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Stella: hj StreetMachine

This bike will be the host machine for the e-components originally tested on the eG20 bike The main difference between the Bacchetta G20 and the HP Velotechnik StreetMachine is that the latter has a full suspension, which will make it substantially safer at speeds over 15MPH on poorer quality surfaces. It will also be more comfortable. The under-seat-steering (USS) also provides a better view of the road ahead. This bike is really the culmination of my estimated 60,000 miles on various human-powered land-based vehicles. Our shared german heritage is coincidental.

HP Velotechnik StreetMachine GTe 2019 model
Battery Rack Notes and photos about the custom battery rack made for Stella.
Headrest Notes and photos about the custom seat-mounted headreast made for Stella.
Photos Miscellaneous photos of Stella
Sample Trip Stats Data used to determine expected performance and battery range, etc.
Workstand (custom) Stella doesn't fit 'normal' bike work stands - nor the 'recumbent' work stand I made.






Craigslist photo taken by the bike's original owner, near Stillwater, MN. He bought the bike in 2019 from The Hostel Shoppe, a well-known recumbent dealer located in WI. The bike had about 20 miles 'on the clock' when my spouse got it for me as a birthday present. Thanks Debbie, IDYA!

HJ on "Stella" after bringing her home, May 2020.

First 'double-digit' ride. The view from Stella, pulled up at 38th and Chicago, Minneapolis. 1 June 2020. Notice the completely unobstructed forward view while reclining comfortably on the StreetMachine's seat.






Sample Trip Stats


Temp C
WattHrs Used
WattHrs In
Charge/Effic %
Notes &






Stella Workstand

Photo of Stella's front boom on mockup workstand. The boom inner tube (black part) has a diameter of 2.097", and will be used as the main support for the front of the bike. It's a perfect fit for the rubber mounts from the old Seph/Les bike rack permanently seized onto their VW. These rubber mounts are designed to fit onto stock 1" (OD) pipe.

The rear part of Stella will be supported by a rear rack cobbled together from parts I've scavenged previously from other bikes or Erik's dumpster. This photo shows the back end of the bike with no rack installed yet, supported by a rubber bumper holding the rear rim.

The rear components which equate to an upright bike's chainstays are aluminum tubes with a very slight taper, becoming smaller towards the rear axle. The top tubes vary from slightly more than 7/8" diameter to slightly less. If we were to use Jubilee clips as attachment points for the rear rack, the 7/8" spec would probably be about right. Remember that the chainstay assembly moves independently of the seat assembly (due to the rear suspension), so do not use fixed supports that tie the two together, as many traditional rear racks do.

The first thing to do when working on the underside of the bike is to make sure your bike workstand will hold the bike upsdide down.

Yup, it does.

The following photo ...











There are two threaded inserts for M? screws in the top center of the seatback. The inserts are located in a recessed channel, so any bolt heads or other parts used to fasten a headrest here would be hidden (and leveled) by the seat's foam cushion. The velcro holds the seat cusion to the seat itself. I'll use a sharp knife to remove the velcro in the actual channel, leaving two tabs, which will be adequate to keep the top of the foam cushion from flopping around.

I plan to modify the carbon fiber headreast I made for the G26 to fit in this channel and be adjustable with a limited amount of vertical movement. The idea is to have the headrest pad fit below the helmet, so it's actually a 'neckrest' instead. This has worked very well on the G26 with the laid-back seat, where it came in handy for the occasional need to rest on long trips.









Battery Rack

Photo of eStreetMachine_stella_battery_rail -- coming (hopefully) soon (when it's actually made)


Battery Rack - front mount

Looking at the right side of the main tube just behind the under-seat steering (USS) tube. The white plastic is a template model of the battery support clamp being made for this location. The top of the mounting bracket just clears the swinging steering 'handlebars'. I'll add a small rectangular notch to allow some clearance for the chain return tube, which shows just slight interference here. I designed the bracket with four symmetrically placed cable pass-throughs, only one of which may be needed, as seen here.




