the wider range of movement required for triple shifting.
Price and Availability
FD-4703 is slightly less common, as triple cranksets are less popular in modern road cycling. FD-4700, by contrast, is widely available due to the dominance of double crankset setups. Riders building a touring or endurance bike may need to source FD-4703 from specialist suppliers or online marketplaces, while FD-4700 is readily stocked in most local shops.
Which One Should You Choose?
The decision between Shimano FD-4703 and FD-4700 is entirely dictated by your crankset:
- Choose FD-4703 if you are running a triple crankset and need maximum gear range for climbing and touring.
- Choose FD-4700 if you are using a double crankset and want faster, more precise shifts for performance cycling.
Attempting to interchange these derailleurs outside of their intended crankset type will lead to poor shifting and drivetrain inefficiency.
Conclusion
The Shimano FD-4703 front derailleur and the FD-4700 may belong to the same Tiagra 4700 series, but their applications are not interchangeable. The FD-4703 is purpose-built for triple setups, offering versatility and range, while the FD-4700 is tailored for double cranksets, providing speed and precision. Riders must match the derailleur to their crankset and shifter system to achieve the smooth, reliable shifting performance that Shimano designed these components to deliver.