Shimano Tiagra is a popular groupset on many entry-level road bikes and sits one notch below 105 in the brand’s groupset hierarchy. Tiagra 4700 looks to be filled with trickle down technology and aesthetics seen in current 11-speed Dura-Ace, Ultegra and 105 groupsets. Also announced is a new 105 level hydraulic disc brake system and Ultegra caliper, the brand’s first road disc brakes to receive official groupset labels.
Shimano Tiagra 4700
Surprisingly, Shimano has kept Tiagra 4700 as a 10-speed group, despite all its more expensive groupsets now offering 11-speed. Beyond the number of rear gears, it appears a substantial overhaul has been given to the budget group.
The biggest change is a move to internal cable routing at the shifters, keeping the cables hidden beneath the bartape. Until now, Tiagra used external gear cable housing from the edge of the hood to the nearest cable stop on the frame.
The new shift/brake lever looks to share the compact shape of Dura-Ace, Ultegra and 105. 105 and above features adjustable lever reach via a simple plastic screw, and we expect a similar feature to exist in Tiagra – but it's to be confirmed.
Another key change is a move to a stiffer and lighter four-arm 110BCD crank design, enabling easy swapping between 52/36 and 50/34 chairing sizes. A triple option has been pictured too, although it's unclear if this will be a separate crankset to the interchangeable double option.
Like that of the upper-tier groups, the front derailleur has been improved to offer lower shift effort via a longer link arm. A front derailleur for use with a triple crankset will also be available (pictured right).
The rear derailleur will be available in two cage lengths, with the longer said to be compatible with cassettes up to a 34t. Also, apparently the 'cable pitch' has been revised for improved longevity between servicing.
The dual-pivot rim brake calipers produce a claimed 30 percent increase in braking power, while modulation is said to have improved too. It looks like the Tiagra brakes will stick with one-piece brake pads, instead of the insert-type of models higher up the food chain.
A two-way release flat-bar shifter option will also be available for this groupset.
We’re currently getting more details from Shimano, especially in regards to backwards and cross compatibility, so stay tuned.
Tiagra 4700 is expected to arrive in stores this July, with pricing yet to be announced.
Shimano 105 hydraulic disc brake
The new 105 ST-RS505 is Shimano’s first road hydraulic disc brake to receive official groupset branding – with previous models (launched precisely 12 months ago) given more generic ‘non-series’ branding. A Ultegra RS805 brake caliper has also been mentioned, but no details of a matching lever are available at the time of writing.
These new 105 shifters are fully compatible with current 105, Ultegra and Dura-Ace 11-speed derailleurs.
The 105 shifter/brake lever houses the hydraulic master cylinder and so is longer in length than the equivalent mechanical brake unit. There is 10mm of brake lever reach adjustment available.
Shimano Ultegra RS805 caliper pictured
Both the 105 and Ultegra calipers will use the recently announced Flat Mount standard, aiming for a lower profile and lighter mount specific to road bikes.This new standard should help ease previously difficult tool access on some chainstay-mounted brakes.
The outward hose banjo attachment point at the caliper has been a common complaint with earlier RS785 and RS685 road disc models, sometimes leading to heel rub. The 105 and Ultegra calipers move this rotatable banjo connector to the inside of the caliper for a streamlined and problem-free fit.
Like every other Shimano hydraulic brake, the 105’s will use Shimano’s mineral oil and work with the funnel bleed option.
The currently available RT81-SS 140mm rotors are said to be the matching rotor for the new 105 brakes. These use ICE heat management technology, sandwiching an aluminium core between steel braking surfaces.
The 105-level shift/brake lever and caliper are expected in October, with pricing yet to be announced. The Ultegra caliper is expected in July, so hopefully we’ll hear of a matching lever soon.