E-MT1000 750W Mid-Drive Project

[flymeaway]

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?

Haven't looked at any electric tandems so it's hard for me to comment. I'd probably still retrofit a good tandem instead of buying. I would use a mid-drive and instead of a rear derailer, I'd use a Rohloff Speedhub.

Court J.

 

[tomjasz]

Haven't looked at any electric tandems so it's hard for me to comment. I'd probably still retrofit a good tandem instead of buying. I would use a mid-drive and instead of a rear derailer, I'd use a Rohloff Speedhub.

Court J.

Fitting a mid drive kit on a tandem is very difficult. It requires some engineering and custom parts. The captain presents a real problem.

We did have a solution but no longer support or produce the fix. https://california-ebike.com/electric-assist-tandems-finally/
"The solution was to install the mid drive in the Captain position and coupling to the Stoker on the right side (contrary to convention) and adding a free wheel at the stoker position. The free wheel is needed for safety and frees up the need for synchronization."

 

[Nxkharra]

This is a work of beauty.
as I mentioned in my other post we just sold our 2015 Cannondale 29er MTB.
I looked for someone to help me find a place to convert to ebike. No one responded so we sold.
this work would be sooooo nice with ours.
great job.
Wish I knew this couple of weeks ago.
here is couple of pics of our Cannondale tandem.

 

[tomjasz]

This is a work of beauty.
as I mentioned in my other post we just sold our 2015 Cannondale 29er MTB.
I looked for someone to help me find a place to convert to ebike. No one responded so we sold.
this work would be sooooo nice with ours.
great job.
Wish I knew this couple of weeks ago.
here is couple of pics of our Cannondale tandem.

Don’t feel to badly. Not all are as easy a conversion as described. I support a BBSxx seller and after vetting several customers we decided a BBS02 conversion wouldn’t be the right move. I hate missing a sale, but kitting isn’t always possible or easy.

 

[Fietsvriend]

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. View attachment 30292View attachment 30293View attachment 30294

Hi SST,Great info!
I have the exact same bike so good to know it can be converted on the stoker end. Did you ever check if the motor can be mounted inside the frame? There is an about 85 degrees free angle there and I would love to retain the original ground clearance.

 

[SST]

Perfect question. When I did the original test fit, I looked at mounting it "inside" the frame first. In my case (2005 tandem) the BBS02 motor housing didn't fit and the gap between the BB spindle and motor was too narrow to get the spindle straight all the way through. You can try when you do your conversion to see if there's any more space, but I could get it all the way through without having to modify the motor housing for me.

This build was for us to get into more regular tandem cycling / exploration and we don't do any single track ☹ - just gravel, grass and unpaved trails so the clearance hasn't been an issue. If you notice in the picture, I had to add a Cirrus Kinekt bodyfloat seatpost for my stoker. I'm thinking about my next build being one with full suspension where I would find a way to tuck the mid-drive inside the frame or go with an integrated frame with the motor built in.

 

[Fietsvriend]

Perfect question. When I did the original test fit, I looked at mounting it "inside" the frame first. In my case (2005 tandem) the BBS02 motor housing didn't fit and the gap between the BB spindle and motor was too narrow to get the spindle straight all the way through. You can try when you do your conversion to see if there's any more space, but I could get it all the way through without having to modify the motor housing for me.

This build was for us to get into more regular tandem cycling / exploration and we don't do any single track ☹ - just gravel, grass and unpaved trails so the clearance hasn't been an issue. If you notice in the picture, I had to add a Cirrus Kinekt bodyfloat seatpost for my stoker. I'm thinking about my next build being one with full suspension where I would find a way to tuck the mid-drive inside the frame or go with an integrated frame with the motor built in.

Ok, thanks. That’s valuable information to me. I will ponder on it some more and may go for the easier rear hub motor wheel.