Battery Rack - rear mount

Underside of main tube near the middle, showing the black plastic bracket that holds several control cables going to the back of the bike. It is held to the tube with a single M5 bolt. The battery rail will have to work around these cables. It might make sense to divide them and re-attach them on the sides of the main tube.

Going further on the bottom of the tube towards the rear of the bike. Note the two small black plugs which are protective covers for additional threaded mounts in the tube. Their spacing suggests they might be designed to hold a water bottle cage. Also note an unplugged holes in the main tube further back for drainage of any moisture that might accumulate in the tube.

We're now looking at the very end of the main tube, bottom view, where it becomes the rear suspension joint. The drainage holes are now easier to see. I've loosened and removed the M5 screws used to hold the plastic cable bosses/mounts, which are on approximate 3"/75mm centers. These tube mounting points will be repurposed for supporting the rear of the battery rack.

To make it easier to get the right measurements and test the fit of new parts, it's best to mount the bike upside-down in the workstand. The following shows the spacing between the M5 screw mounting holes on the bikes bottom tube, with the rear of bike towards the right.

Here we're seeing if a scrap piece of 4" wide aluminum "U" bar stock can be turned into a rear support for the battery rack. There is an approximate 20" (max) of space available under the main tube, between the front and rear wheels. Towards the front, the need to maintain clearance between the rack and the front wheel's fender will be a major issue. Maintaining a smooth chainline is also a major consideration.

Here we see that the main tube starts curving slightly upward starting about 6 inches forward of the rear main suspension hinge. Since the rear mounting plate will be absolutely flat, we'll need to make a shim to go between the plate and the tube at the very forward bolt. The gap is approximately 4-5mm, including the height of the threaded boss.

Let's use Delrin, one of our favorite plastics. Made the curved part on the drivewheel of a belt sander, drilled center hole to 0.41" and cut to length on the lathe with a cutoff tool. Machined Delrin smells horrible, but the swarf is magnificent.

This cheap and easy method for transferring the four screw boss locations to a piece of paper requires several old aluminum tent pegs with 'sharpened' points. This coupled with a digital 6" caliper allows sitting comfortably at a computer when designing the CNC toolpaths to machine the holes. The holes themselves are threaded for M5 screws, but the welded on bosses stick out from the tube. The drainage holes need to be kept clear. Rather than having the rear mounting plate 'float' on top of the bosses, I decided to machine 0.41" clearance holes for these bosses and have the plate fit against the tube itself.

After the laying out the basic design for the rear mounting plate, it's time to begin producing aluminum swarf. Here the five holes (4 mounting, one drainage) have been machined, plus the beginning of the side cutouts of the "U" bar that won't be needed for support. This extra aluminum wouldn't be in the way, but its unecessary weight. The CNC machine is a ShopBot "HandiBot" model, being used by courtesy of JPods, Inc. Cuts are being made by a two flute, upcut 0.25" solid carbide endmill, using light passes. The bit's cutting edge has to move fast enough through the material to prevent friction welding, but not bog down the lightweight router motor. I've had the most success with light passes and slow plunge rates coupled with normal-to-high travel speeds.

Checking the fit of the freshly machined plate on the bottom of the bike. As Gino says, "Good enough for the government." Some additional machining will be required to provide clearance for the M5 hex head SS screws for the rear two holes, which are by necessity too close to the contoured insides of the U bar. The started side cuts will be finished on the bandsaw.

A poor man's milling machine. Not ideal, but slow hand work with the crossfeed slide on the lathe lets the 3/4" carbide straight bit remove enough metal. Any chatter and the wrong approach will break off a corner of the carbide cutting edge -- don't ask me how I know this. It is, after all, mis-use of a bit made for woodworking. I would have used the CNC but it was quite a reach for the endmills I had on hand.






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