My Sun Trip Bike, Back to Back Tandem Trike with Rowing Generator, Pedals, +Solar

[justin_le]

As many of you know from our blog I'm not only sponsoring part of the 2018 Sun Trip solar ebike race this year (by creating data logging box for each vehicle shown here), I'm also participating in it with my fiance Anne-Sophie . What the people organizing the Sun Trip don't know, or would be very concerned to know, is that I haven't even started building my bike yet Oops. For whatever reason I seem to be a sucker for setting myself up for last minute engineering heroics, delaying the start of a project until there is physically just barely time to pull it off.

My plan for this is a little crazy, and with only 60 days to have it fully built and tested before we ship it to France, this is going to be tight. What I want to make is a back to back recumbent trike, very much in the spirit of this one-of-a-kind device pictured here:
http://hollerit.blogspot.ca/2010/06/hottest-trike-in-existence-is-also.html



The back to back tandem in this case provides an awesome stowage cavity for gear in between the backs of the two seats. It also allows both riders to have their heads closer together to facilitate conversation, and it gives us 360 degree visibility should something untoward be coming from behind.

But rather than having the rear rider pedaling a crank like the trike above, I want the backseat of this trike to be a rowing machine instead. This way, we can get a chance to mix things up and between pedaling and rowing during the long days of solar assisted travel and get a much more varied workout instead of sitting in the same saddle for 8-10hrs straight. It also serves as training for some long distance ocean rowing trips that we have in mind later in the summer.

Rowing bicycles have long fascinated me and I recently had the fortune to get some riding experience on the exquisitely made THYS 209 machine
https://endless-sphere.com/forums/viewtopic.php?p=1362573#p1362573

There is apparently even a back to back tandem one of these made too,
https://rowingbike.com/en/posts/model/thys-carbon-tandem/




Initially I was hoping to add another twist to this whole build, and that was to have both the pedaling and rowing stations be spinning generators so that there was no mechanical drivetrain to the wheels. That opens up mechanical versatility to the project with some obvious penalty in efficiency. Unfortunately the rules for the SunTrip race require that there is a direct mechanical link to the wheels. But they don't specify on a tandem vehicle if both riders need this link. So the plan is to make just the rear facing row station run a generator, which should be easier mechanically than coupling it to the pedal drivetrain.

And of course being the sun trip we need a serious amount of solar coverage. The plan for that will be a roof structure covering the entire length of the trike, giving us welcome shade while generating our daily power quota.

 

[amberwolf]

For whatever reason I seem to be a sucker for setting myself up for last minute engineering heroics, delaying the start of a project until there is physically just barely time to pull it off.
You're not the only one with this problem.

So the plan is to make just the rear facing row station run a generator, which should be easier mechanically than coupling it to the pedal drivetrain.

That depends...if you are making it a tadpole like the Trice, couplling pedals/"oars"/etc to the rear drivetrain would be easy, compared to doing it for teh front rider (which will either have a very long chainline, or need something like a U-joint axle to couple to one of the steerable front wheels (or both of them).

Since you'll be using a rear rowing setup, you should be able to pretty easily have the "cord reel" setup to get the power into the drivetrain in the correct rotary direction, compared to having to "flip" a pedal chain drive direction around (or to learn to pedal backwards).

 

[quantumcloud509]

wow cool

 

[GUI13]

hello justin, very happy to see that your bike "is on the way "
concerning the regulation (which I co-authored) and the obligation of a mechanical link beetween pedal and wheel, this rule applies for the driver of the tandem so no worries for AnSo to have a crank generator .
This rule has been put in place that we wish to have real bike (not some kind of Twike) but also for security reasons (to advance the bike if technical problem with the engine)

Good luck for the future !

 

[e-beach]

... I'm also participating in it with my fiance Anne-Sophie....

Congrads on your upcoming nuptials. May it last for over 100,000 years.

Oops. For whatever reason I seem to be a sucker for setting myself up for last minute engineering heroics, delaying the start of a project until there is physically just barely time to pull it off.

Well, since you put it out there, that is typical of a "last minute boss". You probably feel that you have other things that need attention before the project at hand and when you get it done in the last minute you feel a gratification by "pulling it off".

