The Fox Float X Factory sits in a useful part of the rear-shock range: enough adjustment to shape a serious trail bike’s handling, without making every ride a suspension experiment. On the Amflow PX Carbon Pro, it pairs a compact piggyback damper with an air spring and the familiar gold Kashima finish. It is a capable package, although the finish alone is not a reason to upgrade.
This assessment combines our Amflow PX Carbon Pro riding impressions with wider published testing and manufacturer specifications. The broader findings below are research, not additional riding claimed by Electric MTB UK.
Fox Float X Factory – 210 x 55mm
A premium air shock with useful support and straightforward external controls. Its performance depends on the frame and damper tune; the Amflow’s rear end reached its limits before its excellent fork.
At Tredz
MY2027 Float X Factory EVOL LV, 210 x 55mm, standard eyelet, manual 2-position lever; aftermarket tune, not Amflow-specific
+ Pros
- Low-speed compression and rebound controls
- Adjustable air spring and useful trail support
- Separate Open/Firm lever
− Cons
- No external high-speed damping adjustment
- Correct damper tune and frame clearance are essential
- Performance Elite offers the same adjustment features for less
Compare prices
MY2027 Float X Factory EVOL LV, 210 x 55mm, standard eyelet, manual 2-position lever; aftermarket tune, not Amflow-specific
Prices and availability may change. Prices last checked: 2026-10-20 11:01 UTC. Prices are checked when this guide is updated. Confirm the current price and availability with the retailer.
Our verdict
The Float X Factory is a convincing trail and all-mountain option when its tune matches the bike. Our Amflow experience supports a measured verdict: the rear suspension worked well within its limits, but had less reserve than longer-travel rivals. Published testing adds evidence of smooth mid-stroke movement and useful support. Confirm the exact generation, tune, mounting hardware and clearance before treating an aftermarket shock as a replacement.
Key specifications
- Type
- Piggyback air shock
- Reviewed bike
- Amflow PX Carbon Pro
- Original fitment
- 210 x 55mm, custom tune
- Rear-wheel travel on Amflow
- 150mm
- External damping
- Low-speed compression and rebound
- Lever
- Open / Firm
- Finish
- Kashima
- Retail comparison
- MY2027 standard-eyelet 210 x 55mm
- Sample weight
- Not measured
What is fitted to the Amflow?
Amflow specifies a custom-tuned, 210 x 55mm Float X Factory on the PX Carbon Pro. Those figures describe the shock’s eye-to-eye length and stroke; the bike delivers 150mm of rear-wheel travel through its linkage. They are not interchangeable measurements. The external controls provide low-speed compression, rebound and an Open/Firm lever.
It is also worth distinguishing this shock from the larger Float X2. The Float X is its own design, rather than an X2 with fewer knobs. Its appeal is a manageable set of adjustments for trail and all-mountain use.
Fox Float X Factory review: support and limits on the trail
In our complete-bike test, the Amflow’s rear suspension coped well up to a point, while the excellent fork left a particularly strong impression. As the ground became more demanding, the rear had less reserve than longer-travel rivals. That is a judgement about the complete bike: its travel, geometry, linkage and tune all contribute. It would be misleading to assign that difference entirely to the shock.
Broader testing gives the Float X a persuasive balance of movement and support. It can settle into its travel over broken ground without becoming vague when the rider loads the bike through a turn or pumps a compression. Earlier-generation tests also show why the base tune matters: changing an unsuitable compression tune made a substantial difference on one test frame. That is a compatibility lesson, not evidence that every Float X needs retuning.
Testing of the updated 2027 shock on a heavier electric mountain bike points to reassuring support during fast, hard impacts alongside useful compliance. Those results strengthen its case for eMTB use, but do not establish that an aftermarket version will improve this particular Amflow. There has been no controlled back-to-back comparison here.
