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Digital gravel design study2026 / 45°46′N

A//45 玉龍 / YÙLÓNG

Find the
fast line.

An original race-inspired gravel concept exploring flow, force and control across broken ground. Calm speed on the 700x45 line.

Explore A//45 ↓View full spec
7.8 kg · target mass45 mm · 700x45 design envelope460% gear range

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01 / 玉龍 · YULONG

Made to
move like water.

The A//45 reference geometry uses a 1,038 mm wheelbase, approximately 61 mm unloaded trail and a 75 mm bottom-bracket drop.

61mm
trail

02 / Carbon architecture

Shaped for
the rough.

Proposed carbon construction wears a deep jade lacquer, a cinnabar dragon panel and flush champagne-gold transfers. Frame and fork provenance depends on which model channel is loaded; the strip at the top of the page names it. The down-tube storage cover is a separate solid; the hatch is a cut in the frame envelope.

01 Down-tube storage pocket · down_tube_storage_cover
02 T47 threaded serviceability intent

03 / Useful velocity

Fast is a
state of calm.

This camera isolates the fork-crown and stay/tire corridors that the 700x45 design envelope must clear. The packaging CAD keep-outs are front_tire_keepout_700x45 and rear_tire_keepout_700x45; the interference matrix is the numerical evidence.

45mm
700x45 design envelope

04 / RED XPLR AXS

One ring.
Every horizon.

A 42T crank meets SRAM’s 10–46T XPLR cassette: thirteen closely judged decisions and a 460% range. The UDH Full Mount dropout is modelled from SRAM’s rev H.14 interface spec and runs clear in the packaging CAD; the derailleur’s own body-and-pulley sweep is not modelled yet, and the transmission you see is a visual model.

1×13wireless
shifting

05 / Total system grip

Grip is
speed.

Zipp documents the 303 XPLR SW around a 32 mm internal rim, paired here with Goodyear XPLR Inter 45s. Those are the supplier figures; the rim and casing in the render are visual models built around them, not supplier CAD.

32mm
internal rim

06 / Command center

Eyes up.
Elbows free.

A YULONG one-piece bar/stem shell — not a bolt-on bar and stem — targets a familiar 42 cm hood position opening into 5° of flare. The shell and its controls are visual models; the concealed hose path remains a proposed, serviceability-gated interface.

70 mm reach
115 mm compact drop

07 / 龍色 · YULONG finishes

Myth, in motion.

Jade for vitality. Cinnabar for heat. Gold tracing the emblem’s path. Choose your expression.

Selected finish: Yù

08 / Numbers, not noise

Specification.

Illustrative component build around the packaging CAD. Supplier documentation supports component selection; provenance marks say how each number was sourced.

Evidence state · calculated · unreleased — no revision is under configuration control

What stands behind each row
  • packaging CADClosed by the parametric packaging CAD baseline.
  • calculatedArithmetic from figures already on this page.
  • supplier specPublished manufacturer documentation for the named part.
  • selectionA component or interface standard we have chosen, nothing more.
  • visual modelThe part you see in the render is a stand-in mesh — an adapted bought-in donor or a YULONG-authored shell — not the named product's geometry.
  • target · unvalidatedA design target. No analysis, prototype or measurement supports it yet.
Platform+
Proposed frame
Carbon composite · laminate and process not releasedtarget · unvalidated
Mass intent
≈1.0 kg frame / ≈0.45 kg fork · no laminate or mass model exists yettarget · unvalidated
Tire envelope
700x45 design envelope · CAD keep-outs front_tire_keepout_700x45 / rear_tire_keepout_700x45 · 6 mm radial / 4 mm lateral allowance is an assumptionpackaging CAD
Axles
12 × 100 / 12 × 142 mmselection
Bottom bracket
T47-85.5 Road Wideselection
Proposed utility
Down-tube storage pocket with removable cover · bottle-boss keep-outs modelled · top-tube and fork mounts not modelledpackaging CADtarget · unvalidated
Drivetrain+
Groupset
SRAM RED XPLR AXS E1, wireless 1 × 13selection
Crank
42T chainring and crank sweep cleared in packaging CAD to SRAM's rev J fit spec · 170 mm arm length and power meter not modelledpackaging CADvisual modeltarget · unvalidated
Cassette
XG-1391, 10–46T, XDRsupplier specvisual model
Range
460% · 4.20 high / 0.91 lowcalculated
Controls
Wireless drop-bar hydraulic controls · RED AXS HRD is the intended tierselectionvisual model
Rotors
160 / 160 mm · Paceline X is the intended rotorsupplier specvisual model
Derailleur mount
UDH Full Mount · frame interface modelled from SRAM 90-7518-190-000 rev H.14 · backward stop designed; derailleur body/pulley sweep is not modelled yetpackaging CADtarget · unvalidated
Rolling stock+
Wheels
Zipp 303 XPLR SW · 1,452 gsupplier specvisual model
Rim
54 mm deep · 32 mm internal · hooklesssupplier specvisual model
Tires
Goodyear XPLR Inter 700 × 45 TLR · 45-622 is the recorded 700x45 design envelopesupplier specvisual model
Wheel limit
135 kg · wheel-manufacturer limit, not complete-bike ratingsupplier spec
Component ceiling
43 psi · wheel/tire documentation; bike recommendation TBDsupplier spec
Contact+
Cockpit
YULONG one-piece bar/stem shell · concealed routing · no separate stemvisual modeltarget · unvalidated
Cockpit reach
92 mm to bar centre · the figure the cockpit-junction build gate enforces · no cockpit geometry exists in the packaging CADtarget · unvalidated
Bar shape
42 cm · 70 mm reach · 115 mm drop · 5° flaretarget · unvalidated
Seatpost
27.2 mm bore · zero offset · YULONG-authored postpackaging CADvisual model
Saddle
Gravel saddle · 142 mm as depicted · 150 mm remains the intentvisual modeltarget · unvalidated

Provisional size M reference

Race instinct.
Gravel manners.

Reference geometry shown in millimetres — outer envelopes with a packaging-offset inner, plus the down-tube pocket region. This table is the datum. Rider fit, manufacturing tolerances and handling remain subject to engineering and physical prototype validation.

Stack575
Reach395
Head angle71.5°
Seat angle73.5°
Wheelbase1,038
Chainstay425
BB drop75
Trail≈61

玉龍 Digital study / YULONG studio

Choose
your line.

A//45 is drawn for the fast line — 1×13 range, 700x45 calm, and a carbon architecture in jade, cinnabar and gold.

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