Leva

CBW3: Alligt 20″ cargo bike wheel

157 days ago

4 minutes

Alligt has successfully tested the CBW3 wheel with the Grin modified all axel motor up to 125 kg static weight. See for the motor. (https://ebikes.ca/product-info/grin-products/all-axle-hub-motor.html) So CBW3 can have 125 kg static weight and the motor too. 

The CBW3 is a 406-35 mm injected moulded cargo bike wheel from PA6.6 with 60 % glassfibre.

This video from Grin, https://youtu.be/II1Z1T_EzU0, offers a quick overview of motor and wheel. If you are interested in this combination, you can contact Grin,  info@ebikes.ca. They will be happy to provide some pilot / beta customers with a system. Alligt will provide Grin with rims in May, whilst they are able to offer advice on the motor and controller and to possibly send interested contacts a complete wheel.

It is important to be aware of the fact that the Alligt wheels are less resistant to heavy impacts than steel rim wheels. The Alligt lightweight wheels are suitable for:

  • Vehicles with suspension;
  • Wheels with thick tires. Alligt has tested with the Schwalbe Pick-up 55-406 tire.
  • Use on a vehicle of which the driver has a correct understanding of the dimensions of the bike (not hitting pavement edges) 
  • The driver should also have a positive connection to the bike. The wheels are not suitable for rental bikes, if riders don’t get enough instructions for careful use in order to avoid misuse.

Why CBW3 can have less load than CBW2.

The static weight of 125 kg is less due to the shorter spokes, which give less elasticity compared to  CBW2 wheels, which can have 150 kg static weight.

Alligt started to test for 150 kg static weight end 2021. Unfortunately that did not work out well. We were surprised that a wheel with the same design stress parameters as CBW2 did not survive the drum with slate test in the same way. We tested it at 300 kg because we wanted to have a 100% safety margin. Then you get the 150 kg static weight, Alligt expected to test successfully.

After more than 10 wheels were tested till collapse on our drum with slate test machine with ±300 kg, we concluded that there was no other way than to test it at 250 kg and see if it would hold long enough. At a testload of 250 kg the wheel did not last long enough either. Consequently, we looked into small details of the product design and of the mould. We sanded some details in the mould to avoid sharp transitions. We tested several mould temperatures. We changed the after-pressure of the injection process.

Those three adaptations resulted in a product which is now constant and better. However, the conclusion is that the short spokes give the complete wheel less elasticity. The consequence is that the rim of CBW3, which is the same as the rim CBW2, will collapse at ±20 % less weight in this test. CBW2 can survive 300 kg on the test for more than 1500 km and CBW3 can survive that distance with 250 kg. At 300 kg CBW3 can have little more than 175 km.

Alligt also wishes to place the drum with slate test in the correct perspective. It is a test with “some” relation to the practice. On the road, Alligt’s plastic wheels (CBW1, CBW2 and likely CBW3) collapse sooner by a very heavy impact due to potholes or pavement edges than by a million relative small impacts or curves. The drum test is a reasonable test for fatigue and not for high impacts.

As a next step, we may add some test strips to the mould, so that every wheel gives one strip for a tension test and one strip for a kerf test. In the long run that will give extra information and is a more economic test than a drum test. Perhaps, Alligt will find a way to improve CBW3 to 150 kg some day.

Alligt also found how to interpret static calculation programs. The calculated stress for CBW3 at 300 kg was lower than for CBW2 at 300 kg.

Alligt hopes that some day they will be able to do a test of a wheel with a defined speed, suspension, tire and load to hit a defined pavement edge/ pothole. That will provide information to compare tires, material off wheels, kind of suspension etc. For all further details, contact Leo Visscher at Allight, Tel: +31 5727 852 41, Email: leovisscherkorver@gmail.com

Annick Roetynck

Annick is the Manager of LEVA-EU, with decades of experience in two-wheeled and light electric mobility.

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