If it only affects you, then it is not a problem, but if it affects your employee's or other people in a negative manner, then you are just being selfish and disorganized in their eyes. Over the long run you might loose good people that way. Pick and choose your last minute project victory's. It will be easier on those around you. :wink:

My plan for this is a little crazy, ....... I want the backseat of this trike to be a rowing machine instead.

It will get you in great shape for your wedding, however, women (generally) have weaker upper bodies then men. You might end up with more time in the back seat then the front.

Anyway best of luck with it!

 

[justin_le]

hello justin, very happy to see that your bike "is on the way "

Well, as of today it is "on the way" for REAL. The last 2 weeks I've been pouring over various trike design and trike builds and looking for used trikes for sale that would be suitable for hacking up and converting into this solar tandem. My original original plan was to build the frame from scratch over winter by doing another of the Paul Brodie frame building workshops. We were going to host a special 3 week course for custom ebike frame building, and then make the chassis during this workshop. The time window for that option has sadly slipped.

Anyways quite out of the blue in the hunt for hackable trikes we came across this on Craigslist:





A Tandem Terra Trike ready to go! And my partner was already driving up through Seattle on an unrelated Easter weekend trip, so Whidbey Island was just a ferry hop detour on the way back to Vancouver and last night this rolled into our door.

It wasn't so clear from the photos, but this looks to be just the perfect platform for our project. The simple square tubing makes it easy to hack and weld/clamp on attachments for the rowing rig and solar canopy. And the seat supports are just clamped to the square tube too so it'll be no problem to flip one 180 degrees for the back to back configuration. And the two front wheels are both 20mm thru axles with hollow spindles so it should be no issue to fit the All Axle hub motors on those and have the cable loop through to the inside of the frame. I'm pretty pumped!

One thing crazy about this bike is the gearing. It has a double chainring on the front, a double chainring on the jackshaft, a 3 speed SRAM dual drive IGH in the rear, paired with a 10 speed cassette. That's 120 total gear ratios available to the riders. I can't get my head around how you'd navigate through that in a systematic way.

This rule has been put in place that we wish to have real bike (not some kind of Twike) but also for security reasons (to advance the bike if technical problem with the engine)

Interesting, so in principle this would allow for the kind of electric drive that Tig implemented in his Electrom vehicle?
https://endless-sphere.com/forums/viewtopic.php?p=1363944#p1363944

He's got the pedals linked in parallel both to a generator and the rear wheel. When the vehicle is above a certain speed then the pedals are simply running a generator as there is a freewheel in the mechanical linkage to the wheel. But as the vehicle slows down, at some point (~10kph in his case) then the mechanical drive becomes engaged.

That does negate some of the benefit of the electric drive (no mechanical transmission to worry about) but it would still allow a team to explore this solution while meeting the rules with a mechanical backup.

 

[Cowardlyduck]

Love this project Justin!
As one who has done some experimentation with solar on my recumbent, I would suggest putting at least one of the panels in front to break the wind. I found doing this on my BikeE reduced the cruising (~40-50kph) power consumption by about 100W average. I believe it's because it creates a nice laminar air flow around my body.

I recently went from a 15W panel to a larger 30W panel up front and have been finding the aerodynamics are now even better. If it didn't start to obstruct my vision or pedalling I would go even bigger.

https://endless-sphere.com/forums/viewtopic.php?f=6&t=57751&start=275

Also be aware that the 'flexible' panels don't like being bent too much as the silicone wafers can start to crack. I've had this happen twice to me now, once resulting in reduced output of the panel, and the most recent time I've had to completely replace the panel as it stopped putting out power all together. I would still advise using flexible panels as they are far lighter and easier to work with than rigid, however just be careful when mounting and forming them to shape.

Keen to see how this turns out!

Do you already have panels and a power unit in mind? I will be interested to see how you plan to send the solar energy to the wheels in an efficient manner. I my case I just used a cheap DC-DC converter and accepted the losses, but a voltage boosting MPPT, or a low voltage controller/motor would be ideal.

