Today, SRAM and TRP both released next-gen mountain bike drivetrains, and they couldn’t be more different despite having the very similar goal of delivering perfect shift performance on any terrain.
Both deserve a bit more than the usual quick Friday recap, so here’s the full details on both.
The TL;DR comparison
The SRAM Transmission is a completely wireless group that fully leverages the standardized frame design created by their Universal Derailleur Hanger (UDH) standard introduced years ago. By replacing the hanger with the derailleur’s body, it assembles the thru axle, freehub body, and derailleur into a single structure that’s much stiffer as a whole.
That, plus extreme shaping of the cassette cogs’ ramps and very deliberate, controlled shift execution, deliver a perfect, smooth, quiet shift under full power on any terrain, all in a robust design that’s nearly indestructible.
The TRP EVO12 contrasts with a fully mechanical system that adds both a clutch and stabilizer to give the derailleur a sturdy shift on any hanger on any bike. Unlike past efforts, they now have their own (very light) cassette, cranks, and chainring.
The move to a complete system gave them control over every element and, they say, delivers shifting performanc on par with XO/XTR Trail. If true, it could be the go-to mechanical group as bigger players go full electric on their top tier groups.
SRAM Transmission Tech Overview
Having ridden this system, there’s no denying it’s a game changer. Shifting is perfect, smooth, and quiet. Everything but the shifters are called T-Type (because it’s a complete “Transmission” that’s meant to work together) and are not interchangeable with other Eagle AXS parts.
Groups:
- XO – Aggressive Trail to Enduro riders
- XX – Trail/Downcountry riders
- XX SL – XC racers
T-Type Rear Derailleur
Because its relation to the XD driver body, frame, and cassette are now fixed as a standard, the derailleur is automatically aligned for perfect shifting as soon its installed.
The “Full Mount” design sandwiches the frame with a CNC’d upper body locked into place with a bolt and the thru axle. It’s strong enough to handle (virtually) any impact or crash without damage, but surface parts can be completely replaced.
The Magic Wheel lower pulley’s outer tooth ring can breakaway and spin on its own, keeping the chain spinning and saving your derailleur if something gets stuck in there and jams the pulley’s hub.
- Hangerless interface, mounts directly to frame
- No B-gap or limit screws, it just lines up on its own
- A/B Cage Lock positions aid initial setup
- Angled Inline Cage keeps chain aimed directly at chainring
- Extremely strong and impact resistant
- Pulley cage twists off for easy, tool-free replacement
- Replaceable Skid Plates keep it looking fresh
- Almost completely rebuildable
- AXS app’s drop-down frame list tells you chain length
- Install is very easy (video here)
Key differences between models:
- XO has stamped alloy pulley cage and bigger Skid Plates.
- XX has CNC’d alloy pulley cage, slimmer lower pulley hub & more machining of upper mount.
- XX SL has most machining, carbon pulley cage & slimmer Skid Plates.
T-Type Cassette
The biggest update is the “Cassette Mapping” design and narrow-wide tooth profiles on all but one cog. Deep shift ramps guide outer chain plates onto the next cog, ensuring a smooth, solid transition onto the narrow-wide interface no matter how hard you’re pedaling.
It sits 2.5mm further outboard than normal, and chain line moves out with it. That’s another reason why you can’t just add the T-Type RD to your existing Eagle group, but the upside is bike brands can use that space to add more tire clearance.
- All cogs except #7 have narrow-wide teeth
- 7th cog is the set up cog
- Intentional single-cog shifts are slower, but solid
- Can shift under full power
- Very quiet shifts and operation
- Mono-bloc 9-cog steel lower piece
- Pinned individual cogs for largest three
Key differences between models:
- XO / XX – Steel 10 & 11 cogs, alloy 12th cog (380g), different finish only
- XX SL – Alloy 10/11/12 cogs (345g)
T-Type FlatTop MTB Chains
The new FlatTop MTB chains are SRAM’s strongest ever. They’re optimized for this group, so you wouldn’t want to run the FlatTop road chain here. If you’re building a mullet gravel drivetrain with a SRAM Road 1x front and T-Type cassette and derailleur, use one of these MTB chains.
Key differences between models:
- XO – standard finish, links & pins (256g)
- XX – Hard Chrome finish, hollow pins (247g)
- XX SL – Same as XX but w/ cutouts on outer pins (240g)
AXS Shifter Pods
New AXS Pod Controllers will work with any SRAM AXS product (road, MTB, gravel, Reverb dropper, Flight Attendant). They come in Standard and Ultimate versions, the latter getting swappable buttons with both convex and concave designs in the box.
Two mounts let it fit any cockpit setup or attach to their Matchmaker brake clamps. Fully programmable through the AXS app, and you can rotate and flip them however you like.
Transmission Cranksets
All three models get new T-Type chainrings that are optimized for the new FlatTop MTB chains and use their 8-bolt mounting standard, letting you add the new Quarq power meter spider to any of them. All models have power meter options that double as Flight Attendant cadence sensors.
