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Tandem eBike conversion - Lessons learned

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Tandem eBike conversion - Lessons learned

Old 07-03-22, 03:46 PM
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The motor is on the rear and the pedals are in sync
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Old 07-25-22, 06:52 AM
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I see that the sync chain is, well a chain, not a gates belt. Are belts not an option for the motor drive?
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Old 07-27-22, 08:41 AM
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We have the Gates belt on ours. It requires an extra long Phil Wood spindle and bottom bracket assembly.
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Old 07-30-22, 09:53 AM
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Why electrify a tandem

Originally Posted by merlinextraligh
At the risk of setting off a sh*t storm, why electrify a tandem. A major reason to ride a tandem is its ability to allow riders of unequal strength to ride together.

E bike singles accomplish the same purpose. While I’m beginning to see som place for Ebikes, not sure an Ebike tandem makes a lot of sense
My husband rides with our adult son with disabilities. My son loves to go fast so he “helps” push when they’re not going slow. This means he doesn’t help much on hills!

At age 69, my husbands knees hurt if we ride up too many hills. The electric motor would help his knees and allow us to ride together more often.
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Old 08-16-22, 09:52 PM
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Originally Posted by DubT
I installed a Bafang BBSHD mid drive kit on our Calfee tandem a little over 3 1/2 years ago. The tech at Calfee gave me technical support and told me exactly what to purchase in order to make the installation. We have over 20,000 miles on the kit and are extremely happy with the results.
[...]
We always ride with the PAS engaged, we have 9 levels of assist and I normally run in level 1 or 2. Mileage is dependent on the level of boost selected but we can easily ride 60 miles on level 2. Probably 100 miles on level 1.
I have a throttle which I use every time we start and if we need an additional boost on a hill etc. I also have a motor kill button that I use when I shift gears.
There is no way we would go back to non electric assist!
If I were to build another bike I would do it just like this one.
If you want additional details/pictures etc. send me a private message with your email address.

Wayne
Hi, Wayne,
I am rethinking my conversion of a Cannondale Los Dos tandem 2 years ago. I used a 500W Bafang rear-hub drive and it works fairly well - I'll post some pictures here.
However, I find the bike top-heavy, even without a battery. The hub did offset the rear cassette a bit and it has become a pain to adjust shifting.
More importantly, I am concerned about the difficulty of removing the rear wheel in case of a flat; also, I do worry about over-stressing the rear dropout by the torque arm.

I am thinking about mid-drive motor that would alleviate those concerns and also allow me to use a hub gearbox, like the Alfine, for further convenience.
Could you elaborate on your setup? Is your motor in captain's or stoker's position? Is the chain on the left? Before seeing your post, I have been thinking about using the Bafang BBSHD motor "upside down" in captain's position, to allow it to drive the timing chain. Is this what you did?
Unfortunately, I cannot PM you directly, as I do not have the requisite 10 posts yet.
Thanks, Robert.
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Old 08-16-22, 10:05 PM
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Originally Posted by merlinextraligh
At the risk of setting off a sh*t storm, why electrify a tandem. A major reason to ride a tandem is its ability to allow riders of unequal strength to ride together.

E bike singles accomplish the same purpose. While I’m beginning to see som place for Ebikes, not sure an Ebike tandem makes a lot of sense
Others replied already, it is an old (mature?) thread, but I'll add my vote.

I am still keeping my beloved Burley Softride road tandem. It is "pure", relatively fast and pleasantly weird looking - something to add to tandem mystique. We do like to show off...

However, we do not have as much energy as we did once. I electrified our gravel-trail tandem, the Cannondale Los Dos and it has been a great experience, both on rail-trails and on pavement. Yes, a tandem is an equalizer, but also it is a social experience and fun. It's much better to enjoy a long-ish ride on the e-bike, instead of longingly look at a "pure" machine hanging in the garage.

