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Shimano Dura-Ace Di2 vs. SRAM RED AXS: Our Uncensored Opinions

Craig has a 12-speed Shimano Dura-Ace Di2 group. Justin has a SRAM RED AXS group. We asked them to switch bikes and compare drivetrains. Which of these top-tier groupsets is the best? Craig and Justin gave us their honest thoughts.

Written by: Bruce Lin

Published on:

Posted in:Features

A few weeks ago, SRAM launched an updated version of its flagship RED AXS groupset. Our Purchasing Manager, Justin, has had a test group installed on his ENVE Melee for the past few months and he’s been super happy with the performance. 

Craig, our Receiving and Catalog Supervisor, has been a die-hard Shimano rider for years, and currently has the latest 12-speed Shimano Dura-Ace Di2 group on his Specialized S-Works Tarmac SL8. He's said that he isn’t interested in riding anything else. 

Justin and Craig ride the same size bike, so I saw an opportunity to do a side-by-side comparison of the two best drivetrains on the market. I asked them to switch bikes so they could compare drivetrains. Here is what happened:

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Dura-Ace vs. Red: Ergonomics

The biggest difference both Justin and Craig noted immediately was the ergonomics of the levers. The new SRAM RED AXS shifter hoods have been completely reshaped and are significantly longer than the Shimano Dura-Ace hoods. Both riders liked the ability to fully wrap 3 fingers under the hoods, which provides a very secure grip and they both rated the comfort very highly.

Craig did prefer the paddle shifter arrangement on Dura-Ace (rear derailleur on right, front derailleur on left), but did concede that he is simply more used to them. 

Winner: SRAM

Dura-Ace vs. Red: Rear Shifting

Both systems shift very well. They’re both top-of-the-line groupsets, so that’s to be expected. But both Justin and Craig agreed that Shimano is smoother and more refined.

Dura-ace is “crisp,” while RED feels a bit more “clunky” in comparison. Is that bad? Not necessarily. Both agreed there was no real performance difference. It was mostly about the sensation of shifting, and in that respect, both thought Shimano still had a slight edge. 

Winner: Shimano

Dura-Ace vs. Red: Front Shifting

Front shifting was no contest. The Shimano front derailleur was noticeably faster, especially when shifting from the small to the big ring. Does this provide any performance benefit? Both Justin and Craig were doubtful. They agreed that SRAM’s front shifting still felt very good and reliable. If if front shift speed is something you care about though, Shimano is the clear winner. 

Winner: Shimano

Dura-Ace vs. Red: Gearing

On the pedals, neither rider could really tell a difference. Craig maybe wanted a larger big chainring than the 48/35t combo Justin’s RED group offered (Craig’s Dura-Ace group has 52/36t chainrings), but that is a small critique because larger chainring options are available. Both agreed that, overall, there was no real noticeable difference. Both systems were quiet, had nice small jumps between gears, and provided a decent climbing gear for super steep climbs.  

Winner: Draw

Dura-Ace vs. Red: Brakes

Both Justin and Craig agreed that SRAM RED AXS might have the best drop-bar brakes currently on the market. The SRAM brakes aren’t necessarily more powerful than Shimano’s brakes, but thanks to the revised pistons and pivot points, they require much less effort to access that power. 

Craig was extremely impressed with the ability to one-finger brake from the hoods. Paired with the security offered by the reshaped hoods, he said that RED AXS might be the best option for gravel riding. The braking performance alone was enough for Craig to consider using RED AXS on a future bike build, and it’s the main reason Justin wants to stick with RED AXS for the foreseeable future. 

Winner: SRAM

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