2021 Transition Spire Carbon GX Bike

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Free shipping on orders over $50 (continental U.S. only).
International shipping available. Some exclusions apply.
Free shipping on orders over $50 (continental U.S. only).
International shipping available. Some exclusions apply.
Vital Test Sessions - Transition Spire
This 170mm 29er defies the numbers for a lively, playful ride.
Vital Review

The Spire is Transition's newest, and biggest bike to date. Despite having less travel than the TR-11 (Transition's downhill bike), its wheelbase is longer. Numbers aside, Transition has billed this bike as more of an all-rounder and ready to party in the woods, as is the Bellingham brand's moniker. Was Transition able to perform some sort of wizardry and make those numbers shrink once on dirt? We couldn't wait to find out.


  • Rides like a smaller bike
  • Comfortable on the climbs
  • Lively trail manners
  • Spot-on build kit
  • Easy to get along with


  • Rides like a smaller bike
  • Rear suspension is harsh


  • Japanese Toray Carbon or Aluminum frame offerings
  • 29-inch wheels only (stock)
  • 170mm rear travel (160mm with 60mm stroke shock)
  • Size-specific chainstays
  • Lifetime warranty
  • 56mm upper and lower headset cups
  • Guided internal derailleur and dropper post routing (carbon)
  • External rear brake routing
  • Boost 148mm rear spacing
  • Threaded bottom bracket
  • Dual crown compatible
  • Price: $5,999 as tested

Our particular build features a carbon frame. The drivetrain is a SRAM GX Eagle 12-speed affair with SRAM Code RSC brakes. The Spire wins the big brake award for coming with a massive 220mm front rotor and 200mm rear. RockShox supplies suspension with its top-shelf ZEB Ultimate fork and Super Deluxe Ultimate rear shock. Schwalbe takes care of the tires with soft, Super Trail casing Big Betty and Magic Marys. Stan's Flow S1 wheels are a sensible choice for rims. Though we aren't doing a best bang-for-your-buck award for this review, the Spire definitely makes its case.

Transition offers the Spire in both a carbon and alloy frame with multiple build options. We applaud them for making a more affordable alloy frame on a brand new bike, we know there will be plenty of rippers needing to save some dollars to get on a bike like this.

Beyond the parts, the Spire is the slackest in this test. A 63-degree head angle in the high position is bested only by its 62.5-degree head angle in the low position. When paired to a 170mm fork, this would be a large contributor to the super-long 1257mm wheelbase, 15mm longer than the next bike. Our medium test bike had a 460mm reach, long but not the longest. This was paired to a size-specific 446mm chainstay length. Despite the long numbers, the Spire feels smaller on the climbs due to a 78.8-degree seat angle.

Putting the numbers aside, how was the Spire on the trail? Did our testers feel like they needed a CDL to turn this bike?

Rider Setup

Our testing team fussed with their settings during testing. The numbers below represent where they settled in the end.Compression clicks all started at the factory recommended settings and moved on from there. For simplicity sake, here are the highlight numbers that each tester used.

Casey Coffman

  • 5-foot, 9-inches
  • 180-pounds
  • Fork - 62psi, 3 tokens
  • Rear shock - 188psi
  • Front/Rear tire - 23psi, 25psi

Andrea Napoli

  • 5-foot, 8-inches
  • 140-pounds
  • Fork - 45psi, 1 token
  • Rear shock - 130psi
  • Front/Rear tire - 21psi/22psi

Ryan Lummis

  • 5-foot, 8-inches
  • 160-pounds
  • Fork - 60psi, 1 token
  • Rear shock - 160psi
  • Front/Rear tire - 25psi/28psi

Brad Howell

  • 5-foot, 9-inches
  • 165-pounds
  • Fork - 54psi, 3 tokens
  • Rear shock - 165psi
  • Front/Rear tire - 23psi/25psi

On the Trail

All four of our testers said the exact same thing - this is a 170 bike that rides like it has 150mm of travel. What did we all mean by this? Transition's Spire rides smaller than it is in both the handling traits and use of suspension travel. Of our test bikes, the Spire was deemed to be the most playful and eager to leave the ground. Despite being a very long and slack bike, the Spire is less of a handful than other bikes in this category.

While the wheelbase is long, the rider positioning isn't stretched out. This is because the Spire gets its length in the chainstays and slack head angle. This leaves a centered rider that has plenty of bike upon which to move about. The end result is a stable ride that is easily managed by not forcing the rider into a particular location. Let's not get it twisted though, the Spire is a long-legged 29er and has plenty of tractor-like capabilities.

Our team rode the Spire in both the low and high chip positions. Some of our test loop included some extremely steep and technical lines. Undoubtedly, getting the Spire as low, long and slack as possible helped deliver the utmost of confidence in this terrain. Transition would not have made such an option if it wasn't meant to be used, right? With a 220mm front rotor and meaty tires, Transition is sending a clear message of this bike's intent and we were hell-bent to get it there. We certainly appreciated the Spire's bold geometry as rocks came trundling down after us. It was no surprise that at these lower speeds, the Spire did take some decisive input to make it through tighter corners.

When the trail eased up a bit and was less about brake management, we could let the Spire run a bit more. We were very pleased with the Spire's ability to build speed so quickly. Again, this was all to be expected from such a large bike. What we were surprised by was how well the Spire kept its speed through more tame terrain. This is not a barge that needs constant fuel to stay on step, the Spire takes surprisingly little input to be a happy trail buddy.

Speaking of happy, our testers found the Spire to be an eager bike to play hookie and get into some bonus lines. There is no doubt the Transition pedigree of play is alive and well with the Spire. Our testers had a great time getting this bike airborne and using natural trail features to squeeze all the fun from the trail. That lively feel was not without its tradeoff though.