At this time, we use the standard and the e-bike about fifty-fifty.
Regards, Robert.
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Old 08-21-22, 09:25 AM
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Originally Posted by rdwalker
Originally Posted by DubT
I installed a Bafang BBSHD mid drive kit on our Calfee tandem a little over 3 1/2 years ago. [...]
Wayne
Hi, Wayne,
I am rethinking my conversion of a Cannondale Los Dos tandem 2 years ago. [...]
Thanks, Robert.
Wayne, thanks for reaching out to me. I tried replying, but am not sure if it went through on account of my "newbieness". Just in case, here is my address: ra at rdwalker dot com.
I will be taking some pictures today to post about my conversion for those who want to go the rear-hub route.
Robert.
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Old 08-23-22, 06:58 PM
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Never mind, I cannot post pix for the DIY thread until I have 10 posts under my belt. Working on that...
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Old 11-04-22, 03:57 PM
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Our recent conversion

My wife and I found ourselves not riding our tandem. She went eBike a few years back and following damaged lungs and heart thanks to Covid plus an addition 20 #s of Seatt weight, I found myself mostly riding a new eBike as well. We decided to eBike convert our CoMotion tandem. It’s equipped with Rohloff hub and Gates belt drives, so front hub. We had it converted at BikeSwift in Seattle. Grin technology with Regeneration Braking. Love it, especially since getting rolling can be much easier. We run about 50 50 with assist off on flats and downs. It takes some practice since the Captain has two more tasks now and braking is a two step process also. It’s a much heavier bike now as well.
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Old 11-06-22, 12:08 PM
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Front hub, eh?
I always thought of this as the least-desirable option, because of added inertia to front steering and likely more complex wiring.
Was I wrong? Could you elaborate on your experience? How is the wheel removal procedure with that hub (in case of flat - my big concern with rear hub)?
Any pictures?
Robert
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Old 11-08-22, 06:18 AM
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Mid drive or hub

I have both mid drive and grin hub tandems…. There are pluses and minus of both… I will be hosting a Zoom with Grin for tandem riders if you want to join in let me know.
I am interested in the regen option….
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Old 11-08-22, 06:48 AM
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Originally Posted by stewclark
I have both mid drive and grin hub tandems…. There are pluses and minus of both… I will be hosting a Zoom with Grin for tandem riders if you want to join in let me know.
I am interested in the regen option….
Sent you a PM. Thanks!
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Old 11-08-22, 07:15 AM
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Originally Posted by rdwalker
Front hub, eh?
I always thought of this as the least-desirable option, because of added inertia to front steering and likely more complex wiring.
Was I wrong? Could you elaborate on your experience? How is the wheel removal procedure with that hub (in case of flat - my big concern with rear hub)?
Any pictures?
Robert
For us, the choice of the front hub was the easiest solution. I converted a late '90's santana tandem which has a non-standard rear drop out spacing and a 6 speed free wheel. Finding a rear motor hub to fit here limits my choices There are also challenges fitting a mid drive, so the front hub was the path of least challenge. I went with the eZee hub, Phaserunner controller, and eZee 36V 24Ah battery with the matching rear rack.

I have not found the extra weight in the front wheels to affect steering at all. It's not a high performance bike to start with and we are not a high performance team, so I did not notice any loss, or negative impact to our normal riding regimen. We are a heavy team and I did not want all the weight on the back wheel (Stoker, Battery, and motor) and I was not comfortable with the strength of the tubing or the water bottle cage bosses holding a heavy battery.

I can't comment too much on wiring as I designed and implemented my own head controller and made all the cables to interface to the ebike hardware. The controller is on the center down tube right at the head tube, the head controller mounts to a garmin out front mount just a few inches away and the motor is right below on the front wheel. I had to custom make the battery cable to reach the battery in the rear. I have both PAS and throttle. Overall all a lot of wires but not unruly. I 3D printed several clips that hold the wiring to the frame tubes so overall routing management was straight forward.

Removing the front wheel is where the big negative is. It requires real crescent wrenches and a socket wrench for the torque arm. Fortunately for us, we transport our tandems in a van so I don't have to remove the front wheel to transport, but I did fashion a simple ramp out of scrap wood to be able roll the bike on and off the vehicle without having to lift the bike.

One advantage of our set up is that by replacing the front motor wheel with a standard wheel and leaving the battery off, it converts back to a regular tandem with just the Phaserunner and some wiring still present. This allows us to have the option of both a regular and an eTandem when we travel somewhere by car and all we have to bring is the extra front wheel.

I can post some pictures if folks are interested.
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Old 01-25-23, 09:50 PM
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We converted a "foot-forward" Sun Brickell7 tandem beachcomber to a mid-drive Bafang motor for hill assist. Later commissioned a custom, coupled steel frame** with many desired changes for handicapped adaptation.
Lessons learned on both builds:
1. Move entire drive train to right, driven by the Bafang.
2. Bafang chain ‘spider’ is threaded for four-hole chainrings only; we finally found a five-ring adapter made by California Cycle I think.
3. Bafang is not centered left to right; chainline is WAY out 1-1/2” to right of normal. This mandates a customized drive train, loads of spacers and new/machined parts, and may hit frames, feet, etc. Changes how you ride- no longer centered left to right in saddle.

