preventec47

I was looking at some cargo bike examples and I felt like I could design a bed carrier that would mount into the stoker seatpost after removing the seat and
on the sides connect somehow to the chain stays. BAsically two large compartments on either side of the bike that could be added or removed very easily
and swapped with the normal stoker seat.
Getting some ideas from these photos.....

sdodd

Are you looking to convert the tandem from a 2 person bike to a 1 person bike + cargo or are you trying to make a 2 person bike + cargo?
The former seems reasonable.
Extending the wheelbase on a tandem to add cargo capacity would need to be carefully thought out. There is significantly more stress on a bike carrying two people compared to one person.

preventec47

No I am not thinking of expanding the wheelbase of a tandem, I am just recognizing that the second seat is already a cargo position of sorts in that the cargo is a passenger. If I can change the seat into a couple of buckets on each side or a platform like a truck bed then I can convert the tandem from a cargo bike back to a 2 seater by removing the carry bed by pulling it out of the seat post hole and reinserting the stoker seat.

sdodd

Yeah - If you don't have a need for 2 people AND cargo then your suggested idea of using the stoker position as a cargo position would give you the safest and easiest conversion. You could start with the seatpost - build something that mounts on a rear rack mount or attaches to the rear drop outs - then extend to a reasonable point in the front. Perhaps some type of quick release clamp to the stoker handlebars? There isn't any other 'standard' robust mount between the stoker and the captain.

CargoDane

If you don't need to ever have a stoker back there (so you can remove the pedals), you can have the cargo lower - regardless of them being buckets or panniers. But if that is what you want, let me recommend you buy a good cargo bike instead: Buy a two wheeled one, and with the cargo platform in front of you (makes it easier to steer than you sitting at the front of a tandem with a load at the back).

Edit:
If you need it to sometimes carry a stoker instead of cargo, you have to take the pedals into account, meaning the weight will suddenly be pretty far back and/or up high.

bazil4696

preventec47

I plan to continue to ride with stokers most of the time but if I had an occasion to need to haul cargo then being able to "convert" my bike would be pretty cool.
Getting two for one so to speak in functionality.

tgot 

Depending on how much cargo, something like this:

Rack on a seatpost.

Might be enough. Unfortunately, I got it as part of the fairly expensive kid seat option here:https://www.amazon.com/gp/aw/d/B0027P9CX2#Ask

But I've also put it in the rear position of my tandem, and hooked panniers on it.


Depending on the tandem that surface and pannier hang might be just as low as a regular rear rack.

I haven't done it, but I could put three pair of panniers on my tandem and have three racktop surfaces to anchor to also.

Daveysprockets1

Check out "Ultimate cargo bike converted tandem" on youtube...amazing !!

jccaclimber

I was going to say to just find/make a Xtracycle type device for a single, but then you mentioned wanting a stoker occasionally.
Is this as simple as removing the stoker pedals (assuming not a DaVinci, in which case you could leave them on) and putting mount bars for paniers along the stoker's top tube and at the sides of their seat?

Daveysprockets1

check out on youtube "Ultimate Cargo Bike.? Converted tandem"