The flipside to such pop is a harsh feeling in rocky sections. The Spire rides quite stiff and transmits a lot of feedback to the rider. On smoother terrain, this translates nicely but on square-edged hits and rugged terrain, it can be exhausting. With particular respect to the rear end, the Spire has a harsh, almost bucking feeling on square-edged hits. Perhaps with more shock tuning, we could get some more compliance from the rear end but all of our riders had the same sensation.

Turning it back the other way, that same stiff ride makes for a bike that is perfectly happy on the climbs. Whether tractoring slowly up the grade or power-mashing, Transition did a nice job of making the Spire a compliant climber. Switchbacks did require more setup to clean but the Spire never felt floppy at the head tube nor did it want to loop out or lose traction.

Build Kit

Our Transition Spire was the second-cheapest bike in the test. However, it sported top-shelf suspension with all the bells and whistles. It also had Code RSC brakes, a massive leap in performance over the Code R models. In truth, we did not have one quibble about the parts on our test bike.

Our RockShox Zeb fork took some of our testers a bit of puzzling to get set up correctly. The Zeb is a buttery smooth fork but can come out of the box a bit too linear for steep, loose terrain. Initially, our testers felt it diving too much and added pressure to keep it higher in the travel. Ultimately, we were up to three tokens and back to recommended pressures. Having the ability to fine-tune compression with the Zeb Ultimate was a nice touch.

We were a little surprised that Transition was alone in outfitting the bike with a 220/200mm rotor combo from SRAM. These massive plates kept the speed demon in check and gave a boost to the Code RSC brakes. Other brands speccing SRAM brakes should take note.

Gearing can be a contentious topic. Some terrain is so darn steep and some rides are so darn long, riders need a break. Hear us out here. The Spire has a 30T front ring. We were constantly blowing through the cassette, rapidly changing gears to get the Spire up to speed. Additionally, even when sucking wind at 8,000-feet, we could not make use of those large Eagle cogs in the rear. A 32T ring would play much better to the crowd that will be reaching for this bike. Hammerheads may grab a 34T and super spinners may grab a 30T but the majority of mountain bikers would be better served with a moderate 32T ring.

We won't relegate the Spire to "flow" country but it absolutely dominates high-speed trails where maintaining your speed and boosting lips is job number one.

Test Session Take

Where you stand with the Spire is all about give and take. The same rough ride that beat us up in the boulders delivered pop and play on the other 80% of the ride. We'd add that while the Spire does ride like a smaller bike, it is still a 170mm travel 29er and does still make use of every inch of travel. Riders that want the extra security that comes with a bigger bike without the feeling of lugging it around are going to love the Spire. We won't relegate the Spire to "flow" country but it absolutely dominates high-speed trails where maintaining your speed and boosting lips is job number one.

Head here to catch the full 2021 Enduro Test Session Feature

Learn more about the Transition Spire, head to transitionbikes.com


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Transition Spire Carbon GX Bike
Model Year
Riding Type
Enduro / All-Mountain
Freeride / Bike Park
Sizes and Geometry
Wheel Size
Frame Material
Carbon Fiber
Frame Material Details
Full carbon fiber (front triangle, rear triangle, and rocker) made from Japanese Toray fiber with a tailored blend of 24T and 30T materials
Rear Travel
Rear Shock
RockShox Super Deluxe Ultimate Air, 205mm x 65mm
RockShox ZEB Ultimate, 44mm offset
Fork Travel
Head Tube Diameter
FSA. No.55R/57, 56mm/56mm press-in cups, zero stack
ANVL Mandrel Alloy 35, 800x20mm (S), 800x30mm (M-XL), 800x40mm (XXL)
ANVL Swage, 40mm
Sensus Lite
SRAM Code RSC with SRAM Centerline 220mm/200mm rotors
Brake Levers
Front Derailleur
Rear Derailleur
OneUp Components Bash Guide
SRAM GX Alloy DUB, 165mm
30 tooth
Bottom Bracket
73mm BSA threaded
SRAM XG-1275, 10-52 tooth
Stan's NoTubes Flow S1
Stan's NoTubes Neo Durasync
Sapim Race Double Butted
Front: Schwalbe Magic Mary, Super Trail, Soft, 29"x2.4"
Rear: Schwalbe Big Betty, Super Trail, Soft, 29"x2.4"
ANVL Forge Cromo
OneUp Components Dropper
Seatpost Diameter
Seatpost Clamp
37.0mm standard single bolt
Rear Dropout / Hub Dimensions
148x12mm Boost
Max. Tire Size
Bottle Cage Mounts
Huckleberry, Primer Grey

Geo adjust chip at the lower shock mount for high and low geometry settings

56mm/56mm press in headset cups are compatible with reach adjust headsets when used with a dual crown fork

Molded rubber frame protection on the downtube, chainstay, and seatstay

Fully guided internal dropper and rear derailleur cable routing in downtube and chainstay, external rear brake cable routing

GiddyUp suspension layout is tuned to work with both air and coil rear shocks

Enduro Max sealed bearings with bearing shields on main pivot

Stock 170mm rear travel with a 65mm stroke shock, optional 160mm rear travel with a 60mm stroke shock

27%-33% suggested sag range

SBG geometry and size-specific chainstays

SRAM UDH derailleur hanger

Accessory mount on underside of top tube

What do you think?
Where To Buy
Free shipping on orders over $50 (continental U.S. only).
International shipping available. Some exclusions apply.
Free shipping on orders over $50 (continental U.S. only).
International shipping available. Some exclusions apply.

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