Dual Cruzbike Conversion on a Tandem?

[Charles.Plager]

Hi,

Here's my wacky idea of the day:

Two Cruzbike conversion kits (or at least, 1 full kit, one additional seat)

And something like this:

My thought is that one does the full conversion on the front, install the seat on the back and have the stoker pedal what would be the captain's pedals.

With this model, you'd have to worry somewhat about the stokers feet hitting the captain's seat, but this has got to be one of the cheapest routes to a recumbent tandem (not to mention that it would actually be a true IPS (independent pedaling system) as each occupant gets their own gears).

Thoughts? (Doug, I won't be satisfied until you chime in...)

Cheers,
Charles

p.s. Here's another option: (but I'm worried the captain's seat would be too high):

 

[Ian Smith]

Movement

Charles,

I would suspect that you'd have to be carful with the balancing. The person on the back would act a bit like having a child on the back in that the captain will always be trying to fight the movement of the stoker. Any small move of the stoker can upset the balance of the bike. This is compounded if the captain and the stoker are at different cadences and the fact that balancing on a recumbent tandem is not as easy as a 'normal' tandem. That said, I think that it can be done with practice and communication.

I know that having a child on the back can be 'entertaining' and frustrating at the same time, especially when they decide to lean out and look down at the wheel.

A leaning recumbent tandem trike with centering springs would be a whole lot easier. Sort of like riding with adaptive training wheels.

 

[Charles.Plager]

Hi Ian,
I ride my Cruzbikes

Hi Ian,

I ride my Cruzbikes with trail-a-bikes, so I'm used to the different cadences. Of course my wife weights a bit more than my 6 year old daughter (and its easier with my daughter who knows how to ride than it is with my 4 year old son who's still figuring it out for the reasons you pointed out). I do agree that it would be not completely trivial at first, but as you point out, I'm fairly confident it could be done well and safely with practice and communication.

I agree that a leaning tandem trike is something of the holy grail here (and I'm hoping John is done messin' 'round with the new bikes so he can get back to working on a Cruzbike leaning trike), but I'm not going to be able to put one together for anywhere near the price point of what I'm suggesting.

Cheers,
Charles

 

[Doug Burton]

Given a lot of thought to this...

Charles,

The principal issue I've found with converting a standard tandem is the distance between the rear wheel and the front bottom bracket is generally pretty short - 22 inches or so in the frames I've measured. This can be alleviated somewhat by raising the height of the stoker seat, but then knee interference with the front seatback comes into play.

I am interested in building a compact tandem using a simple straight frame, 451mm wheels ala Quest 20 with dualdrives, with the frame overhanging the rear wheel. I have purchased a long piece of 80/20 aluminum extrusion to build a frame jig, but real life prevents progress these days.

I also tried very hard to get one of these imported, but the English retailers weren't interested, regardless of price and shipping cost.

 

[Charles.Plager]

O.k.  Here's what I did.  I

O.k. Here's what I did. I took the picture of the tandem from above and a Rans Seavo. The Seavo has a wheel base of 79 inches; the Amazon tandem 71; The orange lines, which go from axle to axle are the appropriate lengths and then I scaled the image to fit.

The bikes are lined up via the front crank via the green line. The red seats are aligned vertically and are leveled by eye to about the same place.

What I see from this is that:

* The amazon tandem picture isn't square.


* Doug is (of course) right that the rear wheel is closer to the front crank than the recumbent bike


* The rear seat wouldn't have quite the same room on this, but my wife is, err..., vertically challenged so that won't be an issue. It does look like I can get the passenger seat close enough to the crank and not have too much interference from the front seat.

* I'd probably want the front seat a little closer relatively speaking than the Rans (both for rear stoker room and reaching the pedals).

* The passengers would be a bit further forward relatively speaking on the Cruzbike tandem, but not so much that I see a problem.

This looks (very preliminarlily) mostly promising...

Doug, others, more thoughts?