Almost as soon as we made the official announcement of the Utah Trikes Quad, we got enquiries about power assist options. Well, the good news was that we had been working with some gas assist options already. We posted one of the early prototypes on our articles page a while back. Well, after much more testing and the help of several local Quad customers whoe were willing to do a lot of testing for us, we have finally acheived what we wanted. Sid's quad is one of the first of our "standardized" Gas Quads. It features a custom rear end with the Nuvinci transmission and motor tied to the rear axle assembly. It's fast and solid!
One of the first things that we learned in developing the Gas option for the Quad was that the Nuvinci and the motor needed to be joined together on the rear axle assembly. Here you can see the right side of the motor assembly and two of the three chains.
Here you can see the left side of the motor assembly and the primary drive change from the Nuvini mid-drive transmission. You can tell that the placement of the whole setup has to be very precise because of the clearance issues. You can also see that for our final version we have moved the seat stays to the motor mount, which shifts part of the rider's weight directly to the Quad rear end.
The motor slides forward on the axle mount and is secured via the sloted plates and a plate on the bottom of the motor mount. This adjusts the tension of the primary drive train going to the positraction axle.
The threaded shaft you see is used to adjust the tension of the motor drive chain going from the gear reduction box (motor) to the Nuvinci's input shaft.
To keep the pedal chain lined up on the Nuvinci's freewheel it is necessary to keep both sides of the chain lined up with a stacked idler arrangement. The chain tension is set by sliding the idlers towards the rear of the Quad as needed.
You can also see our aluminum brace that triangulates the motor mount between the Quad rear axle assembly and the frame. This piece runs nearly parallel to the drive change and completely eliminates any flexing at the rear end from pedaling or from the torque of the motor. This piece alone allowed us to get 5 MPH more out of the Gas Quad.
The quad has great ground clearance. With no derailleur hanging down and raising the idlers up there is a lot of room.
The Nuvinci CVT transmission is at the heart of our Gas Quad. With a dual freewheel setup you can pedal without the motor, or use the motor without pedaling. Best of all though, you can pedal and use the motor at the same time for max power, speed, and workout. The Nuvinci transmission has no gears and allows you to select the best ratio for power or speed.
The Nuvinci's shifter is a twist/grip shifter. There are no distinct gear positions, instead you twist it one way for a low ration and the other way for a high ratio.
Avid BB7 brakes
If you go with gas you need the larger brake pads of the BB7 or Juicy brakes. The BB7 is also easier to adjust than the lower brake options.
With the high speeds the Gas Quad is capable of we highly recommend the Marathon Plus tires. Believe me, you want more rubber.
Avid BB7 brakes
The BB7 brakes are adjustable from both sides of the caliper without tools.
The kill switch is mounted to the top of the handlebar mount for easy access.
The Nuvinci is setup with a double sprocket on the input shaft. The larger sprocket is lined up with the gear reduction box on the motor. The smaller freewheel is connected to the pedal chain.
Primary Drive Sprocket
The Primary drive sprocket is bolted directly to the Nuvinci transmission.