For Vehicles
Tow-Bar Mounted Bike Racks
Modular 1-4 bike racks manufactured in Australia for cars, SUVs, 4WDs and utes.
Four Bike Rack Conversion Pack
From $815.00
Ships in 3–5 business days
·
Made in Melbourne
Easily convert your modular 2-Bike Rack to a 4-Bike and back again in seconds with the iSi Conversion Pack. Each pack includes a separate main beam and shares modular components to swap between your racks.
Modular Expansion · 2 to 4 Bikes
Two Today. Four Tomorrow.
The iSi Conversion Pack turns your existing two-bike carrier into a four-bike carrier and back again in seconds. A dedicated four-bike main beam keeps both configurations at full strength, while modular components transfer between the two beams as needed. One system that scales with the ride, from solo weekenders to family holidays.
Swap In Seconds
Dedicated 4-Bike Beam
Vehicle + Caravan Compatible
Lifetime Warranty
How It Works
Transfer. Swap. Ride.
Your modular components (wheel cradles, frame supports, Tee-Handles) transfer between the two-bike and four-bike main beams. The Conversion Pack provides the dedicated four-bike beam and the additional components needed for two extra bikes.
1
Remove 2-Bike Beam
Lift the two-bike main beam off the pivot base using the tool-free pivot pins. The beam separates from the mount in seconds.
2
Transfer Components
Move your existing wheel cradles, frame supports and Tee-Handles across to the four-bike beam. Add the additional components from the Conversion Pack for bikes three and four.
3
Drop In 4-Bike Beam
Drop the four-bike beam onto the same pivot base. Secure with pivot pins. You're now carrying four bikes on the same mount system.
"Unlike racks that split a four-bike frame in half, the iSi system uses a dedicated beam for each configuration. Both the two-bike and four-bike setups remain at full structural strength."
Why A Dedicated Beam
Full Strength. No Compromise.
Some systems try to split a four-bike rack in half to create a two-bike option. That compromises strength, adds weight, and introduces weak points at the join. The iSi approach is different.
Engineered Modularity
Two Beams. Zero Weak Points.
Each beam is a single-piece structural member manufactured from Australian high-strength steel. There are no joints, no split points and no bolted connections in the load path. When you're running the two-bike beam, it's a complete two-bike carrier. When you're running the four-bike beam, it's a complete four-bike carrier. Both maintain the iSi lifetime warranty.
- Dedicated single-piece beam per configuration
- No split joints or bolted connections in the load path
- Both beams covered by the iSi lifetime warranty
- Rated for on-road and extreme off-road conditions
What's Included
In The Conversion Pack
Everything you need to expand from two bikes to four. Your existing pivot base, wheel cradles and frame supports transfer from the two-bike beam.
Dedicated 4-Bike Main Beam25° departure clearance with your selected carrier length
Both Horizontal Wheel Support BeamsFor the four-bike configuration
All Main Beam HardwarePivot pins, fasteners, everything required
Additional Wheel + Frame ComponentsExtra cradles and supports for bikes three and four
Choose Your Length
Two Lengths. One Beam Angle.
Select the beam length that matches your setup. Both options use 25° departure clearance for medium ground clearance applications.
750mm
CompactShorter overall length for tighter vehicle clearances
850mm
ExtendedAdditional length for wider handlebar and saddle clearance
One System For Every Ride
Conversion Pack Key Features
Swap In Seconds
Transfer components between the two beams and swap the beam on the pivot base. No tools required for the beam swap itself.
Vehicle + Caravan
Compatible with all iSi pivot base tow bar systems and caravan drawbar mount systems. The same conversion pack works on both.
Full Lifetime Warranty
Both the two-bike and four-bike configurations are covered by the iSi lifetime warranty. No reduced coverage for the conversion setup.
84kg Total Load
The four-bike configuration supports up to 84kg total load. Up to 32kg per bike and 16kg per wheel. Rated for on-road and off-road.
Lifetime
Warranty
84kg
Total Load (4-Bike)
Made In
Melbourne
30 Day
Returns
Not sure which length you need?
Tell us your vehicle, your existing two-bike carrier model and the bikes you plan to carry. Our team will confirm the correct Conversion Pack configuration.
