Carl Chatfield home page | Getting from A to B | Electric Bicycles | 2-Stage Rocket
| Update: After riding this E-recumbent for many miles, I decided to try something different. I moved the power-assist system from this bike to an Electra Townie upright bike (aka The Shocker), and restored the Giro to its original unassisted form. As such the Giro is a very fine short-wheelbase recumbent, and I still enjoy riding it. One unique feature I discovered is that I can fit this bike onto the standard bike racks on our local transit busses by simply turning the front wheel around 180 degrees. It then fits in the rack perfectly. --Carl, December 2004. |
(Click on thumbnail images to see enlarged (640-480 pixel) images)
I also call this bike "The Scorcher." The first bikes seen in cities prior to and at the start of the 20th century were called scorchers because of their (relative) high speed in dense urban settings. Nickname I vetoed: "The ElectiCute."
But "2-Stage Rocket" is also apt for this very fast, very fun bike. Here are the basics:
The bike itself is a Bacchetta Giro short wheelbase recumbent bike. This is a fantastic bike. The obvious modifications and additions I've made include the following.
This is provided via two Heinzmann hub motors. In the front 20-inch wheel is a Heinzmann "City" 36-volt, 500-watt motor. In the rear 26-inch wheel is a Heinzmann "Solar" 36-volt, 830-watt motor.
Tying it all together is a single rack-mounted NiCad battery, controller and throttle, and a very clever toggle switch mechanism (throttle and switch shown in left image above) to switch power between the front or rear hub motor (switch box shown in right image above). This design uses the motors in series, not in parallel. The performance of the two motors, in conjunction with the two wheel sizes, gives me an excellent combination of power-assist.
Stage 1 is the City motor in the 20-inch front wheel (shown above). This is a low-speed, high-torque motor and will accelerate me from zero to around 14 MPH, and (in conjunction with the excellent gearing of the Giro) get up any grade of hill I'm likely to encounter. This motor is somewhat louder than the Solar, and amplified by the fairing, but certainly not unbearable.
Stage 2 is the Solar motor in the 26-inch rear wheel (shown above). This is a high-speed, low torque motor and picks up anywhere from around 12 MPH up to approximately 30 MPH on level ground, with active pedaling on my part. The Giro is well geared, so with some enthusiastic pedaling I typically maintain a 20-28 MPH average on level ground, engaging the Solar motor as needed. I can burst up to around 34 MPH for short sprints. The Solar also performs well on moderate uphill grades when I can maintain at least 15 MPH with enthusiastic pedaling. Below that I switch over to the City motor and keep keep spinning around 12 MPH up moderate grades. The Solar motor is amazingly quiet when engaged.
The stock Giro weighs 30 lbs. My modified 2-Stage Rocket tips the scales at a hefty 70 lbs (that's with the battery onboard, but without fairing or tailbag).
The front fairing is a clear lexan Mueller Windwrap RS with One-point mount. Installation was fairly easy, and the mounting brackets offer plenty of adjustment range. I had some experience with a fairing on my BikeE recumbent, so I expected the weather protection a fairing affords and on the Giro I actually achieve speeds where the aerodynamic benefits of the fairing exceed its weight penalty. My guestimate is that the fairing adds 2-4 MPH to my speed, more as I go faster. Like any front fairing, the RS tends to amplify road (and in my case, motor) noise kicked up by the bike, and funnels it back at me. It's not that loud, however. The fairing can also react to sidewinds, and I've had it out in some fairly strong winds. This fairing mounts to the main body tube (or boom) of the bike and not to the front fork or steering wheel, so wind pressure does not affect steering as much as it did on my BikeE. On the BikeE the fairing was attached to the front fork and handlebar.
The tailbag is made by Angletech, and is called the Aerotrunk. It's large enough (2,850 cubic inches) for everything I otherwise would transport in two mid-sized panniers. It's big but light, highly visible, and sleek. I thought it might bob from side to side or otherwise introduce some strange vibrations to the bike, but it's been very stable. Given the battery weight I'm putting on the rear rack, I'd rather not overload it with my gear so the tailbag, which mounts to the seat back, is a good option.
I'm now commuting on the 2-Stage Rocket year-round. The bottom bracket on the Giro is fairly high--much higher than on my BikeE or, of course, on an upright bike. Initially I found that after a few miles of riding I'd develop some numbness in my feet and toes, which I understand is not uncommon with high bottom-bracketed recumbents. I've gotten into the habit of using clipless pedals and shoes, and that seems to have fixed the numb feet problem (and improved my cycling efficiency).
This bike allows me to travel at just about the maximum speed I should travel on a two-wheeled vehicle in traffic, and maybe a bit faster. On my regular route to work I often can maintain the posted speed limit for vehicle traffic. Like most recumbent riders, I find that my visibility is very good in traffic. The Giro is a short-wheelbase recumbent, but at 47.5-inches, it's on the long side of short wheelbases. At low speed turns I occasionally will bump my heel on the front wheel, but never hard enough to cause a spill.
In short, this is a great power-assist bike. I went through three other e-bikes of various designs and quality and a lot of research to figure out what I liked and didn't, and I'm looking forward to putting thousands and thousands of miles on this 2-Stage Rocket.
Updated
12/23/04