Best Price Shimano Groupset UK 2026: 105 Di2, Mechanical & Upgrades
5 August 2026 · Laura Mcmahon
Search “Shimano 105 Di2 UK” and you will see £749, £1,000 and an RRP north of £1,700 for what looks like the same groupset. The listings are mixing model numbers, crank lengths and whether the shop included a bottom bracket.
This guide is about complete groupsets, not complete bikes. It covers 105 mechanical and Di2 street prices, when Ultegra or GRX is worth the extra, what is actually in the box, and the freehub trap: road 12-speed uses Hyperglide+, not Micro Spline (Micro Spline is the MTB 12-speed standard).
Who this is for: frame-up builders, crash replacements, and anyone comparing a bare kit with a complete bike deal.
105 Di2 (R7170 / R7150), 12-speed hydraulic disc: sale kits commonly £749–£1,000 depending on crank, cassette and whether wires, battery and rotors are in the bundle. Launch RRP was widely reported around £1,730, so 40–55% off is a real window, not a sticker trick.
105 mechanical (R7120 / R7100), 12-speed hydraulic disc: sale kits from around £559 upwards. Simpler, no battery, cables you (or a shop) can service with a screwdriver.
Always read the spec line. Bottom brackets, disc rotors and Di2 wire lengths are the usual omissions.
If you want electronic shifting at a sensible outlay, Di2 at current UK sale prices is the value story. If you want to keep life simple and put the difference into a frame or wheels, mechanical 105 12-speed is still an excellent drivetrain.
Model numbers
System
Key codes
Type
Speeds
105 Di2
ST-R7170, RD-R7150
Electronic
12
105 mechanical
ST-R7120, RD-R7100
Mechanical
12
Ultegra Di2
ST-R8170, R8100 series
Electronic
12
Dura-Ace Di2
R9270 / R9200
Electronic
12
GRX Di2
RX825 / RX817 class
Gravel electronic
12 / 2x
R7170/R7150 are Di2. R7100/R7120 are mechanical. Search results that mix them are why two “105” prices look insane next to each other.
Price also moves with crank length (165–175 mm), chainrings (50/34 vs 52/36) and cassette (11-30 through 11-36).
105 Di2 deals
Merlin, Sigma, Fawkes-style configurators and Condor all list R7170 disc kits. The spread from roughly £749 to £1,000 is almost always bundle contents: rotors in or out, BB in or out, cassette range, crank length, Di2 wire set.
No firmware, no charging cable, barrels and a derailleur. At around £559 on sale versus Di2 in the mid-£700s, the electronic premium is real but not enormous. Mechanical needs cable replacements; Di2 needs a frame that can hide the battery and a USB charge every so often.
If Di2 is not a requirement, mechanical 105 12-speed is the kit that frees budget for tyres and a better wheelset.
Ultegra Di2, Dura-Ace, GRX, MTB
105 Di2 and Ultegra Di2 share the 12-speed semi-wireless platform. Ultegra is lighter and a bit more refined under load. For sportives and club miles, 105 Di2 at sale price is the sensible buy. Ultegra (R8170) and Dura-Ace (R9270) are race-budget decisions.
GRX is the gravel conversation. Do not assume a road 105 cassette is the right spare for a GRX bike — check the derailleur capacity and freehub.
MTB 12-speed (SLX, XT, XTR, many Deore 12s) often uses Micro Spline. Road 12-speed 105/Ultegra/Dura-Ace cassettes use Hyperglide+ on a road freehub. They are not interchangeable. Buying a “12-speed cassette” without naming the spline is how you own an expensive paperweight.
What is in the box (and what is not)
Typical full kit: shifters, both derailleurs, chainset, cassette, chain, disc calipers. Di2 adds battery, charger, junctions and E-tube wires.
Commonly missing: bottom bracket (BSA / BB86 / T47 is frame-specific), rotors, mechanical outer housing, and Di2 wires in the lengths your frame needs. Configurator shops cost more because they let you add those lines. Core-only kits look cheaper until checkout.
Cranks, rings, cassette
Most UK riders: 170 or 172.5 mm, 50/34 compact, 11-32 or 11-34 cassette. That pairing covers sportive hills without a 53/39 ego tax. Match existing crank length unless a fitter told you to change.
Before you click buy
BB shell standard
Di2 battery routing (Di2 only)
Rotor size and flat-mount vs post-mount
Hyperglide+ freehub on the rear wheel for road 12-speed
Crank length you actually need
A complete bike already specced with 105 Di2 often beats a fancy frameset plus a £749 kit plus wheels and bars. If you are flexible on the frame, read Shimano 105 road bikes before you commit to a bare groupset.
FAQ
Why do two 105 Di2 kits differ by hundreds of pounds? Crank length, cassette range, and whether the BB, rotors and Di2 wires are included. Read the spec, not the title.
How do I check the frame is compatible? BB shell, hanger, flat-mount vs post-mount, rotor size, and Di2 battery routing. The manufacturer spec sheet beats a forum thread.
What charges a Di2 groupset? The internal battery and the E-TUBE app for firmware. The charge cable is sometimes a separate line item.
Should I buy a bare groupset or a complete bike? If you already have a frame, buy the kit. If you are flexible, a complete 105 Di2 bike often costs less than frameset + kit + wheels. See the 105 road bikes guide.
