As you can see there isn't a huge amount of difference in the weight of these two so the biggest difference is that the Tiagra brake levers run a 10-speed system whereas 105 is an 11-speed.

Aside from the chainset, the new shifters are the most visible change from the previous Tiagra groupsets. The gear indicator windows have been lost and the size and shape are much like 105. Shimano says: "For the first time in its history TIAGRA supports internal cable routing, which gives the road bike a much more clean and professional look. Along with internal cable routing TIAGRA has also adopted the iconic four-arm crank design which is available in the popular gear combination for entry level riders of 52-36T and 50-34T. With the standard pitch cycle (bolt circle) diameter of 110mm both chain ring combinations are interchangeable because they fit on the same crank set. Nobody needs 11t, who is not racing. And 2t jumps are just incredibly annoying, making it impossible to keep a comfortable cadence.With a 105 set-up, it does come with a direct mount option - you will need to ensure that your fork and frame are compatible. A direct-mount option means that the brake arms won't need a central bolt to attach to. Instead, they can be bolted straight to the fork/frame. Shimano claims (and I have no reason to doubt them) that the 11-speed 105 groupset is the most popular in the world. If you do want to take the upgrade route, you need to upgrade a large number of the Tiagra groupset components at once to make it work.

While bikes with Shimano Tiagra are usually substantially cheaper than those equipped with 105, the margin between the cost of components is often a lot smaller Tiagra 4700 is the latest groupset from Shimano to get a makeover, and in doing so it has made Tiagra the best it's ever been. On its own, it's not quite as good as the more expensive 105, but if you're buying a new bike with Tiagra 4700, you won't be disappointed.Tiagra is offered with both a double chainset (there are two chainrings) and a triple chainset (there are three chainrings) whereas 105 comes as a double only.

For riders who need a shorter crankset, they will need to opt for 150 R7000 as it is available in 160mm. If you have smaller hands, then the R7000 brakes are likely to work better. This is because the lever does sit more closely to the handlebar than ST-R7020 levers. It's a groupset that can give you what you want from a mid-tier road bike. Sure, there are a few niggles but they are tiny and can be overlooked. Admittedly, the Tiagra shifting isn't as light but it's forgivable considering the price difference.The other major difference between the two groupsets is that the 105 brakes are considerably better than Tiagra ones. They are a real highlight both in terms of all-out power and fingertip control. Thanks Disfunctional T...& RW, I'll keep an eye on the shifting. Seems OK on the bike stand but past experience tells me that 'on the road' is adifferent matter. It's a Shadow mech and the angle of the cable already looks a bit contorted when attached to below the pinch bolt... Both Shimano Tiagra and Shimano 105 use the same ratio of gear cable pull to rear derailleur movement, so you can fit a 105 derailleur in Tiagra system if you want to