We spent countless hours in meetings during the planning of this year's Bible of Bike Tests trying to figure out how to organize these bike comparisons. Would we choose pairings before riding every bike, or after? It's the difference between perceived similarity and actual, and both have merit. It would make sense to perceive the Transition Sentinel and Kona Process 153 29 as similar. After all, both are new 29-inch-wheeled models from Pacific Northwest companies that share a similar ethos of industry flip-offery and limit-pushing bike design, both run 160-millimeter forks, have really steep seat angles, slack head angles and vertically mounted trunnion shocks. It's an obvious comparison on paper, but in reality, those two bikes aren't much alike, especially after Transition went ahead and made the Sentinel carbon.

Luckily, we let the bikes speak for themselves and discovered a pairing nobody expected—one that's hopefully a lot more useful. Orbea and Transition probably don't have a ton of customer crossover, yet with an entire continent and ocean between them, both made remarkably rad modern 29ers with far more in common than we'd ever expect.

Transition Sentinel Carbon x01

The Transition Sentinel Carbon X01 is $6,000.

At the heart of all Transition's new bikes is a concept they call Speed Balanced Geometry, or SBG. Essentially, it pairs a slacker head angle with a fork that has reduced offset. Funny, it was only a couple years ago that bike manufacturers convinced fork companies to make longer offsets.

Those longer-offset forks were meant to decrease trail to achieve quicker handling. SBG's short-offset forks run contrary to that trend by deliberately increasing trail. The idea is to get the benefits of a slack head angle by reducing offset in order to keep the front wheel within eyeshot. Transition claims SBG creates bikes that handle well at all speeds, with stability on steep descents, but easy maneuverability everywhere else. Sounds great, doesn't it? So, does the Sentinel Carbon deliver on that promise?

In a word, no, but it's not that simple, so maybe yes. The Sentinel has extreme numbers, and it requires getting used to. At 475 millimeters, the reach of the size Large is huge. Then, it has a 64-degree head angle. The short-offset fork reins things in, and the 76.3-degree seat angle makes the bike climb surprisingly well, but it's still very long and very slack—there's no hiding that.

The Sentinel is equipped with a middle-of-the-road 140-millimeters of rear travel.

The rad part is, the Sentinel rides with more agility than a bike this slack should. Increasing trail should create more sluggish steering, but it didn't do that on the Sentinel. Testers didn't encounter front wheel wandering or flopping about when climbing. When we switched the lever on the Fox DPX2 shock to Pedal mode, the Sentinel even climbed well. In the Open position, the suspension remained active enough for some of us to want to reach for the lever on super steep climbs, but the 76.3-degree super steep seat angle saved us from needing Pedal mode on every incline, as did the relatively short, 140-millimeter progressive suspension.

When experiencing how hard this bike charges the steeps, the fact it survives the climbs at all is amazing. Radical riding angles are where the Sentinel begins to really dance and play, and it's here that it corners better than everything else. It has stability in spades. Its 140-millimeters of travel feels deeper, allowing the bike to eat up big hits, while delivering enough pop to turn tiny rollers into senders.

Long-wheelbases make for more stable bikes. The Sentinel’s wheelbase is about as long as they come.

As a 140-millimeter-travel bike, you might mistake the Sentinel as a well-rounded all-mountain bike, but don't let that fool you. There's no hiding a 64-degree head angle or 1,247-millimeter wheelbase. On mellow descents, you need to adjust your riding position way over the bars in order to get the front end to hook up, like a downhill bike requires. SBG does make you feel more balanced and it does keep the wheel from flopping around. It doesn't behave like a bike with such a slack head angle until it understeers like one.

The Sentinel really does up the ante for overall capability, and could usher in a new level of single-crown shredding. If that's your game, the Sentinel might be the ticket.

Bible Review: Transition Sentinel Carbon x01

Orbea Rallon Team

The Orbea Rallon Team is $8,000.

It wasn't until well after we chose to compare the Rallon and Sentinel that we learned just how perfectly fit they are for comparison. We'd ridden every bike in the category and decided these two bikes were similar but different enough for a head-to-head. Then we packed up, went home and started wading through piles of numbers and specs—and there it was on Rallon's geometry chart: fork rake 44 millimeters, same as the Transition. The only two bikes in the entire test with increased trail, and we put them together without having known it beforehand. We felt supremely smart, while simultaneously feeling stupid. How could we have missed it? Well for starters, Orbea didn't tell anyone.

But it must have contributed to the two bikes feeling similar, right?  Maybe, but who knows. A lot of it was suspension feel—both bikes are supple yet progressive. Then there's also that they both have 29-inch wheels, 160-mil-travel Fox 36 forks, 435-millimeter chainstays, steep-ass seat angles and nearly the same stack and bottom-bracket heights. Standover is the same too if you measure where it matters, 6 inches in front of the tip of the saddle. They even have pretty much the same seat tube lengths.

The offset shock gives the Rallon a unique look and allows for an extra frame support, giving the bike an overall stiffer frame.

That's a lot of similarity, but the numbers that are different are a lot different. The Rallon's head angle is a full degree steeper than the Sentinel's—a degree and a half in the high position. Plus, the Rallon's reach is 20 millimeters shorter than the Sentinel's, while the wheelbase is 30 millimeters shorter. Those aren't minor differences.

We're not saying the Rallon is short or steep, it comes in two settings: Low and Lower. Cute. Lower grants 65 (65.5 in low) degrees—slack for a long-travel 29er, the Evil Wreckoning is steeper, and a sensible reach of 455 millimeters for a size Large. Orbea chose to stick a shorter-offset fork on a less radical bike than Transition did.

It worked out really well. The Rallon is an enduro weapon that feels at home on the local trail loop. It's quicker, with more agile steering that's much more agreeable on mellower grades than the Sentinel. The Sentinel doesn't love to turn on anything that's not a double black. The Rallon is less aggressive, but that makes it a more well-rounded machine.

Up or down, Travis Engel was impressed by the Rallon and its lively manner.

Despite it having 10 millimeters of additional rear travel, the Rallon climbs more efficiently than the Sentinel. We didn't find ourselves reaching down quite as often to activate the Fox Float X2's pedaling platform, although it did come in handy for longer slogs and fire-road climbs. As with the Sentinel, the steep 76-degree seat angle was appreciated on the climbs.

Even with its longer wheel travel and burlier shock, the Orbea didn't out-descend the Sentinel, but it's still a pro. It's poppy and playful at speeds slower than a bike this big should be, but handles the steeps with ease. The Sentinel is an unapologetic downhill addict. If you are too, you should probably take one for a spin—and do so someplace very, very steep. But the Rallon is great everywhere, not just when things get vertical.

Bible Review: Orbea Rallon Team

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