Shimano 105 vs Ultegra

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This is the decision most road buyers actually face, and it is normally settled with adjectives. Ultegra is “crisper”. 105 is “almost as good”. Neither statement contains a number, which is convenient for everyone except you.

Shimano runs a public product information database that publishes an average weight and a materials breakdown for every component in both groups. We read it on 17 July 2026 and did the subtraction. Here is what the manufacturer’s own spec sheet says the upgrade buys.

On 12-speed: 40 g on the rear derailleur, 16 g on a like-for-like 11-34T cassette. On 11-speed: 25 g on the rear derailleur. On the chain, both tiers: 257 g each — a difference of zero. And on two components — the 11-speed cassettes and both cranksets — Shimano publishes figures at differentconfigurations, so an honest like-for-like comparison isn’t available at all. We’ll show you exactly where that happens rather than quietly papering over it.

The rear derailleur: the cleanest comparison Shimano gives you

On 11-speed mechanical, Shimano’s spec table lists the Ultegra RD-R8000-SS at 200 g and the 105 RD-R7000-SS at 225 g. Both are short-cage, both take a 30T maximum sprocket, both have 35T total capacity, both use an aluminium bracket body and a GFRP plate body, both use aluminium outer and inner plates. Genuinely the same component at two prices, 25 g apart.

The published construction difference is specific and worth knowing: the Ultegra derailleur lists a guide pulley bearing and a tension pulley bearing. The 105 spec lists neither. That is the clearest example on this page of what a tier actually buys — not a mystery, not a feel, two sealed bearings.

On 12-speed Di2, the gap widens. Shimano publishes the Ultegra RD-R8150 at 262 g against the 105 RD-R7150 at 302 g— 40 g. But note what else changes: the 105 unit takes a 36T maximum sprocket and has 41T total capacity, where the Ultegra takes 34T max and 39T capacity. The cheaper derailleur handles a bigger climbing gear. If your riding is steep, the lower tier is the more capable component on the one spec that affects whether you get up the hill.

The cassette: 16 grams, and a ratio you can't buy at 105

Cassettes are where the tier changes materials, and Shimano publishes the detail. At the one ratio both 12-speed cassettes share — 11-34T — Ultegra’s CS-R8101-12 is published at 345 g and 105’s CS-R7101-12 at 361 g. Sixteen grams.

What the 16 g costs you, in Shimano’s own terms: the Ultegra cassette has two aluminium spider arms to the 105’s one, and an anodised aluminium lock ring where the 105 uses nickel-plated steel. Both carry twelve nickel-plated steel sprockets — the sprockets themselves are the same material. Shimano lists the Ultegra as HYPERGLIDE+ and the 105 as HG.

The more consequential difference isn’t weight at all. Shimano lists the 12-speed Ultegra cassette in 11-30T and 11-34T. It lists the 12-speed 105 cassette in 11-34T only. If you want the tighter 11-30T block — closer ratios, smaller jumps, the thing fast riders on flat roads actually want — it does not exist at 105 in 12-speed. That is a real functional reason to move up, and it has nothing to do with grams.

Where we can't give you a number, and won't invent one

Two comparisons on this page are commonly published elsewhere and shouldn’t be.

The 11-speed cassettes. Shimano publishes the Ultegra CS-R8000 at 232 g at 11-25T and the 105 CS-R7000 at 284 g at 11-28T. Those are different cassettes with different sprockets. The 52 g between them is partly tier and partly the extra teeth, and Shimano does not publish a common ratio for both. So we cannot tell you what the 11-speed cassette upgrade weighs, and neither can anyone else without a scale. The direction is real — Ultegra uses an aluminium lock ring, 105 uses steel — but the magnitude is not published.

The cranksets. Same problem, worse. Shimano publishes the 12-speed Ultegra FC-R8100 at 702 g at 46-36T, and the 12-speed 105 FC-R7100 at 754 g at 50-34T. Different chainrings, different tooth counts, different amounts of metal. Subtracting one from the other produces a number that means nothing. Shimano publishes no common chainring combination for the two cranksets.What it does publish is the material: the Ultegra outer ring is aluminium/CFRP (except at 46-36T), the 105 outer ring is aluminium+GFRP; Ultegra’s chainring bolts are aluminium, 105’s are stainless steel.

This is the part of the comparison that most publishers fill in anyway. We’d rather have the gap on the page. A stated gap is checkable; a confident guess isn’t.

The chain: a difference of zero

Shimano’s chain specifications publish an average weight at a fixed 114 links, which makes them directly comparable. The Ultegra CN-HG701-11 is 257 g. The 105 CN-HG601-11 is 257 g.

The published difference is that the Ultegra chain adds SIL-TEC to the pin link plate — the outer plate — where the 105 chain has SIL-TEC on the roller link plate only. Both get chromizing treatment on the roller link pin. Neither has a hollow pin; that’s reserved for the CN-HG901-11, published at 247 g.

Shimano publishes no wear figure, no durability figure and no efficiency figure for either chain, so there is no way to value the extra coating from the manufacturer’s own data. Our chains roundup ranks the 105 chain above the Ultegra one for exactly this reason, and names the Ultegra chain the one to skip.

So who should buy which?

Buy 105 ifyou ride hills and want the 36T sprocket the 12-speed 105 derailleur supports; if you are building to a budget and would rather put the difference into tyres or wheels, where the published weight differences are an order of magnitude larger; or if you simply want the honest answer, which is that 56 g of measurable difference across a derailleur and a cassette is not a performance decision, it’s a preference.

Buy Ultegra ifyou specifically want the 11-30T 12-speed cassette that doesn’t exist at 105; if you want the pulley bearings on the 11-speed mechanical derailleur; or if you have the money and you want the nicer thing, which is a perfectly respectable reason as long as nobody dresses it up as physics.

Buy neither, yet, ifyour current drivetrain is worn. A stretched chain on Ultegra shifts worse than a fresh chain on 105, and it’s quietly destroying a cassette while it does it — see when to replace a bike chain. And if your shifting is vague, that is far more likely to be adjustment than tier: how to adjust a rear derailleur costs nothing and fixes the actual complaint most of the time.

For where these two sit in the wider range — including what Shimano refuses to publish below 105 — see groupset hierarchy explained.