Mechanical Shimano 105 goes 12-speed and is disc-brake only
New mechanical groupset benefits from trickled down tech from 105 Di2, Ultegra and Dura-Ace ranges.
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After the release of an electronic 105 groupset last year, which caused controversy in some quarters, Shimano has updated its popular 105 mechanical groupset for the first time since 2018. The new release takes inspiration from the electronic Di2 version released last year, in that mechanical 105 has now gone 12-speed for the first time.
There’s bad news for rim brake aficionados as the new R7100 groupset is only compatible with hydraulic disc brakes, once again following the lead of the Di2 version which shunned a rim-brake option from its line-up.
The new groupset falls under the brand’s Science of Speed umbrella, a design philosophy used by Shimano to design its latest groupsets including the newest Ultegra and Dura-Ace options, and it benefits from plenty of trickle-down technology from higher up Shimano’s hierarchy.
The groupset has a new rear derailleur which can support a maximum 36t cog, while there’s a choice of either a 52/36t or 50/34t chainset.
12-speed in, 11-speed out
Once Shimano released the 12-speed Di2 105 groupset last year, it was only a matter of time before that 12-speed technology trickled down to the mechanical groupset.
Naturally, that led to rumours that have been fanned multiple times over the last year, most recently by Bianchi who listed a 12-speed mechanical 105 groupset on the spec sheet for its updated Sprint bike.
That groupset, as expected, has been confirmed as the latest iteration of the mechanical 105 which jumps to 12-speed for the first time. In doing so, it takes the same crankset and cassette options used on the Di2 version.
This includes a new rear derailleur which can support a maximum 36t cog. Previously the maximum was 34t, and this opens up the possibility for a sub one-to-one gear ratio when a 50/34t chainset is combined with an 11-36t cassette. All of the cassettes in the new range are compatible with Shimano's 11-speed freehubs.
Shimano 105's new rear derailleur supports a maximum 36t cog
Alongside the 50/34t option, the Hollowtech II crankset is also available in a 52/36t offering.
There’s also a choice of 160mm, 165mm, 170mm, 172.5mm or 175mm-long crank arms.
All-in for disc brakes
There is only a disc-brake version of the new groupset
Shimano’s choice to omit a rim-brake option from the line-up is both surprising and unsurprising. It follows the trend set by the Di2 version of the groupset which is also only available in a disc brake option.
However, it’s a step the brand hasn’t taken with either the Ultegra R8100 or Dura-Ace R9200, meaning the 105 is the first of the brand’s groupsets to go completely disc brake-only across its full range.
That’s sure to stir a few anti-disc rumblings. Considering how many brands are only making disc brake versions of their bikes, the decision makes sense.
The hydraulic braking system in question uses new Shimano 105 R7100 calipers. These are similar to those used in the Di2 version and benefit from trickled-down technology from the Ultegra and Dura-Ace ranges, including a new bleed port which simplifies the bleed process.
They also have 10% more clearance from the rotors, helping to eliminate any brake squeal - something any rider can appreciate.
New shifting ergonomics
The 12-speed gearing and disc brakes are operated by ergonomically-enhanced levers which are designed to fit any hand shape or size.
According to Shimano, the new levers provide a “relaxed shifting experience”, providing “comfort and control during your ride”.
The whole system weight with an 11-34t cassette and 50/34t chainset clocks in at a very respectable 2,369g (without a chain and calipers), according to Shimano. That’s a little heavier than the Di2 version, which is to be expected.
We’re really excited by the latest release of one of Shimano’s most popular groupsets and were lucky enough to test the new 12-speed 105 ahead of launch. Watch the full video at the top of this page.
To explore the full range, head over to Shimano’s website.
Online Production Editor
Tom is our Online Production Editor who creates tech content for the GCN website