Cheers

 

[justin_le]

Well this weekend is when I officially start the build transformation and generally try to extract myself from so much day to day operational grind at Grin! Let's see how succesful I am at that We're also going to try and make something of a weekly video blog about the build project, milestones, decisions etc. and the first post for that from last weekend is Live

[youtube]WWE4XqAO0BM[/youtube]

Do you already have panels and a power unit in mind? I will be interested to see how you plan to send the solar energy to the wheels in an efficient manner.

The Panels themselves I don't have yet and will need to get a line on soon since that will affect the dimensions and construction details of the solar rooftop. We'll be looking to fit on the full 3 square meters worth of paneling allowed by tandem bikes in the race, in roughly a 90cm x 350cm rooftop that has some degree of adjustable sideways tilt so that we have the option to angle it more optimally towards the sun.

But the main next priority for the build is going to be sorting out the rear facing rowing station, since that has the highest degree of uncertainty and will require the most field testing to prove out.

 

[liveforphysics]

Sounds like such an amazing trip to ride from France to China!!! Wow!!!!

Congratulations on diving into the project and I wish you the best of luck in what will no doubt be an incredible enriching life experience no matter the outcome!

 

[PaulD]

Sounds like an amazing adventure, Justin! Much respect for taking this on.
For solar panels, I noticed sunpower sells their cells for individual projects which are pretty efficient. I've always wanted to do a project with them, but never had a chance. https://us.sunpower.com/buy-solar-cells/
Best of luck!

 

[liveforphysics]

Sounds like an amazing adventure, Justin! Much respect for taking this on.
For solar panels, I noticed sunpower sells their cells for individual projects which are pretty efficient. I've always wanted to do a project with them, but never had a chance. https://us.sunpower.com/buy-solar-cells/
Best of luck!

Those gen3 top tier cell numbers are amazing, and for something with so little total cells needed the $/watt doesn't really matter.

If you have issues meeting minimum order qty of 1500 cells, I would be happy to take 250 of them myself for a solar aero battery trailer concept for an attempt at reaching the south pole by solar ebike. Excited to see your solutions and real-world discoveries on the trip. You may want to train to build calluses and experiment with finding the best glove for reducing hand abrasion. I'm not an expert in rowing, but I've heard epic distance endurance rowing event pros end up with chowdered hands afterwards even using the best gear they have. This motion might not have the same angular shifting that might induce the skin abrasion effects though, I would love to try riding one.

 

[Warren]

Or you could just buy a panel from the notorious JR.

http://store.evtv.me/proddetail.php?prod=200wsolarpanel

http://store.evtv.me/proddetail.php?prod=120wsolarpanel

 

[justin_le]

Congratulations on diving into the project and I wish you the best of luck in what will no doubt be an incredible enriching life experience no matter the outcome!

Thanks Luke! I just this weekend got word that my business visa application for Iran has been approved, that was the one main uncertainties in our planned route since Canada/Iran diplomatic relations aren't so hot right now. We're probably not going to make it all the way to China in this run since me and AnSo have plans to get married in August (I think that's an OK excuse not to finish ), but we'll get as far as we can, and either pick it up later or find some other pair of people to take over the vehicle.

Having the trike make it all the way to China coast would be ideal, because then we could in theory ride with it as a paying passenger on a container ship back to Vancouver. Another little travel dream.

For solar panels, I noticed sunpower sells their cells for individual projects which are pretty efficient. I've always wanted to do a project with them, but never had a chance. https://us.sunpower.com/buy-solar-cells/

Oh awesome. Those cells are less expensive than I was expecting. It wasn't quite on the radar to build up a panel from scratch cells but you've got me is tempted by this for both a) the DIY aspect, and b) the possibility to configuring them in a series string that is effectively optimized for max power into our Lithium pack without a MPPT charge controller. I haven't quantified from the V-I graphs but it seems you could set it up so that on average your losses from not always loading the the cells to the exact max power voltage (over varying temps, sunnlight, and battery SOC), aren't far off from DC-DC converter losses.

I'm not an expert in rowing, but I've heard epic distance endurance rowing event pros end up with chowdered hands afterwards even using the best gear they have.