XO crankset features:
- AI-designed, lightweight alloy cranks
- Integrated, removable bashguards on chainring
- Optional left-side spindle power meter
- 30/32/34-tooth chainrings
XX crankset features:
- Same as prior XO cranks
- Carbon arms with foam core
- Lighter-weight integrated, removable bash guards
- Optional left-side spindle power meter
- 30/32/34/36-tooth chainrings
XX SL crankset features:
- Same as prior XX cranks
- Hollow carbon arms
- New Quarq PM with new twist-on chainrings
- 32/34/36/38-tooth chainrings
All parts are available at launch in March 2023.
TRP EVO Drivetrains
Yes, TRP knows what they’re up against. They had to work around 15,000+ bicycle drivetrain patents to create 130 of their own.
But they’ve been making shifters and derailleurs for years now, selling tens of thousands to Giant and others for low-end bikes under the Tektro brand.
TRP (Tektro Racing Products) is their premium division and have been making World Cup-winning brakes for Aaron Gwin and others for years, too, while other pros were helping develop the shifting bits. This new TRP EVO12 is the 2nd generation group and is now a complete drivetrain.
This gives them better OEM spec options since they can provide both brakes and drivetrain, and Intense will be the first brand to spec a complete TRP-equipped bike.
They’re offering a virtually identical feature set on the new EVO7 DH group, too, but since most of us would likely be riding a 12-speed “trail” group, I’ll focus on that. And, actually, it’s designed for and has been tested at EWS Enduro racing under Cody Kelley and Seth Sherlock, so it’s capable well beyond “trail” riding.
TRP EVO12 Derailleur
Compared to the original effort, the EVO12 derailleur gets shorter parallelogram arms with horizontal movement and stiffer pins and bushings. The mounting bolt sits inside a band clamp called the Hall Lock. Flip the lever and it prevents any bouncing motion to reduce chain slap.
The ratcheting clutch is replaced with a lighter, silent, one-way roller bearing clutch that makes shifts lighter and easier, too, but still provides solid chain management.
The pulley cage holds 12/14-tooth pulleys with mud-clearing channels. The outer plate is carbon, and the Cage Release lever disengages the spring tension on the chain for easier wheel removal.
TRP EVO Trigger Shifters
The EVO shifters have three unique features going for them. First, a downshift (easier gear) Mode Switch lets you fire through multiple gears with a longer push, or limit it to one click/one gear at a time.
Second, the downshift trigger’s position is easily adjustable.
Third, the cable runs very close to the bar, setting it up for easy “stealth” routing into a headset cup for the increasingly popular full internal routing found on modern bikes.
It’s also a much smaller shifter housing, and internal parts have been minimized to improve durability.
TRP EVO Crankset
Cranksets will come in carbon (165/170mm) and alloy (165/170/175mm) versions with direct-mount chainrings using MRP’s Wave tooth profile and a 30mm spindle. Chainrings come in 30/32/34 tooth counts with 3mm (Boost) and 6mm (DH) offsets.
The spindles have inlaid rubber lip seals where they meet the BB bearings, preventing moisture and dust from getting inside, a very clever and unique feature.
TRP EVO Cassette
The 12-speed cassette is a two-piece unit with the lower 10 cogs machined from billet steel, and the upper two from 7075 alloy to save weight. Tooth counts are 10-11-13-15-18-21-24-28-32-36-44-52 for 520% range.
The two pieces are connected with T25 bolts, making it easy to service, and it fits a Shimano Microspline freehub body. TRP says SRAM’s patents prevented them from integrating the mounting bolt into the cassette, so Microspline offered a better, sturdier, and more secure interface.
The only part of the group they’re not making is the chain. They’re spec’ing color-matched KMC X12 chains, which are very good.
The Takeaway
I’ve ridden both systems and they’re both great. Both are designed to operate best as a complete system, with SRAM basically requiring it. Their move to 8-bolt chainrings means you might even have to upgrade your crankset from the original 3-bolt version.
SRAM’s Transmission elevates shifting performance to the next level, it is simply incredible. But it takes batteries, and you can’t just rip through multiple gears in a flash. Each shift is distinct to allow the chain to time it’s move to the next cog, which is how they’re able to use a narrow-wide tooth profile there and ensure completely smooth, quiet shifts under power.
TRP’s EVO also performs exceptionally well, and I was able to jump multiple gears upon entering a steep pitch without any ill effect. It was remarkably quick and smooth, offering an excellent option for people who prefer a mechanical group. Unlike Transmission, you could add the TRP shifter, derailleur and cassette to your existing crankset with likely no detriment to performance.
TRP’s system will be competitively lightweight -they say the cassette is within 1g of the non T-type SRAM XX cassette- but they haven’t published weights yet. Technically, the official launch isn’t until late April, but I got a sneak peek and short test ride.
Pricing Comparison
Complete Eagle Transmission groups run from $1,599 (XO, no power meter) to $2,699 (XX SL w/ power meter).
TRP EVO12 groups run $994 (alloy cranks, silver finish w/ black & silver chain) to $1,243 (carbon cranks, gold finish w/ black & gold chain).
This is a bonus edition covering two important product launches, but mostly The Lunch Ride is a weekly TL;DR recap of the best new cycling products and tech, written for Riders, not Algorithms. SUBSCRIBE HERE to get it in your inbox every Friday.
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