We invented the filament wound carbon rim.
Venn rims come from wind tunnels, supercomputers and a winding machine that places every fibre where the design says it goes. Here is the work behind them, and the numbers you can check.
In the wind tunnel: smoke and laser trace the airflow over a Velocite bike
- 2015The first filament wound bicycle rims, and a Eurobike Award
- 10Industry awards, from juries in Germany, Belgium and Taiwan
- 150JImpact pass mark for downhill rims; 100 J for road, gravel and XC. The UCI requires 40 J
- 5yearsWarranty on every Venn rim
Recognition
10 awards since 2008Juries in Germany, Belgium and Taiwan have recognised our work for design, innovation and manufacturing technology. The composites industry invited us to show it.
Filament wound carbon rims
For winding continuous fibre around the rim profile instead of laying up cut sheets by hand. A first for bicycle rims.
Venn Rev 35
The same rims won at Asia’s largest bicycle show, the year they launched.
Venn Rev 35
Taiwan’s leading design award, for the rim that started the filament winding era.
Start-up Innovation Award
The first award of its kind, presented at Velofollies in Kortrijk, for Venn filament wound rims.
Velocite Helios Aero
The aero frame that won the combined iF Design and Taipei Cycle d&i award in the bicycle category.
National Entrepreneurship Award
One of ten, chosen from 80 applicants, followed by the Taiwan Excellent Enterprise Quality Award in 2011.
Invited by the composites industry
At JEC Asia 2019 the JEC Group highlighted Velocite for its pioneering work in composite processing. Victor Major spoke on the advance of thermoplastic composites and the questions the industry has to answer: scaling production volume and making structures recyclable.
Research that ends up in the rim
Every Venn rim starts as an engineering question, not a styling exercise. We work with universities, research centres and material makers, and the results go straight into the laminate.
Fibre chosen for its job
- Toray T1100Ultra-high-strength fibre, now in our newest rim laminates
- Toray T800The main structure: high strength and stiffness
- Toray T700SWhere toughness and impact resistance count
- High modulusStiffness where it is needed, without the weight
Aerodynamics, computed and then measured
We design our own profiles with computational fluid dynamics, then prove them in the wind tunnel. Bicycle brands large and small, and OEM rim factories, have used the same work for their own products.
- Designed for the riderHandling in a crosswind matters as much as drag in a straight line.
- Profiles for each disciplineRoad, gravel and mountain rims each get a shape that suits the tyre and the speed.
- Checked in the wind tunnelSimulation first, then measurement on real wheels.
Effectively zero lift, in every condition
The Var 507 was never about the lowest drag figure in one wind tunnel setting. Its profile puts the aerodynamic centre just behind the axle, so gusts and passing traffic send effectively no feedback to the handlebars.
The first rim profile designed by an algorithm
With National Cheng Kung University, a genetic algorithm driving a CFD solver generated 675 profiles. We fixed only the tyre (25 mm), the depth (77 mm) and the widest point (30 mm; without that limit the optimum was 42 mm wide). The shape itself was left free. Concave and bulbous candidates stayed in the search untouched, and had one of them been fastest, we would have made it. The leading candidates were then built in 3D and simulated as whole wheels, and the best became the mould. No bicycle rim had been designed that way before.
1k filament winding
Fifth generation of the process we started in 2015A machine lays continuous 1k carbon tow exactly where the laminate design puts it, on every rim, every shift. Hand layup can be excellent, but not the same every time.
- The same rim, every timeA machine doesn’t tire, lose focus or judge an error “close enough”.
- Exact resin contentTowpreg arrives pre-impregnated, so every wrap carries the same resin.
- Better compactionNarrow tows leave channels for gas to escape during curing: fewer voids.
- Nothing to hideOur matte and gloss finishes are the moulded surface, with no clear coat over it.
Why 1k
Wider tape is quicker to wind and cheaper to buy. Narrow 1k tow gives finer control of where fibre goes and how much, so material sits where the load is. It is slower and costs more. For a rim that has to be round, true and consistent, it is worth it.
Moulded spoke holes, no cut fibre
On the Venn 420, 520, 440, 540 and 620A TCD UL the spoke holes are moulded in, angled to the hub flange, not drilled after curing. The fibres run round each hole instead of ending at it.
Every listing’s specifications give the ERD, hole options and dimensions you need to build.
Quality control, with the numbers
Every Venn rim model goes through the same test programme before it is sold. The only thing that changes is how hard we hit it.
The rest of the programme, with results
From the Venn 520 TCD UL wheelset test pack, as an example:
| Test | Result |
|---|---|
| Fatigue | 596 km on the rig, about 1,000,000 cycles: no cracks, bulges or spoke detachment |
| Riding run-out | 4 hours and 130 km of continuous running: rear wheel run-out within 0.1 mm |
| Spoke hole strength | Every hole above the 150 kgf pass level |
| Lateral rigidity | 133 N/mm |
| Tyre retention | 120 psi held for 8 hours, flatness and deformation within limits |
| Heat | 110 psi at 80 °C: rim width changed by 0.05 mm |
| Build | Flatness 0.15 to 0.18 mm, roundness 0.20 to 0.22 mm, before and after tubeless inflation to 120 psi |
- Gravel tooA Venn 440 TCD UL measured 0.18 mm flatness and 0.19 mm roundness, and deflected under 4 mm at 5 kg lateral load against a 5 mm limit.
- Backed by a 5-year rim warrantyAnd 2 years on complete wheels.
Rim brake rims that take the heat
Our rim brake models use a custom high glass transition (Tg) resin. It keeps its stiffness well beyond what hard braking on a long descent normally produces, with good pads and well-adjusted brakes.
- about 216 °CStorage modulus onset: where stiffness starts to fall
- about 236 °CLoss modulus peak
- about 240 °CTan delta peak, the figure usually quoted as Tg
Rims engineered from first principles.
Choose your rim, or talk to us about wheels and OEM projects. Complete Venn wheelsets are at vennwheels.com.