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Soundsystem Bike Trailer Plans
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bike-trailer.md

DIY Ride‑&‑Party Rear‑Firing Sound‑Trailer

(Wike DIY Cargo Trailer · 2 × DFB subs · 2 × SOUNDBOKS 4 tops) Built for safe, nimble riding and instant full‑height PA playback once you park.

0  |  At‑a‑Glance Load Specs

Component Foot‑print (W × D) Height Unit Wt
DFB Sub 61.7 × 49.5 cm 27.4 cm 15.5 kg
SOUNDBOKS 4 43 × 32 cm 65 cm 16.1 kg

Deck 125 × 70 cm • Axle line 50 cm fwd of rear edge • Gross mass ≈ 69 kg Target tongue‑weight = 5 – 10 kg (lift: feels like a loaded pannier)

1  |  Bill of Materials

Group Item / Spec Cut / Size Qty
Base Kit Wike DIY Cargo Trailer (wheels + axle + hitch) — 1
Frame Tube 25 × 25 mm 6061‑T6 square aluminium tube 2 × 125 cm · 2 × 70 cm · 3 × 65 cm 7
Deck 9 mm marine birch ply (6 mm honeycomb Alu opt.) 125 × 70 cm 1
Fasteners M6 × 16 SS bolts + nyloc nuts (frame) 36 —
SS self‑tapping screws (deck) 20 —
Tie‑downs Cam straps – 1 × 225 cm (long) · 2 × 180 cm (X) — 3
Recessed SS D‑rings (≥ 400 lb) — 6
Isolation 10 mm EVA foam pads 2 × 62 × 50 cm 2
Pole cups 35 mm flush‑mount speaker sockets — 2
Finish Spar urethane (ply) or epoxy + bed‑liner (Alu) — —
Options 36‑spoke BMX wheels (14 mm) • 70 mm drum‑hub wheel — 2

2  |  Tools Check‑List

Mitre saw / hacksaw • deburr tool • drill (5 & 6 mm bits) • rivnut gun / M6 tap • metric hex keys • 10 mm wrench • small torque wrench • square • tape • pencil • Loctite Blue.

3  |  Frame Geometry

              125 cm deck
FRONT  → ┌──────────────────────────┐
         │                          │ 10 cm to 1st brace
         │                          │
         │          ⬤ axle ⬤      │ 50 cm to axle brace
         │                          │
         │                          │ 10 cm to rear brace
REAR  ←  └──────────────────────────┘
                 70 cm

⬤ axle brace bolts to Wike plates.

4  |  Frame Fabrication

  1. Cut & deburr seven tube lengths.
  2. Dry‑fit with Wike corner blocks; square frame.
  3. Drill 6 mm through all joins; bolt with M6 SS + nylocs.
  4. Bolt axle plates to centre brace; torque to spec.
  5. Attach tow‑bar left‑front; clip safety lanyard.

5  |  Deck, Pads & Poles

  1. Seal ply (2 × spar urethane).
  2. Pre‑drill & screw deck to frame.
  3. Glue EVA pads at 25 cm & 50 cm marks from front edge (centre W‑axis).
  4. (Opt.) Hole‑saw 35 mm pole cups 210 mm forward of each pad; fix with M6 bolts.

6  |  Running Gear

Fit kit 20 ″ wheels (outside width ≈ 98 cm). Optional: BMX 14 mm wheels + drum‑hub brake for hills.

7  |  Speaker Layouts

7.1 Ride‑Mode (low C‑of‑G best manoeuvrability)

FRONT  (tow‑bar) →
┌────────── 125 cm ──────────┐
│ ■ Sub‑1  gap  ■ Sub‑2      │
│ ▣ SB4‑1 flat  ▣ SB4‑2 flat │ 70 cm
└────────────────────────────┘
REAR  (sound exits)

Legend: ■ DFB sub (woofer rear) ▣ SOUNDBOKS 4 laid flat (grille up). C‑of‑G ≈ 53.5 cm from rear → tongue 5–9 kg.

7.2 Party‑Stop Mode (full projection when parked)

           ┌────────── 125 cm ──────────┐
           │ ■ Sub‑1   gap   ■ Sub‑2    │
           │  ↑││↑              ↑││↑    │   tops upright
(pole) T   │ ▣ SB‑1            ▣ SB‑2   │
           └────────────────────────────┘

(Opt.) drop 60 cm poles into cups, then angle tops ↓10 °.

8  |  Strap Routing

SIDE ELEVATION (ride‑mode)
  long cam strap
     ↓
┌─────────▣▣─────────┐
│        /  \        │   X‑strap L
│  ■────/    \────■  │
└─────────▣▣─────────┘
   rear            front

Long strap over tops hooks to forward & rear D‑rings. Two X‑straps loop diagonally around each stack to side D‑rings. Tighten until EVA pads compress ≈ 1 mm.

9  |  Tongue‑Weight Tuning

 SIDE PROFILE
  C‑of‑G tops flat  ▼
                    ▓▓  53.5 cm
┌──────────────────────────────┐  deck
        ▲ towing eye

Slide both stacks together ± 2–3 cm until the tow‑bar lifts with 5–10 kg force.

10  |  Lighting & Safety

Purpose Device (battery) Mount
Rear safety USB‑C 300 lm tail rear rail
Side vis Amber spoke pods wheel spokes
Edge glow RGB rope (3 × C) deck rim
Under‑glow RGB strip (4 × AA) underside rails
Party accent 2 × USB‑RGB bars cross‑brace
Sound reactive DJ puck deck centre
Work light USB‑C motion bar tow‑bar

Nightly charge: all USB on 6‑port hub; swap AA/C each season.

11  |  Finishing Touches

30 mm Alu side‑rails (pop‑riveted) • high‑viz reflectors • 600 D roll‑up rain cover (95 cm clear) • phone/email engraving • whistle‑stop backup strap at hitch.

12  |  Maintenance Schedule

Task 10 km 100 km
Re‑torque M6 hardware ✔︎ ✔︎
True wheels & spokes — ✔︎
Lube push‑button axles — ✔︎
Refresh deck coating — Yearly

13  |  Pre‑Ride Checklist (60 s)

☑  Tongue weight feels 5–10 kg
☑  Straps tight, D‑rings closed
☑  Tail‑light flashing
☑  Quick pink‑noise balance check
☑  Hitch pin & wheel nuts secure

Roll, Flip, Party!

With Ride‑mode tops flat you carve turns safely; in 30 s you pop to Party‑stop for crystal highs over the crowd. Balance, strap, light, then let the bass chase you down the street.

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