Oh yeah, I've had my share of that even on not-so epic rowing events! Part of is you said is that on a boat you are using your hands to manipulate and feather the oars, and there is a lot of relative motion as you grip and twist that causes calluses and blisters. I'm hopeful that on the rowing bike it will be possible to have a grip and hand position that is easier on the skin since it's just a straight pulling motion all the time. I'm sure some of the regular rowbike rowers/riders can chime in? I know there is at least 2 or 3 on this message board!

 

[Warren]

I definitely had calluses on my hands when I was riding my rowbikes. I also wore bike gloves.

Most regular folks can produce about as much effort through their arms, as they can through one of their legs. On my setup, I could adjust the kevlar cable attachment point, on the steering riser, so that the arm effort was more realistic for non-gorillas. This obviously also put less pressure on the hands.

 

[ScooterMan101]

Justin and Luke

Now that you know that individual solar cells are available to buy,
Keep in mind that you must lay them onto a surface that will ... Not , contract with the different temperatures in a 24 hour period.
Too much contracting and expanding of the sub surface will crack the cells.

I think a thin film of epoxy on top will help protect the cells from any rain/moisture. Look into what the people that have boats do when they put a cell/panel on the deck and want to walk on the panel and protect it from the elements. If you don't want to or do not have the time to epoxy the entire upper surface you can get thin lexan/plexiglass to put on top then epoxy/silicone around the sides.

I am going back several years in memory, back then thin stainless steel sheets are/were best for the under surface , with epoxy or plexiglass on top.
Years ago I also looked into " Orange Board "
Orange Board is the honeycomb composite floor boards that are/were used in Boeing Aircraft.
Back years ago it was available on at low prices , but then someone got an exclusive buy on the surplus stock and raised the prices too high to consider it.
Perhaps that has changed by now. or someone else is making the same / nearly same thing.
It could make a good base for a solar array trailer that Luke , ( and I have been wanting to make for several years now ) and the roof for your trike as well, Justin.

When making a tilting frame for the solar panel, if you plan on tilting it while riding look into aero shaped tubes for the vertical tilting bars. You can see examples of these by looking at what hang gliders use on their down tubes.
You should be able to find smaller versions that will be better on the trike.

The Panels themselves I don't have yet and will need to get a line on soon since that will affect the dimensions and construction details of the solar rooftop. We'll be looking to fit on the full 3 square meters worth of paneling allowed by tandem bikes in the race, in roughly a 90cm x 350cm rooftop that has some degree of adjustable sideways tilt so that we have the option to angle it more optimally towards the sun.

 

[ScooterMan101]

C D , looking at the picture of your bike-E it looks like you can use a bigger panel on the front , by making a bracket that extends the lower part of the panel out further and at more of an angle .
Also to be able to see above the panel just buy a wind deflector that some motorcycles use on their windscreens .

https://www.ebay.com/p/Universal-Clear-Wind-Deflector-Windshield-Windscreen-High-Spoiler-for-Motorcycle/602181059?iid=192364036766&chn=ps

Love this project Justin!

I recently went from a 15W panel to a larger 30W panel up front and have been finding the aerodynamics are now even better. If it didn't start to obstruct my vision or pedalling I would go even bigger.


Cheers

 

[fechter]

That's quite a long ride. And through some pretty dangerous territory. And HOT. Using the solar panels for shade will be a really good idea. Getting lost along the way could be bad.

Congratulations on getting married. Just make sure you both come back in one piece.


Here's a link to the technical rules:
https://www.thesuntrip.com/sun-trip-2018/technical-informations/

I didn't see anything about weapons...

 

[billvon]

Oh awesome. Those cells are less expensive than I was expecting. It wasn't quite on the radar to build up a panel from scratch cells but you've got me is tempted by this for both a) the DIY aspect, and b) the possibility to configuring them in a series string that is effectively optimized for max power into our Lithium pack without a MPPT charge controller. I haven't quantified from the V-I graphs but it seems you could set it up so that on average your losses from not always loading the the cells to the exact max power voltage (over varying temps, sunnlight, and battery SOC), aren't far off from DC-DC converter losses.

