Shimano has released details of its all new 105 groupset. Revamped for 2014/15, the drivetrain is now 11-speed, with all components gaining trickle down technology from the company's existing Ultegra and Dura-Ace groups.
Importantly, the new 105 can also be combined with Shimano's recently announced, second generation hydraulic disc brake for road bikes – in a system that debuts mechanical shifting with hydraulic braking for the company.
There are several chainset options for the new 105 including the FC-5800, a new four-arm Hollowtech II design similar to that of current Ultegra and Dura-Ace. it's stiffer and lighter than the five-arm design it replaces, and Shimano has reinforced construction around the chainring area to further improve the stiffness to weight ratio. The chainset uses the same bolt circle diameter for compact and traditional double chainsets, which means one crankarm fits all chainring sizes.
Gearing options are as follows: 50-34t, 52-36t or 53-39t, and both black and silver colour options will be available. The crankset can be used with Shimano's SM-BBR60 bottom bracket or, should your frame require it, the SM-BB72-41B press-fit bottom bracket.
Shimano will also continue to produce five-arm Hollowtech II chainsets in all popular gear combinations for the 105 group. Crank length options will be 165mm, 170mm, 172.5mm and 175mm.
ST-5800 dual control shift levers
105 now gains the light yet positive shift action found in Dura-Ace and Ultegra levers; there's also a new compact shape that's borrowed from the the levers of Shimano's more expensive groups. The lever can adjusted to accommodate different hand sizes via a 10mm screw-type reach adjustment. Polymer coated cables are now standard.
FD-5800 front derailleur
The new 5800 front derailleur has a longer link arm and a new spring mechanism when compared with the last generation component.
RD-5800 rear derailleur
Shimano has included a new spring mechanism and cable pitch in the latest 105 rear derailleur, said to provide robust adjustability. Both SS (short) and GS (long) options will be available, with the latter being compatible with a 32t cassette.
BR-5800 caliper brakes
105's has taken a step up to a new symmetrical dual pivot caliper design, with a higher arch allowing clearance for up to 28mm-wide tyre. The result is a claimed 10% increase in power. Direct mount versions will also be available (BR-5810-F/R).
105's 11-speed cassette is offered in three flavours providing the following ratios: 11-25t, 11-28t and 11-32t. Each choice uses close ratios that Shimano say optimise rhythm and cadence control.
The new CN-HG600 11-speed chain uses Shimano's low friction surface treatment known as Sil-Tec. It's a PTFE surface coating that reduces friction while boosting durability. The technology first debuted a couple of years back on Shimano's flagship Dura-Ace 9000 chain.
Hydraulic disc compatibility
The big news is that Shimano has now expanded hydraulic disc technology to work with a mechanical drivetrain rather than the Di2-only previous components. This has been achieved by the company introducing the ST-RS685, a new dual-control lever that houses 11-speed shifting internals alongside the guts of Shimano's hydraulic brake. The 11-speed shifter can be paired with the drivetrain of Shimano’s Dura-Ace and Ultegra mechanical groups as well as this latest version of 105.
Both the ST-RS685 shifter and the new BR-RS785 hydraulic disc brake will remain a non-series component, meaning they won't belong to a particular product group such as Ultegra or Dura-Ace.
Flat handlebar shifter
Shimano has decided to offer another non-series component that builds on the versatility of the 105 group: a pair of 11-speed flat bar shifters. These should provide a decent option for manufacturers or individuals looking for premium shifting on flat bar hybrids without having to resort to often overbuilt mountain bike components. Once again these parts will work with Shimano’s Dura-Ace and Ultegra mechanical .
Details are scarce on 105's new pedals at the moment, but we are expecting to see both carbon and resin versions available – the former shaving 50g over the current alloy models at 285g.
The groupset will be available in black and silver options with stock expected from June 2014.