Shimano STI shifters: do they come in different sizes?

Question

I was sure that there's only one size for Shimano road bike shifters. But now I'm helping a friend to choose a bicycle and it seems that a lot of them have bigger shifters judging by images that I'm looking at. Is this just my perception or do they frequently come in different sizes?

EDIT: is it possible that disc brake shifters are larger than rim ones?

Answer 1

Yes.

Shimano introduced the 3300 STI in 1999, which has a downshift lever on the hoods, and reach adjust via screw (the main models had only rubber shims to adjust reach). This continues today as Tourney ST-A070. Generally people are quite rude about this as it is 'not pro' but it will suit some people better.

The third release of Dura-Ace brifters was 7800, and these reduced the grip circumference by 5mm compared to earlier releases, to fit smaller hands, as such products tend to be designed for average-sized men, not women or men with small hands.

7800:

vs 7700:

R700 was then a specific 'small hands' short reach model

The introduction of a hydraulic master cylinder complicated the design. The first one was Di2, which meant no mechanicals and buttons for shifting so these weren't too huge

Shimano has a habit of making clunky shifters for the low-end, and because they were charging exorbitant premiums for hydraulic brifters, came out with ST-RS405 as a cheaper version, which caused many complaints because of its bulbous shape

The pointless (and now cancelled) 'urban' groupset Metrea also experimented by moving the bleed port around which resulted in this monstrosity

Eventually Shimano settled on a hydraulic design which was not too ugly and which is now basically standardised across the range (small differences for gravel, and a bit smaller for Di2):

The one above is ST-R7020, there is also ST-R7025

which is the same but with 4mm less reach, for smaller hands (these brifters all now have screw adjustment as well). Similar models are R8020 vs R8025, and 4720 vs 4725

So several different current sizes:

1. Di2 (because no mechanical shifting) + cable brakes
2. Di2 + hydraulic brake
3. Tourney A070 hood shift type
4. Mechanical hydraulic brakes (plus various discontinued versions)
5. Closer reach version of the above
6. Mechanical cable brakes (plus various discontinued versions)
7. GRX Di2 hydraulic (higher hood because 'gravel')
8. GRX mechanical hydraulic

Answer 2

To condense the information in @thelawnet's answer:

1. Shimano's hydraulic brake levers (with mechanical shifting) are overall larger than their rim brake levers. This is because the master cylinder takes up space. There's no way around this; SRAM and Campagnolo have even more taller bulges at the front of their levers.
2. There's sort of an exception here: Di2 hydraulic levers are about the same size as mechanical rim brake levers. The electronic internals are more compact than the internals for mechanical shifting.
3. One model of shifter - the R7025 STI lever, which is 105 level, hydraulic disc, mechanical shifting - is a "small hands" version. The reach, i.e. the shift lever's distance from the handlebar at rest, is 4mm shorter than other Shimano shifters. In all cases, you can vary the lever reach by (I think) 15mm. I believe the R7025 STIs are also slimmer.

I believe that the section of the shifters that you grip is roughly the same size in all models regardless of hydraulic disc or rim brake, except for the R7025s.

Answer 3

Mechanical shifters are bigger than electronic units, high end units are smaller and sleeker because more ergonomically designed.

Disk brake shifters that need to house the fluid reservoir and the master cylinder have started bigger but have become smaller over the years with little or almost no visible difference to rim brake units.