You might want to consider doing series strings only on cells that are oriented in approximately the same direction. MPPT controllers will "hunt" for the right operating point, and if two cells in the string are oriented different directions (i.e. one is generating 2 amps at .6 volts, the other generating 1 amp at .6 volts) it will not be able to find a single operating point that works well. At best it will 'settle' on a 1 amp string operating point (which all cells would then support) but you'd waste power.

If you decide to go without an MPPT controller you'll have to worry about temperatures as well as string lengths and orientations, since Si PV cells have a pretty strong negative temperature coefficient with respect to voltage. You can choose worst-case temperatures and design for that of course but you then leave a lot "on the table" in colder temps.

If you can organize strings that all face roughly the same direction, the Genasun series of boost MPPT controllers might work out very well. They're relatively cheap/light and can boost from fairly low voltages (i.e. a short string) to ~60 volts for charging 48 volt li-ion packs. They are spec'd to operate down to 5V input, which means a string of 12 cells would be sufficient to drive them.

 

[Cowardlyduck]

C D , looking at the picture of your bike-E it looks like you can use a bigger panel on the front , by making a bracket that extends the lower part of the panel out further and at more of an angle .
Also to be able to see above the panel just buy a wind deflector that some motorcycles use on their windscreens .

https://www.ebay.com/p/Universal-Clear-Wind-Deflector-Windshield-Windscreen-High-Spoiler-for-Motorcycle/602181059?iid=192364036766&chn=ps

Thanks for the suggestion...maybe jump over to my thread for further discussion, but I have considered these exact mods as well. Good suggestion. For now I'm sticking with 30W size as it makes it more practicable and manoeuvrable. I need to get a 3D printer first before I can play around with brackets etc to be able to go to the larger 50W panels. I'm also thinking of putting a couple of panels on the back in a 'tadpole' shape as this will also improve the aero significantly.

Cheers

 

[parabellum]

If you decide to go without an MPPT controller you'll have to worry about temperatures as well as string lengths and orientations, since Si PV cells have a pretty strong negative temperature coefficient with respect to voltage. You can choose worst-case temperatures and design for that of course but you then leave a lot "on the table" in colder temps.

MPPT controller is like 10x in complexity (part count) and 1/10x in reliability of PWM and like infinitely unreliable compared to direct system ex. diode. It will also weight much more and many parts must be protected against vibration on a bike application. And I would take 2 spares for trip that long.
On other hand, if array is not pointed to sun in uniform angle MPPT could add on efficiency. Temperature factor is only valid in extreme fluctuation.
I would use right series array to go direct charging and only consider charge controller as exotic toy to play with, until it fails.

 

[GUI13]

good idea justin than Vlog series ! like this we can control your work

for degree panel adjustment we work on automatic tracking ( gps control+ solar current )

first test on "www.lasuntravel.com" :

[youtube]jqowchDKIK8[/youtube]

 

[billvon]

MPPT controller is like 10x in complexity (part count) and 1/10x in reliability of PWM and like infinitely unreliable compared to direct system ex. diode.

Well, no. A direct system also requires a switch (or linear regulator) to prevent overvoltage. And linear regulators add the complication of thermal management.

It's like comparing brushed motors to brushless motors. Sure, brushless motor controllers are 10x the complexity of brushed motor controllers. But they work really well, and so have taken over. Likewise, MPPT controllers have taken over from PWM controllers for all but the simplest applications (solar yard lights, remote sensors etc)

It will also weight much more and many parts must be protected against vibration on a bike application. And I would take 2 spares for trip that long.

If you like. Homemade panels are far less reliable overall than an integrated charge controller. And they weigh about 180 grams - so you can bring a spare if you like without much penalty.

On other hand, if array is not pointed to sun in uniform angle MPPT could add on efficiency. Temperature factor is only valid in extreme fluctuation.

No, it's not. Let's take a typical example.

A 48V system (58.8V charge voltage) is used for a sunraycer type vehicle. You design for 5C (cold morning at altitude) to 50C (2pm in a low altitude valley in the sun) with cells that have a Voc tempco of -.38%/degree C That means that if you design your array for 58.8 volts at 50C (i.e. you get full charge at high temps) you will see 67 volts in that cold morning (i.e. 4.8 volts per cell.) That will rapidly destroy the pack.

