We have been wanting to make a Quad option for the Catrikes for a long time. The Quad platform gives you the maximum utility, traction, and stability. The Quad platform allows the easy adaptation to power assist and can convert the tadpole trike into a true pedal car. There are several special considerations I have focused on while creating a Quad Conversion for the Catrike. 1. The Quad Conversion should be a high-performance solution. This means that the conversion should enhance the performance of the Catrike without detracting from it. Lightweight and performance oriented. 2. The rigid aluminum Catrike frame needs to be isolated somewhat from the rear axle to prevent undue stress. While the isolation method will act as a suspension, the main focus is road handling and tolerances will reflect that instead of off-road. 3. The stock wheel mounting position should be used to mount the middrive. There are several benefits to doing this. The stock chain line can be used and strength is added to the wheelstay area. 4. Stock derailleur hanger should be used. Keeping the derailleur hanger allows us to maintain the adjustability of the boom. It also allows us to use a standard cassette and derailleur for a lower-cost and high-efficiency middrive. 5. Use a wide range of middrives. While I want to keep the axle as close as possible to the dropouts (to minimize leverage against the stock dropouts) I want to allow enough room to be able to use the larger options like the Nuvinci or BionX electric solutions. 6. The rear axle assembly should have provisions for brakes and fenders. 7. The Quad Conversion should use the stock (or Catrike-compatible) hubs and wheels on the back to allow for a consistent look and easy availability. 8. The Quad Conversion should fit as many Catrike models as possible. All models with the exception of the 700 have the same width dropouts, so that is our goal. The main provisions will be to accommodate the different track widths of the 20-inch models. We also want a 26-inch wheel version for the Expedition. With this I also want the Quad conversion to be a bolt-on setup that does not require any modification of the Catrike frame. 9. Powered options. In addition to the Bionx middrive option I would also like to have provisions for a gas engine or electric motor that functions independently of the middrive choice. 10. Cargo options. The main loads should be carried on the Quad's rear axle assembly. Options such as racks, basket, platform, trunk should be easy to mount.
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One of the things that I wanted to make sure we incorporated from the beginning is the stock rear-wheel mounting position for the middrive and the derailleur hanger to allow for adjustment of the boom. This will also allow us to use a standard derailleur-based middrive for the best performance.
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The Quad axle is mounted to the Catrike frame using 4 elastomers. The elastomers act as a suspension and isolate the wheelstays from the frame twisting affect during cornering on the road.
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On the Catrike Quad we are using the Samagaga differential and splined axle system. The axle is held inside of the axle cage with the use of high-strength circlips. We have spaced the axles and splines so that there is 3mm float of the differential laterally to allow for minor chain movements.
