Two rigs sit next to each other. Same colour, same seat, same wheelbase. One feels like a race car. The other creaks the moment you brake hard. The difference usually sits in one number: the size of the aluminium profile.
Profile size decides how much force the frame absorbs before it starts to move. It also decides how far you upgrade later. So before you compare prices, compare millimetres. That single choice shapes every lap you drive afterwards.
What do 40 x 40, 40 x 80, 40 x 120 and 40 x 160 mm actually mean?
An aluminium profile is an extruded beam with slots on every side. The two numbers describe the cross section in millimetres. A 40 x 40 mm beam measures four centimetres by four centimetres. A 40 x 160 mm beam keeps the same width but grows four times deeper.
That depth matters more than the weight of the metal. Stiffness against bending rises steeply as a beam gets deeper in the direction of the load. Double the depth and the beam resists bending many times better. Racers feel that difference instantly through the steering wheel.
The slots also give the frame its second job. Every slot accepts a T nut, so brackets, pedal decks, monitor arms and shifter arms slide anywhere along the beam. A wider profile simply offers more mounting surface for those brackets.
SIMGASM | Hobby Aluminum Sim Racing Cockpit - Black
Why does a deeper profile handle force feedback better?
A direct drive wheelbase twists the mounting plate every time the front tyres load up. Modern units deliver anywhere from 5 Nm to well past 20 Nm, and a mid range unit such as the Simagic Alpha EVO 12 Nm wheelbase already sits in that upper half. That torque travels straight into the frame. A thin beam flexes a fraction of a millimetre, and that fraction eats the small texture in the force feedback signal.
You notice it as vagueness. Kerbs feel soft, the front end feels late, and you correct slides a beat too slowly. Our guide to direct drive torque in Nm explains how much force each class of wheelbase actually produces.
Braking pushes where steering twists
Load cell pedals measure pressure, not travel. A committed racer presses 60 to 90 kg through the brake pedal, and hydraulic sets go higher still. That load hits the pedal deck as a straight push, so the deck and its supporting beams need real depth.
This is why SIMGASM publishes a rated braking load per tier. The Hobby carries 150 kg at the pedal deck, the Club steps up to 200 kg, and both the Sport and the Pro reach 300 kg. Match that figure to your pedal set and your leg strength.
Which profile size fits your wheelbase?
Start with torque, then add your braking style. A 3 to 8 Nm base on a 40 x 40 mm frame works well for a first dedicated simulator. The SIMGASM Hobby fills that role and takes wheelbases up to 16 Nm.
Around 9 to 15 Nm, a 40 x 80 mm main profile gives noticeably more reserve. That is the Club tier, and it suits a setup that keeps growing. Once you run 15 Nm or more with load cell pedals, move to 40 x 120 mm or 40 x 160 mm.
SIMGASM | Club Aluminum Sim Racing Cockpit - Black
What changes between the Sport and the Pro?
Both tiers share the same rated braking load, the same integrated cable routing and the same motion ready construction. The Pro grows the main profile from 40 x 120 mm to 40 x 160 mm and adds heavy duty steel reinforcement at the critical mounting points.
So the Pro exists for structural headroom rather than for extra features. Pick it when you plan a 20 Nm or 25 Nm base, hydraulic pedals, triple screens and a motion platform on one frame. Pick the Sport when you want that behaviour in a slightly tighter footprint.
The numbers make the gap concrete. A Hobby frame weighs 20.5 kg and measures 500 x 1270 x 580 mm. A Sport frame weighs 38.94 kg and measures 580 x 1320 x 720 mm. Mass and depth arrive together, and both feed stability.
Does a bigger profile always drive better?
No. A frame only helps up to the point where it stops moving. Once your rig sits still under maximum braking and maximum torque, extra aluminium adds weight, cost and floor space rather than lap time.
Room size also decides. A deeper profile raises the height of the pedal deck and the wheel deck slightly, and it eats a few centimetres of length. Check your space first, because a rig that blocks a door frustrates you every week.
Material choice sits alongside profile size. Our comparison of aluminium versus steel sim racing cockpits explains why extruded aluminium wins on adjustability while steel tubing wins on price.
SIMGASM | Sport Aluminum Sim Racing Cockpit - Black
How do the four SIMGASM tiers line up?
SIMGASM builds one architecture in four depths. Hobby uses 40 x 40 mm, Club uses 40 x 80 mm, the Sport range uses 40 x 120 mm and the Pro range uses 40 x 160 mm. Every tier accepts the same accessory range, so an upgrade never means starting again.
Each tier also offers four wheel mount variants: Bottom Mount, Front Mount, Side Mount and Asetek Front Mount. You choose the chassis for its depth, then pick the mount that matches your specific wheelbase model.
Ready to compare the four depths side by side? Browse the full range of aluminium sim racing rigs, or open the wider sim racing cockpit collection to see every finish.
Q&A
We answer a few questions that come up often:
Is 40 x 40 mm strong enough for a direct drive wheelbase?
Yes, within limits. A 40 x 40 mm frame such as the SIMGASM Hobby handles wheelbases up to 16 Nm and a rated braking load of 150 kg at the pedal deck. Beyond those figures, step up a tier.
What does 8020 aluminium mean?
8020 refers to the modular T slot extrusion system that most premium rigs use. The profiles carry slots on every face, so brackets clamp anywhere along the beam. Sizes such as 40 x 40 mm and 40 x 80 mm belong to the same family.
Does a deeper profile make the rig heavier to move?
It does. A 40 x 120 mm chassis roughly doubles the weight of a 40 x 40 mm chassis. Add a caster wheel set when you want to roll the rig aside after a session.
Do all profile sizes take the same accessories?
Across the SIMGASM range, yes. Monitor stands, chassis extensions, shifter arms and wheel mounts fit every tier, which keeps the upgrade path open.
Which profile size suits triple monitors?
Any tier accepts a monitor stand, but three large screens add leverage and mass. A 40 x 120 mm or 40 x 160 mm frame keeps that weight steady during heavy braking.
Should I buy a bigger profile than I need right now?
Only when a stronger wheelbase or a motion platform already sits in your plan. Otherwise the money buys more lap time in pedals and a proper seat.
Want to learn more? The experts at SIMGASM will be happy to help you.