Controls that are useful rather than overwhelming
Low-speed compression helps manage slower shaft movements associated with rider inputs, weight shifts and sustained loading. “Low-speed” refers to the damper shaft, not how quickly the bike is travelling. Rebound controls how quickly the suspension returns after compression. Together, these are practical adjustments for balancing support and recovery.
The separate Firm lever is convenient for smoother climbs and linking sections. It should not be treated as a guarantee of rigid lockout. Rough, loose climbs can favour the Open setting, where the rear wheel has more freedom to follow the surface. The absence of external high-speed compression adjustment keeps things simpler, but gives experienced riders one less way to change the response to sharp impacts.
Check the generation before buying
Fox’s 2027 Float X Factory receives a higher-flow main piston, revised valving and changes to the top-out and bottom-out bumpers. These are internal developments; a familiar-looking air can does not identify the model year. We have not confirmed the photographed shock’s generation from its identification code, so the retail card describes the current aftermarket product separately.
Start setup with the correct bike and shock guidance, wearing your usual riding kit. Establish sag and rebound before changing several settings at once. Air-volume spacers alter the spring’s progression; they are not a substitute for the right pressure or damper tune. Our eMTB suspension setup guide explains the foundations.
Value and alternatives
The verified current 210 x 55mm Factory offer is £699. That is a substantial spend, particularly if your existing shock is healthy and well matched to the bike. Performance Elite deserves consideration: Fox gives it the same damping and adjustment features, with a black anodised finish instead of Kashima. Gold coating alone does not establish a worthwhile performance gain.
RockShox’s Super Deluxe Ultimate D1 offers separate high- and low-speed compression adjustment, making it an alternative for riders who want more external control. The card below is a specification comparison, not a tested upgrade recommendation or confirmation of Amflow compatibility. Matching dimensions are only the first check; the tune, hardware and clearance also need approval.
RockShox Super Deluxe Ultimate D1
An alternative for riders who want separate high- and low-speed compression adjustment. Frame-specific fit and tune still come first.
Retailer offers are being checked.
RS-SDLX-ULT-D1; 210 x 55mm standard-eyelet specification comparison; exact tune and fit require confirmation
+ Pros
- Separate high- and low-speed compression controls
- LinearXL air spring
- 210 x 55mm option in the official range
− Cons
- No direct back-to-back test on our Amflow
- Exact 210 x 55mm retail stock not verified
- Hydraulic bottom-out specification varies
Why it makes the shortlist
Worth considering when high-speed compression adjustment matters to your riding. This is a researched alternative, not an approved Amflow replacement: confirm tune, mounting hardware and frame clearance with the bike manufacturer. No purchase offer is shown because matching retail stock has not been verified.
Key specifications
- Model
- RS-SDLX-ULT-D1
- Spring
- LinearXL air
- Damper
- RC2T
- Compression
- High-speed and low-speed adjustment
- Size discussed
- 210 x 55mm
- Claimed weight
- 530g at 210 x 55mm, without hardware
- Bottom-out
- Specification dependent
Verdict
The Float X Factory makes sense when you want useful trail support, an adjustable air spring and controls you can understand without spending every ride turning dials. The case is strongest as part of a well-matched complete bike. Its limitations are the price, the lack of external high-speed damping adjustment and the importance of getting the underlying tune right. On the Amflow, it is a credible part of a capable 150mm package; it does not give that bike the reserves of a longer-travel machine.
Frequently asked questions
Will any 210 x 55mm Float X fit the Amflow?
No. Confirm the mounting hardware, reservoir clearance and damper tune against the Amflow specification and manufacturer advice. Matching length and stroke alone is insufficient.
Is Factory worth more than Performance Elite?
Not automatically. The shared damping and adjustment features make Performance Elite a sensible value comparison. Choose Factory because the complete specification and price suit you, rather than assuming Kashima changes the whole ride.
Is this a replacement for a Float X2?
Not by default. They are different shock platforms. Any replacement needs to suit the frame, travel, intended riding and tune, rather than simply carrying the Fox name.