Let's say you play it safe and instead design for 58.8 volts for the cold morning case. Now you are seeing 51.7 volts in the afternoon; 3.7 volts per cell. That won't give you much of a charge if you are already at 50%. All that solar will be useless.

"I can disconnect the cells if the voltage gets too high!" you might say. Yes, that's what a PWM controller will give you. An MPPT controller gives you the same results, but with 15% more power available.

 

[amberwolf]

I'm hopeful that on the rowing bike it will be possible to have a grip and hand position that is easier on the skin since it's just a straight pulling motion all the time.

What about using a (silicone?) grip formed to the hand that flexes along its length and is mounted to the bars by two (or more) roller bearings, at least at the ends (perhaps also the middle)?

Then each grip can roll freely (kind of like a grip throttle) to allow the rotation of hands vs bars, and also flex from each end of hte hand to the other so the hand can do its thing without rubbing against the grip itself.

 

[justin_le]

good idea justin than Vlog series ! like this we can control your work
for degree panel adjustment we work on automatic tracking ( gps control+ solar current )
first test on "www.lasuntravel.com" :

Oh sweet work! We were going to have a manual adjustment for the tilt of our roof canopy with telescoping support tubes and just tweak it now and then, when the sun is obviously more to one side of the other. But watching that automatically tilt back and forth as you corner around is pretty magical. Time to replace the telescoping support tubes with linear actuators now

Seriously Guillaume, that's nice work. I presume by you saying this is GPS control that you are using open loop angle computations based on your heading direction and position + time of day? Or is there a closed loop control based on optical sensors to sense the direction of shading and or the solar power levels?

You might want to consider doing series strings only on cells that are oriented in approximately the same direction

Yeah, since it's a rooftop canopy I can't see any advantage to doing anything other than a perfectly flat panel with all the cells on exactly the same plane and getting the same incident light. Curved panels arguably look better, but in this case make little sense.

If you decide to go without an MPPT controller you'll have to worry about temperatures as well as string lengths and orientations, since Si PV cells have a pretty strong negative temperature coefficient with respect to voltage. You can choose worst-case temperatures and design for that of course but you then leave a lot "on the table" in colder temps.

Yeah hopefully not too many colder temps on this particular trip. That's an interesting point about the MPPT tracking getting thrown off by local maxima from having differently oriented cells. If I do run with a solar charge controller I'll hook things up in a way to ensure that the panel strings can be easily re-configured for adequate voltage into the pack without a controller if need be. I have full confidence in the BMS board to do overcharge protection with this particular pack setup.

Congratulations on getting married. Just make sure you both come back in one piece.

And hopefully still as one couple too

 

[justin_le]

I definitely had calluses on my hands when I was riding my rowbikes. I also wore bike gloves.

OK, interesting to hear that firsthand. And I presume that's even without rowing it for 8-10 hours a day, day after day? I found on our rowboat that if I used normal gloves that cover my hands, the extra sweat/humidity could soften the skin and make it almost more callus prone than no gloves. But when we used weight lifting gloves that only covered the palms and were held in place with a thin strap, it made a huge difference.

Most regular folks can produce about as much effort through their arms, as they can through one of their legs.

I'm going to start posting sketches of the rowing mechanism I have in mind next. But basically, the idea is that the legs will be pushing on the pulley portion of a pulley system, while the arms will have the end of the rope, and that means that the leg force will be 2x the arm force while rowing, like they each have their own gear ratio. And I'm hoping that this leads to a better overall balance in the leg vs arm load distribution during the stroke.

The first stage of the trike conversion turned out to be way too easy. It was possible to flip the rear seat around 180 degrees into a back to back arrangement just by rearranging the original hardware with no custom parts or mods required at all.




That means in a pinch so long as I keep the original tandem cranks handy, it should be possible to do this rowing retrofit in such a way that it remains fully convertible. If it does crap out or prove unworkable in the really long haul somewhere in the middle of nowhere, we'd be able to flip the seat back to face forwards and revert the trike back into a pedal tandem if need be.

This Terratrike is really looking to be such an ideal platform, I still can't believe the luck in finding it on craigslist!