flymeaway
Well-Known Member
Perhaps but the tires are 1.75" now. The battery and motor added about 40 lbs. I weigh 170, my wife 123. I don't think the total weight is excessive.......but I do wish the battery could have been mounted lower.
E-MT1000 750W Mid-Drive Project
- Thread starter flymeaway
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flymeaway
Well-Known Member
Not to bad on the weight side. The battery and motor add about 40 lbs. My wife weighs 125 and I weigh 170 so the total weight is reasonable. Yeah the lack of suspension makes the ride a little bumpy on occasion but we don't trail ride, we ride on pavement and on gravel roads. The only real downside so far is the battery brings the CG up quite a bit. It's most annoying when we aren't on the bike and I have to walk it, has a tendency to be top heavy. On the plus side, the 750W 48V system makes the tandem easy to ride. Hill climbing is a breeze.....the only change I had to make was to beef up the chain tensioner. The first tensioner pictured above would flex when we were pushing hard and we threw the chain off a couple of time. With the new tensioner the problem was solved. Court J.
Spotty dog
Member
Thats quite a beastie you built how do the brakes cope with the weight and speed, it must get along really well with 2 pairs of legs and a crank drive assisting.
Given your type of riding some big apple or fat frank tyres could work well if you have the clearence to fit them.
Given your type of riding some big apple or fat frank tyres could work well if you have the clearence to fit them.
flymeaway
Well-Known Member
My wife and I combined weigh about 290 lbs. so it's really not much different then an average weight pair on the bike. The bike does really well on grades taking a lot of grunting out of the ride. I limit the speed assist on the controller to 20MPH; no need to go flying along. So far the brakes haven't been a problem. If you like riding a tandem adding the Bafang kit is worth considering, makes longer distance touring a pleasure.
Spotty dog
Member
My girlfriend is up for a tandem am giving it serious consideration 
Greg H.
Member
flymeaway
Well-Known Member
Laughing
It really goes quite nicely with the BBS02 48V 750W. My only regret is placing the battery over the rear wheel. If I ever make another I'd locate the battery somewhere else. I'd also entertain thoughts (if I was 30-40 years younger) of doing a tandem for cross country. Buy or build a trailer to tow and put the battery there. You could easily end up with a very capable 150+ mile E-Tandem. Heck...I might just do it for the challenge!Court J.
From what you know here in 2019, would you choose again to retrofit your cannondale tandem with the latest Bafang kit, or spend significantly more to purchase one of the very few factory built electric tandems? I have a 1980 Cannondale street tandem (aluminum frame, built in America, Phil Wood hubs, other great components) with the same general frame tubes as yours. Tandem riding is a favorite past time for my wife and I, and we love our bike. I want a solution that is neat-and-tidy and provides good range, comfortable 14 - 20 mph performance, reliability, and maintability over time.
Some people say a motor adds too much torque to the drive train never engineered for that purpose. I would also have to deal with the stoker right side chain rings like you did. Others say that hub motors are on the way out, or add too much pedal resistance if the battery runs completely out. Still others say to take the financial plunge and just buy a true ebike rather than retrofit so you don't have to deal with continual tweaking, fixing, and parts obsolescence.
Your thoughts on the overall strategy would be greatly appreciated. I realize I'll still have to take measurements to finish assessing feasibility.
Thanks in advance.
CaptnKirk (Where is Scotty when we need him??)
Thanks for your quick response, and I agree. Next I'll research and select a good hub drive make and model, and choose front or rear drive. Are there some leading hub drive contenders in your opinion that would benefit a tandem that I should start with?
If front drive handles and corners well on a tandem, the easier maintenance, installation, and better weight distribution would be attractive. Is there a reason to favor front of rear drive? I will know by Thursday if I have a steel fork.
Thanks again for your input.
CaptnKirk
I did a similar build 4 months ago with a 2005 Cannondale Mountain Tandem debating the same issues. I've worked with hub motors on my single rider ebikes but didn't care for the shift in the center of gravity and was concerned a front hub motor would change the handling of the tandem too much. If you end up going down that path, maybe consider a rear hub implementation? For us, it ended up being a better tandem riding experience with a mid-drive, but the trade-off (and you'll need to determine what you want to favor) is a more complex build. Hub motor's definitely going to be an easier installation. Here's a few pics on how mine ended up. I changed a few things on the drivetrain to optimize our tandem for hillclimbing performance and moderate assist. I put the BBS02 on the stoker position. You lose the front derailleur with a mid-drive build and you need to be comfortable with working with the drivetrain.
Very interesting. Looks like an elegant build. Are you happy with the bike's ride and performance now? Does the Bafang pedal assist feel responsive, and does the bike shift well?
I have no problem doing the mechanical work as long as I don't have to machine new parts. Did the Bafang motor fit easily in the bottom bracket?
My 1980 Cannondale tandem has only 6 gears on the rear cassette. Do you think this will be a problem for BBS02 assist? Finally, where did you purchase your kit?
Thanks for your input!
I have no problem doing the mechanical work as long as I don't have to machine new parts. Did the Bafang motor fit easily in the bottom bracket?
My 1980 Cannondale tandem has only 6 gears on the rear cassette. Do you think this will be a problem for BBS02 assist? Finally, where did you purchase your kit?