4. This precludes any derailleurs. Used Alfine 8-speed which skipped, and Rohloff 11-speed disc hub which is wonderful but costly.

5. #4 and #5 may not clear your frame, period.

6. Bafang has a freewheel; we quickly found a freewheeling chainwheel (Sick Bike Parts is the brand) for the other person so we can pedal and stop independently. This is important on startup and goosing motor on hill or hazard.

7. Second build moved motor and battery to the front under captain for better balance and handling. First build had them in back; front wheel had nearly no weight on it on hills and handled terribly.

8. Enormously heavy bike due to 38 pounds of motor and battery, heavy Rohloff, steel wheels and 18 pound frame: loaded we run about 92# with tools and spares. 400# GWV with riders and medical gear means braking is horrible. We retrofit with 203mm (I think, maybe larger) manual disc brakes but it still takes too long to stop. We retrofit with third caliper rim brake in rear for downhill drag brake- required welding and grinding of our new frame. (It drags but absolutely does not stop us no matter how hard it is squeezed.)

9. 26” steel wheels for strength, 2” Schwalbe Marathon tyres. We bike max 15mph on rail trails and some gravel to explore. Almost never road bike except during Covid. Handles like a tank, cannot U turn in a road have to dismount.

10. Motor: day one I disabled the PAS pedal assist- scary for tandem or handicapped rider. Nudging the pedal resulted in lunging. Reprogrammed the Bafang for throttle-only 100% and have to finger the heads-up display from 0 to 9 before any power to motor, for safety. Also used password protection so someone else cannot start motor once shut off.

11. Motor use: We always pedal and use it for hill assist and soft ground assist. The 1500watt 48-volt motor (52v battery) in low gear can easily pull 400# GVW up a steep hill for ¼ mile without pedaling, without overheating. Typical usage is low throttle 30watt to 325 watts on nonpaved surfaces or windy conditions; 400w to 900w assist on hills. Never had an overheating issue. 20 to 38 mile rail trail trips have only exhausted the battery once, at the very end. Usually draw battery from 58v fully charged down to 50, occasionally 48. Programmed to cut out at 42.



**frame fabrication by Roulez Cycle, Lynn MA.
Eleven builders said it could not be done! Kudos to Jay for a monumental task and loads of custom machining. He is a master of innovation.

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Old 01-12-24, 10:07 AM
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Wayne, your original post was several years ago. Do you still have the same sentiments? We are considering a conversion kit. Our bike mechanic recommended purchasing new, rather than convert. We were talking about a front hub SWYTCH kit. We have a high end co-motion bike. We would like to receive your pics and more info regarding your convert. How often do you ride, how far?
Thanks. I do not see how to personally respond to you? I can provide my email, if you are still there?

Thanks!
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Old 01-12-24, 07:54 PM
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The Swytch kit is probably the easiest conversion option but it depends on how much assistance you want because they are 250 watt motors.

It works for us to balance out headwinds and climbing, but it will only be an overall increase of 2-4 mph.
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Old 01-13-24, 02:20 PM
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Originally Posted by redfoxie123
Wayne, your original post was several years ago. Do you still have the same sentiments? We are considering a conversion kit. Our bike mechanic recommended purchasing new, rather than convert. We were talking about a front hub SWYTCH kit. We have a high end co-motion bike. We would like to receive your pics and more info regarding your convert. How often do you ride, how far?
Thanks. I do not see how to personally respond to you? I can provide my email, if you are still there?

Thanks!
If you are looking at Swytch, I would recommend you also look at the Cytronex C1. (www.cytronex.com) We have one on our CoMo Macchiato, plus I have the C1 on two solo bikes. Very easy to install and remove and very light. 250W motor and 198Wh.
We can get 35 miles in flat FL, plus we have a fitting for a backup battery




on the tandem
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Old 01-14-24, 06:40 PM
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Originally Posted by redfoxie123
Wayne, your original post was several years ago. Do you still have the same sentiments? We are considering a conversion kit. Our bike mechanic recommended purchasing new, rather than convert. We were talking about a front hub SWYTCH kit. We have a high end co-motion bike. We would like to receive your pics and more info regarding your convert. How often do you ride, how far?
Thanks. I do not see how to personally respond to you? I can provide my email, if you are still there?

Thanks!
EMAIL wthais@gmail.com

What is your email?

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