A couple of commuters for ya.
It’s taken me a couple attempts to figure out how to make my commute in a sustainable manner. My commute is 30miles each way, 20miles of that being gravel with a river valley and a couple of creeks to cross on either end. I work 7:00 to 3:30 or 6:00 to 4:30 five days a week as a machinist. The rest of the time I’m just a bike nerd.
My first attempt was on my custom Badger CX bike setup for commuter duty. This bike was built to accomadate 29×2.0 tires with fenders and has Surly horizontal dropouts with a der tab for use with gearhubs/singlespeed use. Odd mix of rock solid components including a White Industry cassette hub, Schmitt Dynohub, Paul brakes, Square taper FSA crank, XT Shadow rear der, Shimano600 8sp brake shift levers, Thomson stem, Ritchey Biomax bars, Planet Bike Cascadia fenders, and Brooks saddle.
I tried riding a mock bicycle commutes a few times on weekends, it was taking me 2-3 hours to ride in depending on the wind and gravel conditions, and that wasn’t going to be an acceptable or sustainable commute five days a week.
I thought about adding an electric assist, but considering the conditions I would be putting it through and what I wanted out of it, it just wasn’t penciling out. So started brewing up ideas with other projects I’ve been wanting to try out. I started with an old Schwinn Homegrown and an Xtracycle kit and here’s what I ended up with:
It’s still a work in progress, but it has made the difference between being able to bike commute and being stuck in the steel cage, err, car.
My assist is designed to run the constant on the way in, boosting my avgerage speed to 30mph, hence cutting my commute time down to an hour regardless of conditions. The motor is a 33cc 4cycle Suburu/Robins with a centrifugal clutch, this drives a Staton-inc 18.75 to 1 two stage gear to gear reduction. I have a freewheel on the gear reduction which then drives a cog on my central jackshaft which then drives the rear wheel. There is also a freewheel on the jackshaft for the pedal chain, so the pedals freewheel separate form the motor drive, and the motor freewheels separate from the pedals. The motor is rated for a peak of 1.76Nm of torque at 5000rpm and a peak of 1.18kW power at 7000rpm. I geared my 80rpm cadence(my peak torque) to match the motor’s peak torque at 5000rpm. This puts the motor’s peak power at 7000rpm to my 110rpm cadence which is pretty close to my peak power.
The final drive is through a Fallbrook Nuvinci continuously variable gear hub which allows a constant rpm input, helps maximize my fuel economy, and boosts my speeds. Geared the way it is now, running at full throttle unassisted, the motor is getting about 120mpg. More pedaling equals better fuel mileage and/or higher speeds.
I know my drivetrain is woefully inefficient, with the gear to gear reduction and all the chains open to the elements, but it was the somewhat readily available starting point and I was tired of waiting. The next version will be much improved with all the chains and gear to gear reduction replaced with a custom fully enclosed Gates cog belt drivetrain I’m working up to fit on a much stiffer Surly Big Dummy frame.
Fairing will make the next big difference. Originally my plan was to modify a moped as a recumbent frame and fair that, and I may still, but the Xtracycle sure opens the doors to carrying capacity. I’m not sure how the upright fairing will handle, I guess I’ll find out. I plan on keeping it low. I’ll tuck down to complete the shape for maximum efficiency, and sit up for stability on the sketchy sections of gravel and traffic, and retain the ability to stand and climb. I’m planning on using a combination of Zote, Coroplast, and Lycra or some other flexible material over a frame to keep my carrying capacity and maximize the usefulness of the bike. The lack of carrying capacity in velomobiles has been a pet peeve of mine for awhile. Fast is good, but what use is it if I can’t use it for anything?
Anyways, enough of my rambling. There’s a bit more info and insight on what I’ve been doing with this creature and what lead me to it on my blog here: www.nonconformcycling.blogspot.com —Dennis