Thanks for your input!
tomjasz
Well-Known Member
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- Minnesnowta
MAC motor and EM3ev battery and controller. Hands down. eBikes.ca CA-3 display. If you can sort connectors (every DIY needs to or hire a good LBS with soldering skills) I’d go MAC and FOC controller from Grin and their CA-3. An all Grin EZee build would be sweet too. But the eZee is not as powerful as a MAC. Either would be good choices. Short of a 72v battery and a direct drive monster for the speed freaks...
tomjasz
Well-Known Member
- Region
- USA
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- Minnesnowta
You’re welcome, but I hate not peddling what I peddle, and pedal! VBGThanks
The tandem performance exceeded my expectations. Handling and balance with both my wife and I feel very natural to ride and similar to pre-conversion. I got my mid-drive setup from LunaCycle, but there's a lot of good vendors out there.
I have a gear sensor to the setup - so the motor cuts off during shifts. There's a lot of torque on a tandem so probably a good option to have to protect the drivetrain. On the 2005 Cannondale Mountain Tandem, there was a standoff on the bottom of the stoker position that was used to anchor the front derailleur. To make the fit easier, I ground down the standoff (it was about 1/4"). That was it. The BB, installation for the mid-drive was the same as for a single bike. I did change the chainrings for the timing chain and the front chainring to 34T. The total weight of riders / bike / setup is around 300 lbs. We can do either full assist or partial assist on over 20 degree climbs without straining the drivetrain. One of the deciding factors in going this way for me was the control over how power was applied to bias for torque (for hill-climbing) or speed with this type of approach. There's some good online bike calculators like the one I used at http://www.kreuzotter.de/english/espeed.htm to help you plan for your setup. It would probably be worth a few mins to plan your setup for your 6 gear ratios.
Thomas - no worries. I have experience with several generations of eZee hub drive setups and even some Panasonic ones that Giant used on their ebike platforms. For me, the considerations were: small front hub - least impact on balance / handling but less power, larger front hub - I didn't like the weight and control / turning radius + the larger hub motors created a centripetal / gyroscopic force at speed which made the bike both more stable and less easy to handle. I was also concerned in a tandem application the additional forces on the front forks and stem. there's already a lot of additional strain on the front forks with braking, etc. Hence my suggestion for a rear hub setup. For a single bike, none of these are big issues, but they get magnified for my tandem application. The other issue was that I just wanted a lot of low end torque. I'm not as fit as I used to be and my wife and I are terrible at coordinating our riding for climbs.
I have a gear sensor to the setup - so the motor cuts off during shifts. There's a lot of torque on a tandem so probably a good option to have to protect the drivetrain. On the 2005 Cannondale Mountain Tandem, there was a standoff on the bottom of the stoker position that was used to anchor the front derailleur. To make the fit easier, I ground down the standoff (it was about 1/4"). That was it. The BB, installation for the mid-drive was the same as for a single bike. I did change the chainrings for the timing chain and the front chainring to 34T. The total weight of riders / bike / setup is around 300 lbs. We can do either full assist or partial assist on over 20 degree climbs without straining the drivetrain. One of the deciding factors in going this way for me was the control over how power was applied to bias for torque (for hill-climbing) or speed with this type of approach. There's some good online bike calculators like the one I used at http://www.kreuzotter.de/english/espeed.htm to help you plan for your setup. It would probably be worth a few mins to plan your setup for your 6 gear ratios.
Thomas - no worries. I have experience with several generations of eZee hub drive setups and even some Panasonic ones that Giant used on their ebike platforms. For me, the considerations were: small front hub - least impact on balance / handling but less power, larger front hub - I didn't like the weight and control / turning radius + the larger hub motors created a centripetal / gyroscopic force at speed which made the bike both more stable and less easy to handle. I was also concerned in a tandem application the additional forces on the front forks and stem. there's already a lot of additional strain on the front forks with braking, etc. Hence my suggestion for a rear hub setup. For a single bike, none of these are big issues, but they get magnified for my tandem application. The other issue was that I just wanted a lot of low end torque. I'm not as fit as I used to be and my wife and I are terrible at coordinating our riding for climbs.
SST and Thomas,
I really appreciate your time and effort to reply. It's given me some very helpful perspective. Both the mid drive BBS02 and rear gear hub motors look very promising at this point. I like the higher torque and efficiency that appears to come from the BBS02, but I would have to re-route my rear shift cable that currently runs under the bottom horizontal tube, and make minor mods that SST mentioned. A rear hub motor would be easier to install, and may not have quite the steep hill climbing abilities of the mid drive, but we mostly ride paved rail trails at 14 - 18 mph for 30 miles (hopefully growing to 50 - 70 miles with electric assist) and maybe the hub drive is all we need? Our complete weight on the converted tandem would be approx. 420 lbs. I'm deciding whether this is too much for a geared hub, and whether a mid drive installation would be too onerous.
Thanks again!
CaptnKirk
I really appreciate your time and effort to reply. It's given me some very helpful perspective. Both the mid drive BBS02 and rear gear hub motors look very promising at this point. I like the higher torque and efficiency that appears to come from the BBS02, but I would have to re-route my rear shift cable that currently runs under the bottom horizontal tube, and make minor mods that SST mentioned. A rear hub motor would be easier to install, and may not have quite the steep hill climbing abilities of the mid drive, but we mostly ride paved rail trails at 14 - 18 mph for 30 miles (hopefully growing to 50 - 70 miles with electric assist) and maybe the hub drive is all we need? Our complete weight on the converted tandem would be approx. 420 lbs. I'm deciding whether this is too much for a geared hub, and whether a mid drive installation would be too onerous.
Thanks again!
CaptnKirk
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