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| Specifications | Two Bicycle Carrier | Four Bicycle Carrier | Drawbar Mount Systems | Vehicle Mount Systems |
|---|---|---|---|---|
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 |
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|
| Weight | 14.15kg | 25.75kg | 9.80kg – 21.20kg | 4.80kg – 6.30kg |
| Bicycle Capacity | 1- 2 Bicycles | 1 – 4 Bicycles | – | – |
| Weight Capacity |
64kg Total Load Up to 32kg per bicycle Up to 16kg per wheel |
84kg Total Load Up to 32kg per bicycle Up to 16kg per wheel |
– | – |
| iSi Modular Component | Drawbar Mount Compatible ☑
Vehicle Mount Compatible ☑ |
Drawbar Mount Compatible ☑
Vehicle Mount Compatible ☑ |
Two and Four Bicycle Carrier Compatible ☑ | Two and Four Bicycle Carrier Compatible ☑ |
| Pivot Function | ☑ | ☑ | Pivot Up & Over | Pivot down to the ground |
| No Straps or Tie Downs | ☑ | ☑ | ☑ | ☑ |
| Light Board Compatible | ☑ | ☑ | ☑ | ☑ |
| Carbon Safe | ☑ | ☑ | ☑ | ☑ |
| Rating | On–Road + Off–Road | On–Road + Off–Road | On–Road + Off–Road | On–Road + Off–Road |
| Materials | 100% Australian Made with 100% Australian steels | 100% Australian Made with 100% Australian steels | 100% Australian Made with 100% Australian steels | 100% Australian Made with 100% Australian steels |
| Warranty | Lifetime Warranty | Lifetime Warranty | Lifetime Warranty | Lifetime Warranty |
| Buyback Program | ☑ | ☑ | ☑ | ☑ |
Frame Support Cradles
iSi Frame Support Cradles are designed to keep the bicycle upright while all transport loads are handled through the Four Point Wheel Cradles. Manufactured from solid steel rod, they resist high-frequency vibrations over corrugated roads. A proprietary rubber compound developed in house features a wide, soft, and UV-resistant rubber. The result is unmatched protection for even the most delicate carbon, titanium, or thin-wall alloy frames.
Main Beam
The main beam is the structural backbone of the iSi carrier and is available in both 25° and 40° departure angle configurations at various lengths. With bikes staggered vertically along the beam, this stadium-style layout reduces the rack’s overall length by managing hub-to-hub clearance. This results in the most compact rack profile on the market, minimising rear overhang on the vehicle.
The staggered positioning also provides a clear working field for loading and unloading bikes with no overlapping handlebars or awkward reach-arounds. Designed for 2- or 4-bike configurations, the main beam connects tool-free to the pivot base and can be quickly swapped to a trailer or removed as needed. It’s a rigid, modular foundation that delivers both performance and practicality for serious adventure travel.
Tow Bar Pivot Base Mounts
The iSi Pivot Base is a robust modular hitch mount that comes standard with a high-tensile anti-rattle hitch stabiliser and an integrated auxiliary license plate holder (or optional lightboard). It’s offered in multiple height and length configurations for the best compatibility for different towbar depths and clearances for drop-down tailgates or rear swing out doors. Moreover, the modular mounts provide ample departure clearance so your bikes or rack avoid ground strikes. The design also features adjustable mounting positions (with multiple hitch pin holes) for fine-tuning the rack’s position relative to your vehicle, yielding a perfect fit tight to the vehicle while providing and secure wobble-free performance.
Adjustable Quad Contact Wheel Cradles
Each bike is stabilised and secured via our Quad Contact Wheel Cradle system with no clamps, bungees, or tie-downs required. The mandrel bent hoops support the tyre at four points on the tread, locking the bike in position through the wheels. This eliminates any unwanted bike movement or rolling left and right as you travel especially over corrugations or off-road tracks. Each cradle is mounted on a sliding offset sleeve, allowing independent height adjustment to finely control handlebar and saddle clearance. Bikes sit tighter and more securely with a narrower footprint, creating a compact, stable load without compromising ease of loading.
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