Two days ago this site looked at the Cube Fritzz, which runs a 435mm chainstay on every frame from S to XL, and argued that the choice is defensible on a high-pivot bike whose rear centre moves through travel anyway. The Yeti MT is the other answer to the same question, from a brand that built a prototype specifically to test six different rear centre lengths before committing.
So the MT scales its chainstays. The interesting part is how little that changes.
The chart
| S | M | L | XL | |
|---|---|---|---|---|
| Reach | 430 | 460 | 480 | 505 |
| Stack | 617 | 625 | 635 | 650 |
| Head angle | 64.5° | 64.5° | 64.5° | 64.5° |
| Seat angle | 77° | 77° | 77° | 77° |
| Chainstay | 436 | 440 | 446 | 452 |
| BB height | 342 | 342 | 342 | 342 |
Source: Pinkbike’s first ride, corroborated by BikeRadar, which independently reports the same 64.5 degree head angle, 77 degree seat angle, and a chainstay running from 436mm on the small to 452mm on the XL. Worth saying plainly: Yeti’s own product pages present the geometry visually rather than as a text table, so these numbers come from the press rather than from the manufacturer directly. Cross-check before you order a frame.
Four sizes. No adjustment, no flip chip, no headset cup in the stock build. The head angle and seat angle are identical on every frame, which is less common than it sounds and makes the size comparison unusually clean.
What 16mm of chainstay actually buys
Here is the arithmetic the launch coverage skips. Reach grows 75mm from S to XL. Chainstay grows 16mm. The front of the bike is stretching roughly four and a half times faster than the back.
The usual argument for size-specific chainstays is that they hold the rider in the same place between the wheels, so an XL rider gets the same handling the small rider gets. Run the numbers and that is not quite what happens. Take the rear centre as a share of the two measurements combined, which is a rough proxy for how much of the bike sits behind you. Working from the chart above, the small puts 436 of 866mm behind the bottom bracket, or 50.4%, and the XL puts 452 of 957mm, or 47.2%.
That is a drift of 3.1 percentage points across the size run. Now do the same for the Fritzz, which scales nothing at all: 50.5% on the S, 46.7% on the XL, a drift of 3.8 points. Those are our own calculations from the chart above and from the Cube Fritzz chart we published on Tuesday, not figures either brand quotes.
Yeti’s 16mm of chainstay scaling recovers about 0.7 of a percentage point of balance drift compared with a brand that does nothing, working from the published MT chainstay range of 436 to 452mm. Both bikes move the tall rider forward relative to the rear axle as size goes up. One does it slightly less.
None of which makes the scaling pointless. Sixteen millimetres is real, and an XL rider will feel it in how readily the front wheel lifts. But a rider choosing the MT over a fixed-stay competitor because “it is size specific” is buying a much smaller correction than the phrase implies, and it is worth knowing which part of the marketing is doing the work.
Sixfinity, and why the rear centre is not really fixed anyway
The MT runs 140mm of rear travel through Sixfinity, the six-bar layout Yeti developed on its 160e and its Special Projects downhill bike before bringing it to the pedal bikes. Yeti’s own framing is that the MT “uses the magic of Sixfinity’s six-bar design to reward speed”, which tells you what they were optimising for and not much else.
What matters for this discussion is that a six-bar, like the Fritzz’s high pivot, puts the rear axle on a path rather than an arc around a single pivot. The 436mm on the small frame is the number at one point in the travel, not a constant. This is the same caveat the Fritzz piece ended on, and it applies to both bikes: every static chainstay figure in a geometry chart is a snapshot of a moving part.
The practical consequence is that comparing two modern bikes on published chainstay alone is less informative than it was a decade ago, when most rear ends rotated around one bearing and the number meant roughly the same thing at sag as at top-out.
Front travel is 160mm, on a Fox 36. A 160mm fork on a 140mm frame is a deliberately front-heavy pairing, and combined with the 64.5 degree head angle it explains why Yeti keeps describing a 140mm bike in language usually reserved for enduro bikes.
Stack is the number to check before you size up
The stack figures are the ones most likely to catch someone out: 617, 625, 635, 650. That is 33mm of growth across the range, and Yeti has deliberately raised it, saying the taller stack “puts riders in a more neutral position” with more comfort when the trail points down.
A rider between sizes is therefore choosing 30mm of reach and 15mm of stack at the same time, which is a bigger change in riding position than the reach number alone suggests. If you size up for the reach you also get a noticeably taller front end.
There is one adjustment available and Yeti buries it. The MT is built around a ZS44/56 head tube with what the brand calls “integrated alignment notches for proper cup positioning”, which means aftermarket offset headset cups will fit and are the intended route for anyone wanting to shift reach without changing frame size. That is not a flip chip and it is not free, but it exists, and it is the only geometry adjustment on the bike.
Where it lands
TURQ carbon with Vectran plies, four builds, and a weight of 33.1 lb or 15.01 kg for an XL in the X0 build, which is honest rather than flattering for a 140mm carbon trail bike.
Frames are $4,600 through dealers only. Complete bikes run from $8,000 for the X0/90 to $11,500 for the XX AXS, with an XT Di2 build at $8,500 and the X0 AXS at $9,800 sitting between them, per Yeti’s own kit listings.
The MT is the more conventional of the two bikes covered here this week, and conventional is not a criticism. It has a constant head angle, a constant seat angle, a constant BB height and a rear centre that grows with the frame. That makes it one of the easier charts in this category to reason about, which matters more than whether the scaling is as decisive as the category’s marketing suggests.